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1

Pima Indians: Pathfinders for Health.  

National Technical Information Service (NTIS)

Contents: The Pima Indians: Pathfinders for Health; The Pima Indians and Genetic Research; Breaking the Vicious Cycle; A Pima Mother and Her Daughters; Advanced Technology Used to Measure Energy Expenditure; Kidney Disease of Diabetes in the Pima Indians;...

J. Demouy J. Chamberlain M. Harris L. H. Marchand

1995-01-01

2

PATHFINDER  

NSDL National Science Digital Library

PATHFINDER is a new Web Site created by the Time Warner Group of companies. In Pathfinder you will find samples of Time Warner's products including: Time, People, Money, Entertainment Weekly, Fortune, and Real Simple.

3

Oral health related behaviors among adult Tanzanians: a national pathfinder survey  

Microsoft Academic Search

BACKGROUND: The oral health education programs which have been organised and delivered in Tanzania were not based on a thorough understanding of behaviours which influence oral health. Therefore, evaluation of these programs became difficult. This study aimed at investigating the oral health related behaviours and their determinants among Tanzanian adults. METHODS: A national pathfinder cross sectional survey was conducted in

Joyce R Masalu; Emil N Kikwilu; Febronia K Kahabuka; Ahadieli R Senkoro; Irene A Kida

2009-01-01

4

Shifting the paradigm of coral-reefhealth’ assessment  

Microsoft Academic Search

Coral reefs are in crisis. Globally, our reefs are degrading at an accelerating rate and present methodologies for coral-reefhealth’ assessment, although providing important information in describing these global declines, have been unable to halt these declines. These assessments are usually employed with no clear purpose and using uncorrelated methods resulting in a failure to prevent or mitigate coral reef

Craig A. Downs; Cheryl M. Woodley; Robert H. Richmond; Lynda L. Lanning; Richard Owen

2005-01-01

5

Research Spotlight: New method to assess coral reef health  

NASA Astrophysics Data System (ADS)

Coral reefs around the world are becoming stressed due to rising temperatures, ocean acidification, overfishing, and other factors. Measuring community level rates of photosynthesis, respiration, and biogenic calcification is essential to assessing the health of coral reef ecosystems because the balance between these processes determines the potential for reef growth and the export of carbon. Measurements of biological productivity have typically been made by tracing changes in dissolved oxygen in seawater as it passes over a reef. However, this is a labor-intensive and difficult method, requiring repeated measurements. (Geophysical Research Letters, doi:10.1029/2010GL046179, 2011)

Tretkoff, Ernie

2011-03-01

6

Emotional Pathfinding  

Microsoft Academic Search

\\u000a This paper presents a study of the influence of emotions on the behaviour of an intelligent pathfinding agent. A model of\\u000a pathfinding is proposed that takes into account the emotional state of the agent. Results show that blindly following the\\u000a most urgent emotion can lead to degenerate behaviour, and that cross-exclusion can be used to effectively moderate emotional\\u000a influences. Applications

Toby Donaldson; Andrew Park; I-ling Lin

2004-01-01

7

Coral reef health and effects of socio-economic factors in Fiji and Cook Islands  

Microsoft Academic Search

This research focuses on coral reef health in the South Pacific region, an area of high global coral diversity. Coral reef health surrounding four island case studies in the Cook Islands and Fiji have been assessed in areas that have not been previously surveyed. This study compares four islands with barrier and fringing reefs that have different levels of economic

Tegan Churcher Hoffmann

2002-01-01

8

TEMPORAL TRENDS IN THE HEALTH OF SOUTH FLORIDA CORAL REEFS  

EPA Science Inventory

Barron, M.G., D.L. Santavy, L. MacLaughlin, E. Mueller, E. Peters, B. Quarles and J. Campbell. In press. Temporal Trends in the Health of South Florida Coral Reefs (Abstract). To be presented at the SETAC Fourth World Congress, 14-18 November 2004, Portland, OR. 1 p. (ERL,GB R100...

9

Oral health related behaviors among adult Tanzanians: a national pathfinder survey  

PubMed Central

Background The oral health education programs which have been organised and delivered in Tanzania were not based on a thorough understanding of behaviours which influence oral health. Therefore, evaluation of these programs became difficult. This study aimed at investigating the oral health related behaviours and their determinants among Tanzanian adults. Methods A national pathfinder cross sectional survey was conducted in 2006 involving 1759 respondents from the six geographic zones of mainland Tanzania. Frequency distributions, Chi square and multiple logistic regression analyses were performed using SPSS version 13.0. Results The rates of abstinence from alcohol for the past 30 days and life time smoking were 61.6% and 16.7% respectively, with males being more likely to smoke (OR 9.2, CI 6.3 -12.9, p < 0.001) and drink alcohol (OR 1.5, CI 1.2 -1.8, p < 0.001). Multiple regression analysis revealed that; having dental pain (OR 0.7, CI 0.5-0.8; p < 0.001) and being minimally educated (OR 0.48, CI 0.4-0.6; p < 0.001) reduced the likelihood of having a high sugar score. Whereas being male (OR 1.5, CI 1.2- 1.8; p < 0.001), urban (OR 1.9, CI 1.5 -2.3; p < 0.001), and young (OR 1.5, CI 1.2 -1.8; p < 0.001) increased the likelihood of having a high sugar score. Urban residents were less likely to take alcohol (OR 0.7, CI 0.6-0.9; p < 0.01), or smoke cigarette (OR = 0.7, CI = 0.6-0.9); less likely to be those who do not use fruits (OR 0.3, CI 0.2-0.4; p < 0.001); dental clinic (OR 0.5, CI 0.4-0.7; p < 0.001); factory made tooth brushes (OR 0.1, CI 0.08-0.17; p < 0.001) and toothpaste (OR 0.1, CI 0.1-0.2; p < 0.001) than their rural counterparts. More rural (13.2%) than urban (4.6%) residents used charcoal. Conclusion The findings of this study demonstrated social demographic disparities in relation to oral health related behaviors, while dental pain was associated with low consumption of sugar and high likelihood to take alcohol.

Masalu, Joyce R; Kikwilu, Emil N; Kahabuka, Febronia K; Senkoro, Ahadieli R; Kida, Irene A

2009-01-01

10

LISA Pathfinder  

Microsoft Academic Search

LISA Pathfinder, formerly known as SMART-2, is the second of the European Space Agency's Small Missions for Advanced Research and Technology. The mission will pave the way for the joint ESA\\/NASA Laser Interferometer Space Antenna (LISA), by testing the core assumption of gravitational wave detection - and to a larger extent, General Relativity - that free particles follow geodesics. In

Robin T. Stebbins; P. W. McNamara

2009-01-01

11

DECIGO pathfinder  

Microsoft Academic Search

DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory), which is a future space gravitational wave antenna. DECIGO is expected to provide fruitful insights into the universe, particularly about dark energy, the formation mechanism of supermassive black holes and the inflation of the universe. Since DECIGO will be an extremely challenging mission, which will

Masaki Ando; Seiji Kawamura; Shuichi Sato; Takashi Nakamura; Kimio Tsubono; Akito Araya; Ikkoh Funaki; Kunihito Ioka; Nobuyuki Kanda; Shigenori Moriwaki; Mitsuru Musha; Kazuhiro Nakazawa; Kenji Numata; Shin-ichiro Sakai; Naoki Seto; Takeshi Takashima; Takahiro Tanaka; Kazuhiro Agatsuma; Koh-suke Aoyanagi; Koji Arai; Hideki Asada; Yoichi Aso; Takeshi Chiba; Toshikazu Ebisuzaki; Yumiko Ejiri; Motohiro Enoki; Yoshiharu Eriguchi; Masa-Katsu Fujimoto; Ryuichi Fujita; Mitsuhiro Fukushima; Toshifumi Futamase; Katsuhiko Ganzu; Tomohiro Harada; Tatsuaki Hashimoto; Kazuhiro Hayama; Wataru Hikida; Yoshiaki Himemoto; Hisashi Hirabayashi; Takashi Hiramatsu; Feng-Lei Hong; Hideyuki Horisawa; Mizuhiko Hosokawa; Kiyotomo Ichiki; Takeshi Ikegami; Kaiki T. Inoue; Koji Ishidoshiro; Hideki Ishihara; Takehiko Ishikawa; Hideharu Ishizaki; Hiroyuki Ito; Yousuke Itoh; Nobuki Kawashima; Fumiko Kawazoe; Naoko Kishimoto; Kenta Kiuchi; Shiho Kobayashi; Kazunori Kohri; Hiroyuki Koizumi; Yasufumi Kojima; Keiko Kokeyama; Kei Kotake; Yoshihide Kozai; Hideaki Kudoh; Hiroo Kunimori; Hitoshi Kuninaka; Kazuaki Kuroda; Kei-ichi Maeda; Hideo Matsuhara; Yasushi Mino; Osamu Miyakawa; Shinji Miyoki; Mutsuko Y. Morimoto; Tomoko Morioka; Toshiyuki Morisawa; Shinji Mukohyama; Shigeo Nagano; Isao Naito; Kouji Nakamura; Hiroyuki Nakano; Kenichi Nakao; Shinichi Nakasuka; Yoshinori Nakayama; Erina Nishida; Kazutaka Nishiyama; Atsushi Nishizawa; Yoshito Niwa; Taiga Noumi; Yoshiyuki Obuchi; Masatake Ohashi; Naoko Ohishi; Masashi Ohkawa; Norio Okada; Kouji Onozato; Kenichi Oohara; Norichika Sago; Motoyuki Saijo; Masaaki Sakagami; Shihori Sakata; Misao Sasaki; Takashi Sato; Masaru Shibata; Hisaaki Shinkai; Kentaro Somiya; Hajime Sotani; Naoshi Sugiyama; Yudai Suwa; Rieko Suzuki; Hideyuki Tagoshi; Fuminobu Takahashi; Kakeru Takahashi; Keitaro Takahashi; Ryutaro Takahashi; Ryuichi Takahashi; Tadayuki Takahashi; Hirotaka Takahashi; Takamori Akiteru; Tadashi Takano; Keisuke Taniguchi; Atsushi Taruya; Hiroyuki Tashiro; Yasuo Torii; Morio Toyoshima; Shinji Tsujikawa; Yoshiki Tsunesada; Akitoshi Ueda; Ken-ichi Ueda; Masayoshi Utashima; Yaka Wakabayashi; Hiroshi Yamakawa; Kazuhiro Yamamoto; Toshitaka Yamazaki; Jun'ichi Yokoyama; Chul-Moon Yoo; Shijun Yoshida; Taizoh Yoshino

2009-01-01

12

DECIGO pathfinder  

Microsoft Academic Search

DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected to provide us fruitful insights into the universe, in particular about dark energy, a formation mechanism of supermassive black holes, and the inflation of the universe. Since DECIGO will be an extremely large mission

M. Ando; S. Kawamura; T. Nakamura; K. Tsubono; T. Tanaka; I. Funaki; N. Seto; K. Numata; S. Sato; K. Ioka; N. Kanda; T. Takashima; K. Agatsuma; T. Akutsu; K.-s. Aoyanagi; K. Arai; Y. Arase; A. Araya; H. Asada; Y. Aso; T. Chiba; T. Ebisuzaki; M. Enoki; Y. Eriguchi; M.-K. Fujimoto; R. Fujita; M. Fukushima; T. Futamase; K. Ganzu; T. Harada; T. Hashimoto; K. Hayama; W. Hikida; Y. Himemoto; H. Hirabayashi; T. Hiramatsu; F.-L. Hong; H. Horisawa; M. Hosokawa; K. Ichiki; T. Ikegami; K. T. Inoue; K. Ishidoshiro; H. Ishihara; T. Ishikawa; H. Ishizaki; H. Ito; Y. Itoh; S. Kamagasako; N. Kawashima; F. Kawazoe; H. Kirihara; N. Kishimoto; K. Kiuchi; S. Kobayashi; K. Kohri; H. Koizumi; Y. Koima; K. Kokeyama; W-Kokuyama; K. Kotake; Y. Kozai; H. Kudoh; H. Kunimori; H. Kuninaka; K. Kuroda; K.-i. Maeda; H. Matsuhara; Y. Mino; O. Miyakawa; S. Miyoki; M. Y. Morimoto; T. Morioka; T. Morisawa; S. Moriwaki; S. Mukohyama; M. Musha; S. Nagano; I. Naito; N. Nakagawa; K. Nakamura; H. Nakano; K. Nakao; S. Nakasuka; Y. Nakayama; E. Nishida; K. Nishiyama; A. Nishizawa; Y. Niwa; M. Ohashi; N. Ohishi; M. Ohkawa; A. Okutomi; K. Onozato; K. Oohara; N. Sago; M. Saijo; M. Sakagami; S.-i. Sakai; S. Sakata; M. Sasaki; T. Sato; M. Shibata; H. Shinkai; K. Somiya; H. Sotani; N. Sugiyama; Y. Suwa; H. Tagoshi; K. Takahashi; T. Takahashi; H. Takahashi; R. Takahashi; A. Takamori; T. Takano; K. Taniguchi; A. Taruya; H. Tashiro; M. Tokuda; M. Tokunari; M. Toyoshima; S. Tsujikawa; Y. Tsunesada; K.-i. Ueda; M. Utashima; H. Yamakawa; K. Yamamoto; T. Yamazaki; J. Yokoyama; C.-M. Yoo; S. Yoshida; T. Yoshino

2008-01-01

13

Mars Pathfinder  

NSDL National Science Digital Library

This extensive site from NASA's Jet Propulsion Laboratory is divided into two parts. The first features information available at the time of Pathfinder's 1997 landing on Mars while the second part focuses on information available at the end of the mission. Each part presents archived news and science articles, data and general mission information as well as many images. The site is searchable and includes links to related information.

Laboratory, Nasa J.

14

LISA Pathfinder  

NASA Astrophysics Data System (ADS)

LISA Pathfinder, formerly known as SMART-2, is the second of the European Space Agency's Small Missions for Advanced Research and Technology. The mission will pave the way for the joint ESA/NASA Laser Interferometer Space Antenna (LISA), by testing the core assumption of gravitational wave detection - and to a larger extent, General Relativity - that free particles follow geodesics. In order to meet the goals of the mission, and to prepare the way for LISA, several new technologies must be demonstrated in a space environment. These include: inertial sensors, high-precision laser metrology, drag-free control and micro-Newton proportional thrusters. LISA Pathfinder will carry two payloads: the LISA Technology Package (LTP), provided by European Member States and ESA, and the Disturbance Reduction System (DRS) provided by NASA. The DRS has passed its pre-ship acceptance review and has been delivered to ESA, while the LTP has passed its Critical Design Review, with flight hardware currently being manufactured and tested. The spacecraft development is also proceeding well; the flight structures of both the science module and propulsion module are undergoing environmental testing, while subsystem flight hardware is being delivered to the spacecraft testbeds. LISA Pathfinder will be launched on a dedicated launch vehicle in late 2010. After 15 apogee raising manoeuvres, the sciencecraft will enter its final orbit around the first Sun-Earth Lagrange point. First science results are expected approximately three months after launch. Here we will give an overview of the mission including the technologies being demonstrated. We will also report on the status of the flight hardware testing, and on the status of the ground system.

Stebbins, Robin T.; McNamara, P. W.

2009-01-01

15

Decigo Pathfinder  

NASA Astrophysics Data System (ADS)

DECIGO Pathfinder (DPF) is a small ( 350 kg) satellite orbiting the Earth. DPF was originally proposed as the first milestone mission for a future space gravitational-wave (GW) antenna, DECi-hertz Interferometer Gravitational wave Observatory (DECIGO). In addition to the purpose of space demonstrations for DECIGO, DPF has scientific objectives: observation of GWs from black-hole mergers and monitor of Earth's gravity, as well as establishment of space technologies for high-precision measurements. In this paper, we review the conceptual design, scientific outcomes and the current status of DPF.

Ando, Masaki; The Decigo Working Group,

2013-01-01

16

Turning science into health solutions: KEMRI’s challenges as Kenya’s health product pathfinder  

Microsoft Academic Search

BACKGROUND: A traditional pathway for developing new health products begins with public research institutes generating new knowledge, and ends with the private sector translating this knowledge into new ventures. But while public research institutes are key drivers of basic research in sub-Saharan Africa, the private sector is inadequately prepared to commercialize ideas that emerge from these institutes, resulting in these

Ken Simiyu; Hassan Masum; Justin Chakma; Peter A Singer

2010-01-01

17

Turning science into health solutions: KEMRI's challenges as Kenya's health product pathfinder  

PubMed Central

Background A traditional pathway for developing new health products begins with public research institutes generating new knowledge, and ends with the private sector translating this knowledge into new ventures. But while public research institutes are key drivers of basic research in sub-Saharan Africa, the private sector is inadequately prepared to commercialize ideas that emerge from these institutes, resulting in these institutes taking on the role of product development themselves to alleviate the local disease burden. In this article, the case study method is used to analyze the experience of one such public research institute: the Kenya Medical Research Institute (KEMRI). Discussion Our analysis indicates that KEMRI’s product development efforts began modestly, and a manufacturing facility was constructed with a strategy for the facility’s product output which was not very successful. The intended products, HIV and Hepatitis B diagnostic kits, had a short product life cycle, and an abrupt change in regulatory requirements left KEMRI with an inactive facility. These problems were the result of poor innovation management capacity, variability in domestic markets, lack of capital to scale up technologies, and an institutional culture that lacked innovation as a priority. However, KEMRI appears to have adapted by diversifying its product line to mitigate risk and ensure continued use of its manufacturing facility. It adopted an open innovation business model which linked it with investors, research partnerships, licensing opportunities, and revenue from contract manufacturing. Other activities that KEMRI has put in place over several years to enhance product development include the establishment of a marketing division, development of an institutional IP policy, and training of its scientists on innovation management. Summary KEMRI faced many challenges in its attempt at health product development, including shifting markets, lack of infrastructure, inadequate financing, and weak human capital with respect to innovation. However, it overcame them through diversification, partnerships and changes in culture. The findings could have implications for other research institutes in Sub-Saharan Africa seeking to develop health products. Such institutes must analyze potential demand and uptake, yet be prepared to face the unexpected and develop appropriate risk-mitigating strategies.

2010-01-01

18

Reef Check  

NSDL National Science Digital Library

Reef Check, headquartered at the Institute of the Environment at the University of California Los Angeles, is a "volunteer, community-based monitoring protocol designed to measure the health of coral reefs on a global scale." With scientific reef surveys conducted in over 60 countries and territories, Reef Check has been able to track global trends in reef health to better inform possible conservation strategies. Visitors to the Reef Check Web site can read result summaries for the 1997-2001 monitoring period, and check out the organization's current and archived newsletters. Other resources include information on survey methods, Reef Check publications, a species identification guide, and other resources geared mainly toward Reef Check volunteers.

19

The health and future of coral reef systems  

Microsoft Academic Search

Coral reefs are among the most productive and diverse ecosystems on earth and provide a multitude of valuable ecosystem services. Moreover, the resources derived from coral reefs are essential to the food security of millions of people living within tropical coastal communities. Unfortunately, burgeoning human populations in coastal regions are placing an unsustainable burden on these resources such that degradation

David W Souter; Olof Lindén

2000-01-01

20

Coastal nutrification and coral health at Porto Seguro reefs, Brazil  

NASA Astrophysics Data System (ADS)

Human activities have substantially increased the natural flux of nutrients to coastal systems worldwide. In Brazilian reefs, all major stresses (sedimentation, overfishing, tourism-related activities and nutrification) are human induced. To assess nutrification levels in Brazilian coastal reefs, measurements of the distribution patterns of nutrients and chlorophyll concentrations were conducted in three nearshore and offshore reefs with distinct nutrient inputs along the south coast of Bahia State. Seawater and porewater samples were analysed for soluble reactive phosphorus, total oxidised nitrogen and reactive silica. Benthic surveys were performed at all sites to investigate the relationships between benthic community composition and nutrient and chlorophyll concentrations. Sampling was undertaken in dry and rainy seasons. Results of both seawater and porewater nutrient measurements revealed the occurrence of consistent spatial and temporal patterns. An inshore-offshore gradient reflects the occurrence of land-based point sources, with significant amount of nutrients being delivered by human activities on the coast (untreated sewage and groundwater seepage). Another spatial gradient is related to distance from a localized source of pollution (an urban settlement without sewerage treatment) with two nearshore reefs presenting distinct nutrient and chlorophyll concentrations. Seasonal variations suggest that submarine groundwater discharge (SGD) is the primary source of nutrients for the coastal reefs during rainy season. The data also suggests that the SGD effect is not restricted to nearshore reefs, and may be an important factor controlling the differences between landward and seaward sides on the offshore reef. Benthic community assessment revealed that turf alga is the dominant group in all studied reefs and that zoanthids are the organisms most adapted to take advantage of nutrient increase in coastal areas. At nearshore reefs, there was a negative correlation between zoanthids and algal abundance and a positive correlation with the amount of available space for settlement. On the offshore reef, correlation of algal cover with both zoanthids and available space were negative, suggesting that hard substrate may be the primary limiting factor for algal settlement and growth in the nearshore reefs. Highly variable physical disturbances (like wave energy and low tide exposure) between landward and seaward reef sides appear to be the factors controlling algal distribution in the offshore reef. Highly spatial variability in coral cover ultimately reflects the patchy distribution of stony corals over the reefs.

Costa, O.; Attrill, M.; Nimmo, M.

2003-04-01

21

Pathfinder: Shuttle exhibit  

NASA Astrophysics Data System (ADS)

This video introduces the Pathfinder Shuttle Exhibit, a joint project between the Marshall Space Flight Center and the State of Alabama's Space and Rocket Center in Huntsville. The exhibit features a never flown Shuttle vehicle, Pathfinder, that was used in early ground tests in the Shuttle Program, as well as an actual external fuel tank and set of booster rockets. The video includes footage of actual launches, the Pathfinder Shuttle Exhibit, and shots of the Space Camp at Alabama's Space and Rocket Center.

1988-08-01

22

Abrolhos Bank Reef Health Evaluated by Means of Water Quality, Microbial Diversity, Benthic Cover, and Fish Biomass Data  

PubMed Central

The health of the coral reefs of the Abrolhos Bank (southwestern Atlantic) was characterized with a holistic approach using measurements of four ecosystem components: (i) inorganic and organic nutrient concentrations, [1] fish biomass, [1] macroalgal and coral cover and (iv) microbial community composition and abundance. The possible benefits of protection from fishing were particularly evaluated by comparing sites with varying levels of protection. Two reefs within the well-enforced no-take area of the National Marine Park of Abrolhos (Parcel dos Abrolhos and California) were compared with two unprotected coastal reefs (Sebastião Gomes and Pedra de Leste) and one legally protected but poorly enforced coastal reef (the “paper park” of Timbebas Reef). The fish biomass was lower and the fleshy macroalgal cover was higher in the unprotected reefs compared with the protected areas. The unprotected and protected reefs had similar seawater chemistry. Lower vibrio CFU counts were observed in the fully protected area of California Reef. Metagenome analysis showed that the unprotected reefs had a higher abundance of archaeal and viral sequences and more bacterial pathogens, while the protected reefs had a higher abundance of genes related to photosynthesis. Similar to other reef systems in the world, there was evidence that reductions in the biomass of herbivorous fishes and the consequent increase in macroalgal cover in the Abrolhos Bank may be affecting microbial diversity and abundance. Through the integration of different types of ecological data, the present study showed that protection from fishing may lead to greater reef health. The data presented herein suggest that protected coral reefs have higher microbial diversity, with the most degraded reef (Sebastião Gomes) showing a marked reduction in microbial species richness. It is concluded that ecological conditions in unprotected reefs may promote the growth and rapid evolution of opportunistic microbial pathogens.

Bruce, Thiago; Meirelles, Pedro M.; Garcia, Gizele; Paranhos, Rodolfo; Rezende, Carlos E.; de Moura, Rodrigo L.; Filho, Ronaldo-Francini; Coni, Ericka O. C.; Vasconcelos, Ana Tereza; Amado Filho, Gilberto; Hatay, Mark; Schmieder, Robert; Edwards, Robert; Dinsdale, Elizabeth; Thompson, Fabiano L.

2012-01-01

23

The Mars Pathfinder Mission  

Microsoft Academic Search

Mars Pathfinder, one of the first Discovery-class missions (quick, low-cost projects with focused science objectives), will land a single spacecraft with a microrover and several instruments on the sttrface of Mars in 1997. Pathfinder will be the first mission to use a rover, carrying a chemical analysis instrument, to characterize the rocks and soils in a landing area over hundreds

Matthew P. Golombek

1997-01-01

24

Assessing coral reef health across onshore to offshore stress gradients in the US Virgin Islands.  

PubMed

Managing the effects of anthropogenic disturbance on coral reefs is highly dependant on effective strategies to assess degradation and recovery. We used five years of field data in the US Virgin Islands to investigate coral reef response to a potential gradient of stress. We found that the prevalence of old partial mortality, bleaching, and all forms of coral health impairment (a novel category) increased with nearshore anthropogenic processes, such as a five-fold higher rate of clay and silt sedimentation. Other patterns of coral health, such as recent partial mortality, other diseases, and benthic cover, did not respond to this potential gradient of stress or their response could not be resolved at the frequency or scale of monitoring. We suggest that persistent signs of disturbance are more useful to short-term, non-intensive (annual) coral reef assessments, but more intensive (semi-annual) assessments are necessary to resolve patterns of transient signs of coral health impairment. PMID:18834601

Smith, T B; Nemeth, R S; Blondeau, J; Calnan, J M; Kadison, E; Herzlieb, S

2008-10-01

25

Mars Pathfinder Mission  

NSDL National Science Digital Library

The Mars Pathfinder Mission is a historic event and NASA's site offers a comprehensive account of its background, objectives, and progress. Users will find the latest news, a mission timeline, and information on the landing site and the instruments involved, including the Rover Sojourner. Additional features offered at this site include education and outreach activities for students, current data received from the spacecraft, and a realtime simulation of the Pathfinder entry, descent, and landing.

1997-01-01

26

PathFinder Science  

NSDL National Science Digital Library

PathFinder Science contains research projects about water conservation, tardigrades, a winter bird survey, ozone, ultraviolet light and DNA, global warming, spot removal, lichens, stream monitoring, amphibian biomonitoring, and particulate monitoring. Free registration to the PathFinder Science Network offers the opportunity to be a part of the listserv, upload collaborative project data or publish research work. There are tools and tips to help students publish their research on the web.

27

Use of integrated landscape indicators to evaluate the health of linked watersheds and coral reef environments in the Hawaiian islands.  

PubMed

A linkage between the condition of watersheds and adjacent nearshore coral reef communities is an assumed paradigm in the concept of integrated coastal management. However, quantitative evidence for this "catchment to sea" or "ridge to reef" relationship on oceanic islands is lacking and would benefit from the use of appropriate marine and terrestrial landscape indicators to quantify and evaluate ecological status on a large spatial scale. To address this need, our study compared the Hawai'i Watershed Health Index (HI-WHI) and Reef Health Index (HI-RHI) derived independently of each other over the past decade. Comparisons were made across 170 coral reef stations at 52 reef sites adjacent to 42 watersheds throughout the main Hawaiian Islands. A significant positive relationship was shown between the health of watersheds and that of adjacent reef environments when all sites and depths were considered. This relationship was strongest for sites facing in a southerly direction, but diminished for north facing coasts exposed to persistent high surf. High surf conditions along the north shore increase local wave driven currents and flush watershed-derived materials away from nearshore waters. Consequently, reefs in these locales are less vulnerable to the deposition of land derived sediments, nutrients and pollutants transported from watersheds to ocean. Use of integrated landscape health indices can be applied to improve regional-scale conservation and resource management. PMID:22538320

Rodgers, Ku'ulei S; Kido, Michael H; Jokiel, Paul L; Edmonds, Tim; Brown, Eric K

2012-04-27

28

Use of Integrated Landscape Indicators to Evaluate the Health of Linked Watersheds and Coral Reef Environments in the Hawaiian Islands  

NASA Astrophysics Data System (ADS)

A linkage between the condition of watersheds and adjacent nearshore coral reef communities is an assumed paradigm in the concept of integrated coastal management. However, quantitative evidence for this "catchment to sea" or "ridge to reef" relationship on oceanic islands is lacking and would benefit from the use of appropriate marine and terrestrial landscape indicators to quantify and evaluate ecological status on a large spatial scale. To address this need, our study compared the Hawai`i Watershed Health Index (HI-WHI) and Reef Health Index (HI-RHI) derived independently of each other over the past decade. Comparisons were made across 170 coral reef stations at 52 reef sites adjacent to 42 watersheds throughout the main Hawaiian Islands. A significant positive relationship was shown between the health of watersheds and that of adjacent reef environments when all sites and depths were considered. This relationship was strongest for sites facing in a southerly direction, but diminished for north facing coasts exposed to persistent high surf. High surf conditions along the north shore increase local wave driven currents and flush watershed-derived materials away from nearshore waters. Consequently, reefs in these locales are less vulnerable to the deposition of land derived sediments, nutrients and pollutants transported from watersheds to ocean. Use of integrated landscape health indices can be applied to improve regional-scale conservation and resource management.

Rodgers, Ku`ulei S.; Kido, Michael H.; Jokiel, Paul L.; Edmonds, Tim; Brown, Eric K.

2012-07-01

29

Effects of changing temperatures on coral reef health: Implications for management  

NASA Astrophysics Data System (ADS)

Human-induced climate change has already led to substantial changes in a variety of ecosystems. Coral reefs are particularly vulnerable to rises in ocean temperature as a result of climate change because they already live near their thermal limits. However, we know little about the spatial patterns of temperature anomalies, areas of greater than usual temperature, which cause coral mortality and increased rates of coral disease. These gaps in knowledge make it difficult to design effective management strategies for mitigating the effects of ocean warming. My dissertation research uses a combination of a new satellite ocean temperature dataset, field surveys on coral health, and data on marine protected area (MPA) boundaries to analyze how ocean temperatures are affecting coral reef health at regional and global scales. I discovered that temperature anomalies are spatially and temporally variable from 1985-2005 even during El Nino events. They are also typically less than 50 km2, smaller than the resolution of many climate models. In addition, I found a strong relationship on the Great Barrier Reef between the number of temperature anomalies and the number of cases of white syndrome, a prevalent coral disease. Results from this study suggest that temperature anomalies are playing a major role in the observed decline of coral reefs over the last 30-40 years. This decline highlights the importance of determining whether MPAs, one of the most common management tools are effective in restoring coral cover. My analyses demonstrated that MPAs can confer some ecosystem resilience through fisheries management and land management practices at regional scales. Coral cover on reefs inside of MPAs did not change over time, while unprotected reefs experienced declines in coral cover. However, MPAs do not moderate the effect of thermal stress on corals or reduce coral decline at rates that can offset losses from thermal stress and other major natural and human-caused disturbances. MPAs are clearly a key tool in the management of fisheries and coral reef health. My dissertation research underscores the need for both MPAs and additional measures aimed at reducing the anthropogenic activities driving climate change.

Selig, Elizabeth Rose

30

The Pathfinder System  

PubMed Central

We review highlights of our research on Pathfinder, a decision-theoretic expert system for hematopathology diagnosis. We have developed techniques for efficiently acquiring, representing, and reasoning with uncertain biomedical knowledge. Specifically, we have developed a methodology for coping with complex dependencies among findings and disease in pathology. The methodology includes an extension of the belief-network representation called similarity networks. Using this methodology, we have constructed a large probabilistic knowledge base for the domain of lymph-node pathology. We have also developed techniques for improving the clarity of explanations through the use of human-oriented abstractions. Finally, we have conducted a formal evaluation of Pathfinder's diagnostic accuracy.

Heckerman, David E.; Horvitz, Eric J.; Nathwani, Bharat N.

1989-01-01

31

Pathfinder: A Retrospective.  

National Technical Information Service (NTIS)

Mars is one of the most interesting planets in the solar system, featuring enormous canyons, giant volcanoes, and indications that, early in its history, it might have had rivers and perhaps even oceans. Five years ago, in July of 1997, the Pathfinder mis...

G. A. Landis

2002-01-01

32

Jurassic Reef Park  

NSDL National Science Digital Library

This is a bilingual, educational website from Munich, Germany. The main feature is a virtual field trip to the reefs of the Jurassic period. Besides a view of the Jurassic reefs, their builders, and their ecological settings, there is also an emphasis on the importance of modern reefs as indicators of the state-of-health of the globe and evidence of how some changes in the composition of reefs may represent the forerunners of catastrophic, regional or global, environmental change.

Leinfelder, Reinhold

33

Clues to Coral Reef Health: Integrating Radiative Transfer Modeling and Hyperspectral Data  

NASA Astrophysics Data System (ADS)

An important contribution to coral reef research is to improve spectral distinction between various health states of coral species in areas subject to harmful anthropogenic activity and climate change. New insights into radiative transfer properties of corals under healthy and stressed conditions can advance understandings of ecological processes on reefs and allow better assessments of the impacts of large-scale bleaching and disease events. Our objective is to examine the spectral and spatial properties of hyperspectral sensors that may be used to remotely sense changes in reef community health. We compare in situ reef environment spectra (healthy coral, stressed coral, dead coral, algae, and sand) with airborne hyperspectral data to identify important spectral characteristics and indices. Additionally, spectral measurements over a range of water depths, relief, and bottom types are compared to help quantify bottom-water column influences. In situ spectra was collected in July and August 2002 at the Long Rock site in the Andros Island, Bahamas coastal zone coral reef. Our primary emphasis is on Acropora palmata (or elkhorn coral), a major reef building coral, which is prevalent in the study area, but is suffering from white band disease. A. palmata is currently being proposed as an endangered species because its populations have severely declined in many areas of the Caribbean. In addition to the A. palmata biotope, we have collected spectra of at least seven other coral biotopes that exist within the study area, each with different coral community composition, density of corals, relief, and size of corals. Coral spectral reflectance is input into a radiative transfer model, CORALMOD (CM1), which is based on a leaf radiative transfer model. In CM1, input coral reflectance measurements produce modeled reflectance through an inversion at each visible wavelength to provide the absorption spectrum. Initially, we have imposed a scattering baseline that is the same regardless of the coral condition and that coral is optically thick and no light is transmitted through coral. Here we will focus on methodology, experimental design, and initial findings of the in situ spectral measurements and preliminary output from the radiative transfer model.

Guild, L.; Ganapol, B.; Kramer, P.; Armstrong, R.; Gleason, A.; Torres, J.; Johnson, L.; Garfield, N.

2002-12-01

34

The LISA Pathfinder Mission  

NASA Astrophysics Data System (ADS)

Laser Interferometer Space Antenna (LISA) Pathfinder (formerly known as SMART-2) is a European Space Agency mission designed to pave the way for the joint ESA/NASA LISA mission by testing in flight the critical technologies required for space borne gravitational wave detection; it will put two test masses in a near-perfect gravitational free-fall and control and measure their motion with unprecedented accuracy. This is achieved through technology comprising inertial sensors, high precision laser metrology, drag-free control and an ultra precise micro-Newton propulsion system. LISA Pathfinder (LPF) essentially mimics one arm of space-borne gravitational wave detectors by shrinking the million kilometer scale armlengths down to a few tens of centimeters, giving up the sensitivity to gravitational waves, but keeping the measurement technology. The scientific objective of the LPF mission consists then of the first in-flight test of low frequency gravitational wave detection metrology.

McNamara, Paul W.

2013-01-01

35

The LISA Pathfinder Mission  

NASA Astrophysics Data System (ADS)

LISA Pathfinder (formerly known as SMART-2) is an European Space Agency mission designed to pave the way for the joint ESA/NASA Laser Interferometer Space Antenna (LISA) mission by testing in flight the critical technologies required for space-borne gravitational wave detection; it will put two test masses in a near-perfect gravitational free-fall and control and measure their motion with unprecedented accuracy. This is achieved through technology comprising inertial sensors, high precision laser metrology, drag-free control, and an ultra precise micro-Newton propulsion system. LISA Pathfinder (LPF) essentially mimics one arm of spaceborne gravitational wave detectors by shrinking the million kilometre scale armlengths down to a few tens of centimetres, giving up the sensitivity to gravitational waves, but keeping the measurement technology. The scientific objective of the LISA Pathfinder mission consists then of the first in-flight test of low frequency gravitational wave detection metrology. In this paper I will give a brief overview of the mission, focusing on scientific and technical goals.

McNamara, P.; Antonucci, F.; Armano, M.; Audley, H.; Auger, G.; Benedetti, M.; Binetruy, P.; Bogenstahl, J.; Bortoluzzi, D.; Brandt, N.; Caleno, M.; Cavalleri, A.; Congedo, G.; Cruise, M.; Danzmann, K.; De Marchi, F.; Diaz-Aguilo, M.; Diepholz, I.; Dixton, G.; Dolesi, R.; Dumbar, N.; Fauste, J.; Ferraioli, L.; Ferroni, V.; Fichter, W.; Fitzsimons, E.; Freschi, M.; García Marirrodriga, C.; Gerndt, R.; Gesa, L.; Gibert, F.; Giardini, D.; Grimani, C.; Grynagier, A.; Guzmán, F.; Harrison, I.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hoyland, D.; Hueller, M.; Huesler, J.; Jennrich, O.; Jetzer, P.; Johlander, B.; Karnesis, N.; Korsakova, N.; Killow, C.; Llamas, X.; Lloro, I.; Lobo, A.; Maarschalkerweerd, R.; Madden, S.; Mance, D.; Martin, V.; Mateos, I.; Mendes, J.; Mitchell, E.; Nicolodi, D.; Nofrarias, M.; Perreur-Lloyd, M.; Plagnol, E.; Prat, P.; Ramos-Castro, J.; Reiche, J.; Romera Perez, J. A.; Robertson, D.; Rozemeijer, H.; Russano, G.; Schleicher, A.; Shaul, D.; Sopuerta, C. F.; Sumner, T. J.; Taylor, A.; Texier, D.; Trenkel, C.; Tu, H. B.; Vitale, S.; Wanner, G.; Ward, H.; Waschke, S.; Wass, P.; Wealthy, D.; Wen, S.; Weber, W.; Ziegler, T.; Zweifel, P.

2013-01-01

36

Reef grief  

NASA Astrophysics Data System (ADS)

As the first of the world's ecosystems faces extermination at our hands, coral reef ecologist Peter Sale -- Assistant Director of the Institute of Water, Environment and Health at the United Nations University in Ontario, Canada, and author of Our Dying Planet (published this autumn) -- talks to Nature Climate Change.

2011-10-01

37

The Mars Pathfinder Mission  

NASA Astrophysics Data System (ADS)

The Mars Pathfinder mission is a Discovery class mission that will place a small lander and rover on the surface of Mars on July 4, 1997. The Pathfinder flight system is a single small lander, packaged within an aeroshell and back cover with a back-pack-style cruise stage. The vehicle will be launched, fly independently to Mars, and enter the atmosphere directly on approach behind the aeroshell. The vehicle is slowed by a parachute and 3 small solid rockets before landing on inflated airbags. Petals of a small tetrahedron shaped lander open up, to right the vehicle. The lander is solar powered with batteries and will operate on the surface for up to a year, downlinking data on a high-gain antenna. Pathfinder will be the first mission to use a rover, with 3 imagers and an alpha proton X-ray spectrometer, to characterize the rocks and soils in a landing area over hundreds of square meters on Mars, which will provide a calibration point or "ground truth" for orbital remote sensing observations. The rover (includes a series of technology experiments), the instruments (including a stereo multispectral surface imager on a pop up mast and an atmospheric structure instrument-surface meteorology package) and the telemetry system will allow investigations of: the surface morphology and geology at meter scale, the petrology and geochemistry of rocks and soils, the magnetic properties of dust, soil mechanics and properties, a variety of atmospheric investigations and the rotational and orbital dynamics of Mars. Landing downstream from the mouth of a giant catastrophic outflow channel, Ares Vallis, offers the potential of identifying and analyzing a wide variety of crustal materials, from the ancient heavily cratered terrain, intermediate-aged ridged plains and reworked channel deposits, thus allowing first-order scientific investigations of the early differentiation and evolution of the crust, the development of weathering products and early environments and conditions on Mars.

Golombek, M. P.

1996-09-01

38

Cytokines Online Pathfinder Encyclopaedia  

NSDL National Science Digital Library

The Cytokines Online Pathfinder Encyclopaedia (COPE) is the brainchild of Horst Ibelgaufts of Germany's Ludwig-Maximilians-Universit't Gene Center. Part super-glossary, part general guide to the "jungles, morasses, and deserts of cytokine-land," this incredibly extensive Web site helps researchers stay on top of newly identified proteins and previously identified but recently reevaluated proteins. As of February 2003, COPE contains over 8,700 entries, which have been mercifully grouped into sub-glossaries by subject: apoptosis, cell lines, chemokines, cytokine topics, hematology, metalloproteinases virokines, viroceptors, and virulence factors.

1997-01-01

39

The LISA Pathfinder Mission  

NASA Astrophysics Data System (ADS)

LISA Pathfinder is a mission of the European Space Mission aimed at demonstrating the space-time metrology required for space-borne gravitational wave observatories like eLISA. In particular the mission aims at experimentally test the detailed physical model of the eLISA instrument using the hardware to be flown on eLISA. This model predicts that no true forces on test-bodies will compete with gravitational signals in excess to fN/Hz^(-1/2). The mission is in phase C/D and is due to launch in two years. The talk will describe the mission, its development status, and the metrology under test.

Vitale, Stefano; LISA Pathfinder Team

2013-04-01

40

National pathfinder survey on children's oral health in Italy: pattern and severity of caries disease in 4-year-olds.  

PubMed

This paper describes the dental health status of Italian 4-year-olds in 2004/2005 and analyzes the association between caries in preschool children and some background characteristics in children and parents. Caries was recorded according to WHO criteria. 5,538 subjects were examined. Information on the children's and their parents' social, behavioral, ethnic and demographic status was obtained through a series of closed questions. Bivariate analysis was performed to investigate the association between caries and background characteristics. The probability of being an extra zero for the dmfs index was estimated via the zero-inflated negative binomial regression model (ZINB). 78.4% (95% CI = 77.2-79.6) of the children were caries-free. The national mean dmfs index was 1.36 (95% CI = 1.15-1.57), ranging from 1.22 (95% CI = 1.03-1.42) in the Italian North-East to 1.73 (95% CI = 0.83-2.63) in the South section. Significant bivariate associations between caries experience and risk factors were observed for parents' nationality (not Italian vs. Italian: p < 0.001), parents' educational levels (low vs. high: p < 0.001), preterm birth (yes vs. no: p = 0.011), prolonged breastfeeding (13 months: p = 0.038) and early tooth eruption (<6 months as reference: p = 0.004). Multivariable analysis (ZINB) showed that children with a low caries risk level had a higher probability of being an extra zero; in particular, children from fathers with a high educational level showed a probability of being an extra zero of 0.22. The results suggest a need to plan preventive programs to reduce oral health disparities among Italian preschool children, based on educational intervention with parents and children concerning oral health and caries prevention. PMID:19365120

Campus, G; Solinas, G; Strohmenger, L; Cagetti, M G; Senna, A; Minelli, L; Majori, S; Montagna, M T; Reali, D; Castiglia, P

2009-04-08

41

Photodiode Performance for LISA Pathfinder  

NASA Astrophysics Data System (ADS)

The InGaAs photodiodes procured for LISA Pathfinder have been subject to a formal qualifi-cation programme and a series of optical calibration and performance tests. The photometric response and uniformity has been calibrated using a specialised facility at the University of Birmingham. The results for the flight and flight spare photodiodes are presented and the influence on the performance of LISA Pathfinder will be analysed.

Cruise, Mike; Dixon, George; Hoyland, David

42

Mission design for LISA Pathfinder  

Microsoft Academic Search

Here we describe the mission design for SMART-2\\/LISA Pathfinder. The best trade-off between the requirements of a low-disturbance environment and communications distance is found to be a free-insertion Lissajous orbit around the first collinear Lagrange point of the Sun Earth system (L1), 1.5 × 106 km from Earth. In order to transfer SMART-2\\/LISA Pathfinder from a low Earth orbit, where

M. Landgraf; M. Hechler; S. Kemble

2005-01-01

43

A model of the effects of land-based, human activities on the health of coral reefs in the Great Barrier Reef and in Fouha Bay, Guam, Micronesia  

Microsoft Academic Search

A model is proposed to explain coral and algal abundance on coastal coral reefs as a function of spike-like natural disturbances from tropical cyclones and turbid river floods, followed by long recovery periods where the rate of reef recovery depends on ambient water and substratum quality. The model includes competition for space between corals and algae, coral recruitment and reef

Eric Wolanski; Robert H. Richmond; Laurence McCook

2004-01-01

44

Mars Pathfinder's lessons learned from the Mars Pathfinder Project Manager's perspective and the future road  

Microsoft Academic Search

This paper addresses Mars Pathfinder Project lessons learned from a Project Management perspective. Also, it contrasts the Future Project Development approach relative to the Mars Pathfinder's approach.Mars Pathfinder was initiated by NASA in March 1992 as an experiment in CHEAPER, BETTER, FASTER.Not only was the Mars Pathfinder Team challenged to land on Mars-- no easy task-- but they were asked

1999-01-01

45

The LISA Pathfinder Radiation Monitor  

SciTech Connect

We present the concept, design and testing of the radiation monitor for LISA Pathfinder. Galactic cosmic rays (GCRs) and solar energetic particles (SEPs) will cause charging of the LISA Pathfinder test masses producing unwanted disturbances which could be significant during a large solar eruption. A radiation monitor on board LISA Pathfinder, using silicon PIN diodes as particle detectors, will measure the particle flux responsible for charging. It will also be able to record spectral information to identify solar energetic particle events. The design of the monitor was supported by Monte Carlo simulations which allow detailed predictions of the radiation monitor performance. We present these predictions as well as the results of high-energy proton tests carried out at the Paul Scherrer Institute, Switzerland. The tests show good agreement with our simulations and confirm the capability of the radiation monitor to perform well in the space environment, meeting all science requirements.

Wass, P. J.; Araujo, H.; Sumner, T. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London, SW7 2AZ (United Kingdom); Boatella, C.; Lobo, A. [Institut d'Estudis Espacials de Catalunya (IEEC), Barcelona (Spain); Chmeissani, M.; Puigdengoles, C. [Intsitut de Fisica d'Altes Energies (IFAE), Barcelona (Spain); Hajdas, W. [Paul Scherrer Institut, Villigen (Switzerland)

2006-11-29

46

The development of an integrated systems model for balancing coral reef health, land management and tourism risks on the Great Barrier Reef  

Microsoft Academic Search

A prototype Bayesian belief network (BBN) is described that provides catchment-to-reef integration of previously unlinked components of the Great Barrier Reef (GBR) social-ecological system. The BBN is developed to help decision-makers understand the socio-economic trade-offs associated with managing for resilient reef communities given the threat posed by climate change. The probability of severe coral bleaching events increases with climate-driven increases

I. J. Gordon; S. Wooldridge; M. van Grieken; P. Marshall; Barrier Reef

47

Gravitational science with LISA Pathfinder  

Microsoft Academic Search

We investigate the potential of conducting interesting gravitational science experiments with LISA Pathfinder, by executing well defined de-orbiting manoeuvres following the nominal mission. Preliminary work suggests that the residual control authority of the micropropulsion system is sufficient to follow trajectories that cross the region surrounding the Sun-Earth saddle point, and also include one or multiple Earth flybys. Crossing the saddle

C. Trenkel; S. Kemble

2009-01-01

48

LISA Pathfinder: mission and status  

Microsoft Academic Search

LISA Pathfinder, the second of the European Space Agency's Small Missions for Advanced Research in Technology (SMART), is a dedicated technology demonstrator for the joint ESA\\/NASA Laser Interferometer Space Antenna (LISA) mission. The technologies required for LISA are many and extremely challenging. This coupled with the fact that some flight hardware cannot be fully tested on ground due to Earth-induced

F. Antonucci; M. Armano; H. Audley; G. Auger; M. Benedetti; P. Binetruy; C. Boatella; J. Bogenstahl; D. Bortoluzzi; P. Bosetti; M. Caleno; A. Cavalleri; M. Cesa; M. Chmeissani; G. Ciani; A. Conchillo; G. Congedo; I. Cristofolini; M. Cruise; K. Danzmann; F. De Marchi; M. Diaz-Aguilo; I. Diepholz; G. Dixon; R. Dolesi; N. Dunbar; J. Fauste; L. Ferraioli; D. Fertin; W. Fichter; E. Fitzsimons; M. Freschi; A. García Marin; C. García Marirrodriga; R. Gerndt; L. Gesa; F. Gilbert; D. Giardini; C. Grimani; A. Grynagier; B. Guillaume; F. Guzmán; I. Harrison; G. Heinzel; M. Hewitson; D. Hollington; J. Hough; D. Hoyland; M. Hueller; J. Huesler; O. Jeannin; O. Jennrich; P. Jetzer; B. Johlander; C. Killow; X. Llamas; I. Lloro; A. Lobo; R. Maarschalkerweerd; S. Madden; D. Mance; I. Mateos; P. W. McNamara; J. Mendes; E. Mitchell; A. Monsky; D. Nicolini; D. Nicolodi; M. Nofrarias; F. Pedersen; M. Perreur-Lloyd; A. Perreca; E. Plagnol; P. Prat; G. D. Racca; B. Rais; J. Ramos-Castro; J. Reiche; J. A. Romera Perez; D. Robertson; H. Rozemeijer; J. Sanjuan; A. Schleicher; M. Schulte; D. Shaul; L. Stagnaro; S. Strandmoe; F. Steier; T. J. Sumner; A. Taylor; D. Texier; C. Trenkel; D. Tombolato; S. Vitale; G. Wanner; H. Ward; S. Waschke; P. Wass; W. J. Weber; P. Zweifel

2011-01-01

49

Pathfinder Teaching and Learning Units.  

ERIC Educational Resources Information Center

|This collection of teaching units were selected from materials developed during the Operation Pathfinder Institutes (OPI) which took place in the Pacific region between 1994 and 1999. The institutes were intended to provide upper elementary and middle school science teachers with an opportunity to develop a deeper understanding of the marine…

Hawaii Univ., Honolulu. Sea Grant Program.

50

APEX: the Atacama Pathfinder EXperiment  

Microsoft Academic Search

APEX, the Atacama Pathfinder Experiment, has been successfully commissioned and is in operation now. This novel submillimeter telescope is located at 5107 m altitude on Llano de Chajnantor in the Chilean High Andes, on what is considered one of the world's outstanding sites for submillimeter astronomy. The primary reflector with 12 m diameter has been carefully adjusted by means of

R. Güsten; R. S. Booth; C. Cesarsky; K. M. Menten; C. Agurto; M. Anciaux; F. Azagra; V. Belitsky; A. Belloche; P. Bergman; C. De Breuck; C. Comito; M. Dumke; C. Duran; W. Esch; J. Fluxa; A. Greve; H. Hafok; W. Häupl; L. Helldner; A. Henseler; S. Heyminck; L. E. Johansson; C. Kasemann; B. Klein; A. Korn; E. Kreysa; R. Kurz; I. Lapkin; S. Leurini; D. Lis; A. Lundgren; M. Martinez; J. Melnick; D. Morris; D. Muders; L. A. Nyman; M. Olberg; R. Olivares; M. Pantaleev; N. Patel; K. Pausch; S. D. Philipp; S. Philipps; T. K. Sridharan; E. Polehampton; V. Reveret; C. Risacher; M. Roa; P. Sauer; P. Schilke; J. Santana; G. Schneider; J. Sepulveda; G. Siringo; J. Spyromilio; K.-H. Stenvers; F. van der Tak; D. Torres; L. Vanzi; V. Vassilev; A. Weiss; K. Willmeroth; A. Wunsch; F. Wyrowski

2006-01-01

51

The Sonic Pathfinder: An Evaluation.  

ERIC Educational Resources Information Center

|An objective evaluation of the Sonic Pathfinder, a new ultrasonic mobility aid, showed that use of the aid changes mobility in many ways. Reduced perception of environmental sounds was not reflected in performance. The majority of users traveled slowly and exhibited less than optimal strategies. (Author/CL)|

Dodds, Allan G.; And Others

1984-01-01

52

Spacetime Metrology with LISA Pathfinder  

NASA Astrophysics Data System (ADS)

LISA is the proposed ESA-NASA gravitational wave detector in the 0.1 mHz - 0.1 Hz band. LISA Pathfinder is the down-scaled version of a single LISA arm. The arm - named Doppler link - can be treated as a differential accelerometer, measuring the relative acceleration between test masses. LISA Pathfinder - the in-flight test of the LISA instrumentation - is currently in the final implementation and planned to be launched in 2014. It will set stringent constraints on the ability to put test masses in geodesic motion to within the required differential acceleration of 3times10^{-14} m s^{-2} Hz^{-1/2} and track their relative motion to within the required differential displacement measurement noise of 9times10^{-12} m Hz^{-1/2}, around 1 mHz. Given the scientific objectives, it will carry out - for the first time with such high accuracy required for gravitational wave detection - the science of spacetime metrology, in which the Doppler link between two free-falling test masses measures the curvature. This thesis contains a novel approach to the calculation of the Doppler response to gravitational waves. It shows that the parallel transport of 4-vectors records the history of gravitational wave signals. In practice, the Doppler link is implemented with 4 bodies in LISA and 3 bodies in LISA Pathfinder. To compensate for noise sources a control logic is implemented during the measurement. The closed-loop dynamics of LISA Pathfinder can be condensed into operators acting on the motion coordinates, handling the couplings, as well as the cross-talks. The scope of system identification is the optimal calibration of the instrument. This thesis describes some data analysis procedures applied to synthetic experiments and shows the relevance of system identification for the success of LISA Pathfinder in demonstrating the principles of spacetime metrology for all future space-based missions.

Congedo, Giuseppe

2012-04-01

53

Desert Pathfinder at Work  

NASA Astrophysics Data System (ADS)

The Atacama Pathfinder Experiment (APEX) project celebrates the inauguration of its outstanding 12-m telescope, located on the 5100m high Chajnantor plateau in the Atacama Desert (Chile). The APEX telescope, designed to work at sub-millimetre wavelengths, in the 0.2 to 1.5 mm range, passed successfully its Science Verification phase in July, and since then is performing regular science observations. This new front-line facility provides access to the "Cold Universe" with unprecedented sensitivity and image quality. After months of careful efforts to set up the telescope to work at the best possible technical level, those involved in the project are looking with satisfaction at the fruit of their labour: APEX is not only fully operational, it has already provided important scientific results. "The superb sensitivity of our detectors together with the excellence of the site allow fantastic observations that would not be possible with any other telescope in the world," said Karl Menten, Director of the group for Millimeter and Sub-Millimeter Astronomy at the Max-Planck-Institute for Radio Astronomy (MPIfR) and Principal Investigator of the APEX project. ESO PR Photo 30/05 ESO PR Photo 30/05 Sub-Millimetre Image of a Stellar Cradle [Preview - JPEG: 400 x 627 pix - 200k] [Normal - JPEG: 800 x 1254 pix - 503k] [Full Res - JPEG: 1539 x 2413 pix - 1.3M] Caption: ESO PR Photo 30/05 is an image of the giant molecular cloud G327 taken with APEX. More than 5000 spectra were taken in the J=3-2 line of the carbon monoxide molecule (CO), one of the best tracers of molecular clouds, in which star formation takes place. The bright peak in the north of the cloud is an evolved star forming region, where the gas is heated by a cluster of new stars. The most interesting region in the image is totally inconspicuous in CO: the G327 hot core, as seen in methanol contours. It is a truly exceptional source, and is one of the richest sources of emission from complex organic molecules in the Galaxy (see spectrum at bottom). Credit: Wyrowski et al. (map), Bisschop et al. (spectrum). Millimetre and sub-millimetre astronomy opens exciting new possibility in the study of the first galaxies to have formed in the Universe and of the formation processes of stars and planets. In particular, APEX allows astronomers to study the chemistry and physical conditions of molecular clouds, that is, dense regions of gas and dust in which new stars are forming. Among the first studies made with APEX, astronomers took a first glimpse deep into cradles of massive stars, observing for example the molecular cloud G327 and measuring significant emission in carbon monoxide and complex organic molecules (see ESO PR Photo 30/05). The official inauguration of the APEX telescope will start in San Pedro de Atacama on September, 25th. The Ambassadors in Chile of some of ESO's member states, the Intendente of the Chilean Region II, the Mayor of San Pedro, the Executive Director of the Chilean Science Agency (CONICYT), the Presidents of the Communities of Sequitor and Toconao, as well as representatives of the Ministry of Foreign Affairs and Universities in Chile, will join ESO's Director General, Dr. Catherine Cesarsky, the Chairman of the APEX Board and MPIfR director, Prof. Karl Menten, and the Director of the Onsala Space Observatory, Prof. Roy Booth, in a celebration that will be held in San Pedro de Atacama. The next day, the delegation will visit the APEX base camp in Sequitor, near San Pedro, from where the telescope is operated, as well as the APEX site on the 5100m high Llano de Chajnantor.

2005-09-01

54

Mission design for LISA Pathfinder  

NASA Astrophysics Data System (ADS)

Here we describe the mission design for SMART-2/LISA Pathfinder. The best trade-off between the requirements of a low-disturbance environment and communications distance is found to be a free-insertion Lissajous orbit around the first collinear Lagrange point of the Sun Earth system (L1), 1.5 × 106 km from Earth. In order to transfer SMART-2/LISA Pathfinder from a low Earth orbit, where it will be placed by a small launcher, the spacecraft carries out a number of apogee-raise manoeuvres, which ultimatively place it to a parabolic escape trajectory towards L1. The challenges of the design of a small mission are met, fulfilling the very demanding technology demonstration requirements without creating excessive requirements on the launch system or the ground segment.

Landgraf, M.; Hechler, M.; Kemble, S.

2005-05-01

55

Viruses in coral reef ecosystems: implications for nutrient cycling and coral health  

Microsoft Academic Search

Viruses are abundant and ubiquitous across aquatic ecosystems; they infect organisms ranging in size from bacteria to whales, and have important roles in biogeochemical processes. However, one ecosystem where information regarding viral ecology is limited is in coral reefs. Consequently, the main objective of this thesis was to increase our understanding of the presence and roles of viruses in coral

Nicole L Patten

2008-01-01

56

Devonian reefs  

SciTech Connect

Three reef settings in northern Alberta and British Columbia were examined: (1) shelf edge, in the Clarke Lake shale basin; (2) open-marine pinnacle, in the Clarke Lake shale basin; and (3) restricted basin pinnacle, in the Shekilie evaporite basin. The shelf-edge reef tends to be water prone and does not offer the same reserves potential as pinnacle reefs; therefore, it is not examined in detail. The pinnacle reefs in the open-marine setting tend to be gas prone, whereas the pinnacle reefs in the restricted basin setting tend to be oil prone. Seismic models were generated from geologic cross sections over existing, economically producing reef anomalies. Seismic responses from these models were then examined, and criteria for reef identification established. For the acid test, seismic anomalies that were tested by the drill bit were examined, and the validity of the reef identification criteria was confirmed. Examples include both economic successes and failures. A different set of criteria for pinnacle reef identification were established for open-marine and restricted basin settings. Criteria are not universally applicable, so each basin will have a different set. Detecting the content and amount of porosity in reefs using seismic studies is elusive at best and remains a challenge to the explorationist.

Kuhme, A.K.

1986-05-01

57

PATHFINDER ATOMIC POWER PLANT ANALOG SIMULATOR  

Microsoft Academic Search

The steady-state and dynamlc characterlstics of the Pathfinder systems ; were simulated on a dual-console Pace Analog Computer. The derivation of the ; system equations, the assumptions involved, their numerical evaluation, and their ; conversion to analog circuitry are described. The Pathfinder system is unique ; because of the internal nuclear superheater, and controlled, forced recirculation. ; In simulating this

D. H. Crimmins; D. Mohr; J. T. Stone

1962-01-01

58

PATHFINDER ATOMIC POWER PLANT STEAM SEPARATOR DEVELOPMENT  

Microsoft Academic Search

Development of a steam separator the Pathfinder Reactor is reported. ; A full-scale separator model was developed through the combination of scale-model ; testing and the application of principles associated with the existing theory of ; centrifugal separation. This model was put through full-scale air-water tests ; which led to modifications and a final design which meets Pathfinder requirements. ;

G. C. Kutsch; D. H. Swanson; H. W. Yant

1962-01-01

59

Internet Public Library: Pathfinders  

NSDL National Science Digital Library

This useful resource from the Internet Public Library makes available "home-grown guides written by IPL staff which are intended to help you get started doing research on a particular topic, both online and at your local library." There are currently over one hundred guides with new ones posted regularly. The guides are listed under broad subject categories, which include Arts and Humanities; Health, Medicine and Nutrition; History and War; Business and Consumers; Science and Technology; Education and Libraries; Law, Politics, and Government; Society and Culture; Entertainment, Leisure, and Hobbies; and others. The guides are individually organized, but all feature print and Internet resources (the latter with annotations) as well as "getting started" advice (including Internet search strategies). They also include governmental, academic, and institutional resources -- both on and off the Web -- where relevant.

1995-01-01

60

Dust devils as observed by Mars Pathfinder  

NASA Astrophysics Data System (ADS)

Dust devils are localized meteorological phenomena frequently observed in terrestrial dry lands and desert landscapes as well as on Mars. They are low-pressure, warm core vortices that form at the bottom of convective plumes and loft dust from the surface. They move with the speed of the ambient wind and are tilted by wind shears. The Mars Pathfinder detected dust devils as dust plumes in the Imager for Mars Pathfinder images and as low-pressure convective vortices in the meteorological Mars Pathfinder Atmospheric Structure Investigation/Meteorology (ASI/MET) experiment data. The Pathfinder data have been analyzed in terms of dust devil size, spatial distribution, and frequency of occurrence. The results show that the Pathfinder imaging and MET observations are consistent with each other and with the observations made by the Viking 1 Orbiter and Mars Global Surveyor. The dust devil's ability to loft dust into the atmosphere has been investigated and a thermodynamic theory for dust devils has been used to calculate their physical parameters relevant to dust transport. The dust devils observed in an active day provide a pumping rate larger than the dust-settling rate derived from the optical obscuration of the Pathfinder rover solar panels. Therefore dust devils are a major factor in transporting dust from the surface to the atmosphere at the Pathfinder site.

Ferri, Francesca; Smith, Peter H.; Lemmon, Mark; Rennó, Nilton O.

2003-12-01

61

Mars Pathfinder airbag impact attenuation system.  

National Technical Information Service (NTIS)

The Mars Pathfinder spacecraft, scheduled for launch in November 1996, is designed to validate a low cost Entry, Descent, and Landing system and to perform scientific surface operations. The Jet Propulsion Laboratory and Sandia National Laboratories teame...

D. E. Waye J. K. Cole T. P. Rivellini

1995-01-01

62

Testing Modified Newtonian Dynamics with LISA Pathfinder  

NASA Astrophysics Data System (ADS)

We suggest that LISA Pathfinder, a technology demonstrator for the future gravitational wave observatory LISA, could be used to carry out a direct experimental test of Modified Newtonian Dynamics (MOND). The LISA Pathfinder spacecraft is currently being built and the launch date is just a few years away. No modifications of the spacecraft are required, nor any interference with its nominal mission. The basic concept is to fly LISA Pathfinder through the region around the Sun-Earth saddle point, in an extended mission phase, once the original mission goals are achieved. We examine various strategies to reach the saddle point, and find that the preferred strategy, yielding relatively short transfer times of just over 1 year, probably involves a lunar fly-by. LISA Pathfinder will be able to probe the intermediate MOND regime, i.e. the transition between deep MOND and Newtonian gravity. We present robust estimates of the anomalous gravity gradients that LISA Pathfinder should be exposed to, based on MONDian effects as derived from the Tensor-Vector-Scalar (TeVeS) theory. The spacecraft speed and spatial scale of the MOND signal combine in a way that the spectral signature of the signal falls precisely into LISA Pathfinder's measurement bandwidth. We find that if the gravity gradiometer on-board the spacecraft achieves its currently predicted sensitivity, these anomalous gradients could not just be detected, but measured in some detail.

Trenkel, Christian; Kemble, Steve; Bevis, Neil; Magueijo, Joao

2012-12-01

63

New Caledonia surface lagoon chlorophyll modeling as coastal reef area health indicator  

NASA Astrophysics Data System (ADS)

The major part of the New Caledonia (NC) lagoon was classified as UNESCO Natural Site of Humanity Patrimony. Indeed, 22 175 km2 of tropical coral lagoon area exhibit high biodiversity. The NC lagoon is semi enclosed and connected to the Coral Sea through a barrier reef segmented by narrow passes. The environment is oligotrophic, due to important flush during trade winds events, and bathymetry is highly variable. In order to predict eutrophication events, we used an extension of a 3D coupled physical-biogeochemical model recently developed on NC south western lagoon. The model is based on the Nitrogen and Carbon cycles, relating the variable stoechiometry of the elements in each biological compartment. The ecological model was developed to include an explicit description of the microbial loop. The resulting coupled model, forced by tide, wind, light, temperature and freshwater inputs, was used to calculate phytoplankton biomass, bacterial production, dissolved organic matter concentrations and nutrient recycling. Here we present results issued from the 3D coupled model ECO3M_LAGOON (biogeochemical, LOPB-IRD) and MARS3D (regional physical model, IFREMER-IRD) describing spatial and temporal interactions between water motion and biology, on larger domain including reef barrier and water exchanges through ocean-lagoon interface. To validate physical processes in the lagoon we used in situ data collected during field cruise (ValHyBio 2008, La Niña episode). Surface chlorophyll concentrations are compared with water color data from ValHyBio cruise and satellite data (MODIS/MERIS) corrected from bathymetry effects.

Fuchs, R.; Pinazo, C.; Douillet, P.; Dupouy, C.; Faure, V.; Mangin, A.

2010-10-01

64

Dynamic Pathfinders: Leveraging Your OPAC to Create Resource Guides  

ERIC Educational Resources Information Center

Library pathfinders are a time-tested method of leading library users to important resources. However, paper-based pathfinders suffer from space limitations, and both paper-based and Web-based pathfinders require frequent updates to keep up with new library acquisitions. This article details a step-by-step method to create an online dynamic…

Hunter, Ben

2008-01-01

65

Dynamic Pathfinders: Leveraging Your OPAC to Create Resource Guides  

ERIC Educational Resources Information Center

|Library pathfinders are a time-tested method of leading library users to important resources. However, paper-based pathfinders suffer from space limitations, and both paper-based and Web-based pathfinders require frequent updates to keep up with new library acquisitions. This article details a step-by-step method to create an online dynamic…

Hunter, Ben

2008-01-01

66

Mars Pathfinder Rover-Lewis Research Center Technology Experiments Program  

Microsoft Academic Search

An overview of NASA's Mars Pathfinder Program is given and the development and role of three technology experiments from NASA's Lewis Research Center and carried on the Mars Pathfinder rover is described. Two recent missions to Mars were developed and managed by the Jet Propulsion Laboratory, and launched late last year: Mars Global Surveyor in November 1996 and Mars Pathfinder

Steven M. Stevenson

1997-01-01

67

The Mars Pathfinder Outreach Project: A Rural Model  

Microsoft Academic Search

The Montana Mars Pathfinder Outreach Project (MPOP) has completed a successful year of interactive presentations with K-12 students across the west. Carefully selected Montana State University undergraduates visited over 4000 students in the year preceding the Pathfinder landing on Mars. Each presentation showcased a computer generated video of the Pathfinder launch and mission and a slide set about Mars along

Shane L. Larson; Michelle B. Larson; William A. Hiscock

1998-01-01

68

Research on Teacher-Librarian' ICT Education Skills using Pathfinder  

Microsoft Academic Search

In this paper, we studied the correlation between the teacher-librarian's ICT literacy, pathfinder and ICT skills. Pathfinders were marked and ICT skills were learned through questionnaire. The object of the study was to learn the correlation between teachers, those who make a good pathfinder, and those who can evaluate and make good use of ICT as adequate teaching materials in

Toru FUKUMOTO

69

Which Environmental Factors Predict Seasonal Variation in the Coral Health of Acropora digitifera and Acropora spicifera at Ningaloo Reef?  

PubMed Central

The impact of physico-chemical factors on percent coral cover and coral health was examined on a spatial basis for two dominant Acropora species, A. digitifera and A. spicifera, at Ningaloo Reef (north-western Australia) in the southeast Indian Ocean. Coral health was investigated by measuring metabolic indices (RNA/DNA ratio and protein concentration), energy levels (lipid ratio) and autotrophic indices (chlorophyll a (chl a) and zooxanthellae density) at six stations during typical seasons (austral autumn 2010 (March and April), austral winter 2010 (August)) and during an extreme La Niña event in summer 2011 (February). These indices were correlated with 15 physico-chemical factors (measured immediately following coral sampling) to identify predictors for health indices. Variations in metabolic indices (protein concentration and RNA/DNA ratio) for A. spicifera were mainly explained by nitrogen, temperature and zooplankton concentrations under typical conditions, while for A. digitifera, light as well as phytoplankton, in particular picoeukaryotes, were important, possibly due to higher energy requirement for lipid synthesis and storage in A. digitifera. Optimum metabolic values occurred for both Acropora species at 26–28°C when autotrophic indices (chl a and zooxanthellae density) were lowest. The extreme temperature during the La Niña event resulted in a shift of feeding modes, with an increased importance of water column plankton concentrations for metabolic rates of A. digitifera and light and plankton for A. spicifera. Our results suggest that impacts of high sea surface temperatures during extreme events such as La Niña may be mitigated via reduction on metabolic rates in coral host. The high water column plankton concentrations and associated low light levels resulted in a shift towards high symbiont densities, with lower metabolic rates and energy levels than the seasonal norm for the coral host.

Hinrichs, Saskia; Patten, Nicole L.; Feng, Ming; Strickland, Daniel; Waite, Anya M.

2013-01-01

70

Which environmental factors predict seasonal variation in the coral health of Acropora digitifera and Acropora spicifera at Ningaloo Reef?  

PubMed

The impact of physico-chemical factors on percent coral cover and coral health was examined on a spatial basis for two dominant Acropora species, A. digitifera and A. spicifera, at Ningaloo Reef (north-western Australia) in the southeast Indian Ocean. Coral health was investigated by measuring metabolic indices (RNA/DNA ratio and protein concentration), energy levels (lipid ratio) and autotrophic indices (chlorophyll a (chl a) and zooxanthellae density) at six stations during typical seasons (austral autumn 2010 (March and April), austral winter 2010 (August)) and during an extreme La Niña event in summer 2011 (February). These indices were correlated with 15 physico-chemical factors (measured immediately following coral sampling) to identify predictors for health indices. Variations in metabolic indices (protein concentration and RNA/DNA ratio) for A. spicifera were mainly explained by nitrogen, temperature and zooplankton concentrations under typical conditions, while for A. digitifera, light as well as phytoplankton, in particular picoeukaryotes, were important, possibly due to higher energy requirement for lipid synthesis and storage in A. digitifera. Optimum metabolic values occurred for both Acropora species at 26-28°C when autotrophic indices (chl a and zooxanthellae density) were lowest. The extreme temperature during the La Niña event resulted in a shift of feeding modes, with an increased importance of water column plankton concentrations for metabolic rates of A. digitifera and light and plankton for A. spicifera. Our results suggest that impacts of high sea surface temperatures during extreme events such as La Niña may be mitigated via reduction on metabolic rates in coral host. The high water column plankton concentrations and associated low light levels resulted in a shift towards high symbiont densities, with lower metabolic rates and energy levels than the seasonal norm for the coral host. PMID:23637770

Hinrichs, Saskia; Patten, Nicole L; Feng, Ming; Strickland, Daniel; Waite, Anya M

2013-04-23

71

Periodontal status among adolescents in Georgia. A pathfinder study  

PubMed Central

Objectives. The aim of the present pathfinder study was to screen and map the periodontal status of Georgian population in accordance with the guidelines of the World Health Organization for population based surveys. Methods. During 2012, a pathfinder study was conducted to collect this data. For the periodontal portion of the study, 15-year-old school children were examined in the capital city of Tbilisi as well as in two other large cities and 4 smaller villages. All participants were examined by a trained dental team in a classroom using a dental mirror and a periodontal probe. Periodontal examination included plaque scores, calculus scores, probing depth measurements and bleeding on probing. These measurements were recorded for the Ramfjord index teeth. Results. A total of 397 15-year-old participants were examined in this pathfinder study. There were 240 females (60.45%) and 157 males (39.55%). Of the total participants 196 (49.37%) were urban adolescents while 201 (50.63%) were from rural communities. Mean probing depth was 3.34 ± 0.57 mm with a range of 1 to 10 mm; a relatively high proportion (34.26%) of these subjects presented with at least one site with pockets of 5 mm or deeper. Males presented with greater plaque, calculus and probing depths than females. When urban and rural populations were compared, urban participants presented with more plaque, probing depths and bleeding on probing. Greater pocket depths were found to be related to the presence of plaque calculus and bleeding on probing. Conclusions. Overall, rather high incidences of periodontal pockets ? 5 mm were detected in this population. This data should serve to prepare further more detailed epidemiological studies that will serve to plan and implement prevent and treat strategies for periodontal diseases in Georgia and also help make manpower decisions.

Margvelashvili, Vladimer; Bilder, Leon; Kalandadze, Manana; Tsintsadze, Nino; Machtei, Eli E.

2013-01-01

72

Periodontal status among adolescents in Georgia. A pathfinder study.  

PubMed

Objectives. The aim of the present pathfinder study was to screen and map the periodontal status of Georgian population in accordance with the guidelines of the World Health Organization for population based surveys. Methods. During 2012, a pathfinder study was conducted to collect this data. For the periodontal portion of the study, 15-year-old school children were examined in the capital city of Tbilisi as well as in two other large cities and 4 smaller villages. All participants were examined by a trained dental team in a classroom using a dental mirror and a periodontal probe. Periodontal examination included plaque scores, calculus scores, probing depth measurements and bleeding on probing. These measurements were recorded for the Ramfjord index teeth. Results. A total of 397 15-year-old participants were examined in this pathfinder study. There were 240 females (60.45%) and 157 males (39.55%). Of the total participants 196 (49.37%) were urban adolescents while 201 (50.63%) were from rural communities. Mean probing depth was 3.34 ± 0.57 mm with a range of 1 to 10 mm; a relatively high proportion (34.26%) of these subjects presented with at least one site with pockets of 5 mm or deeper. Males presented with greater plaque, calculus and probing depths than females. When urban and rural populations were compared, urban participants presented with more plaque, probing depths and bleeding on probing. Greater pocket depths were found to be related to the presence of plaque calculus and bleeding on probing. Conclusions. Overall, rather high incidences of periodontal pockets ? 5 mm were detected in this population. This data should serve to prepare further more detailed epidemiological studies that will serve to plan and implement prevent and treat strategies for periodontal diseases in Georgia and also help make manpower decisions. PMID:24109543

Levin, Liran; Margvelashvili, Vladimer; Bilder, Leon; Kalandadze, Manana; Tsintsadze, Nino; Machtei, Eli E

2013-09-17

73

Coral reef assessment: An index utilizing sediment constituents  

Microsoft Academic Search

Resource managers need inexpensive bioindicators to evaluate the health of coral reef ecosystems and to inform decisions on when and where to utilize more expensive assessment techniques. Following USEPA Guidelines for Evaluating Ecological Indicators, I developed the SEDCON Index (SI), a rapid-assessment protocol whichutilizes reef sediment composition to assess the integrity of coral-reef communities. Keyadvantages of this index are that

Camille A. Daniels

2005-01-01

74

Does access to the bluestreak cleaner wrasse Labroides dimidiatus affect indicators of stress and health in resident reef fishes in the Red Sea?  

PubMed

Interactions between the bluestreak cleaner wrasse Labroides dimidiatus and its client reef fish are a textbook example of interspecific mutualism. The fact that clients actively visit cleaners and invite inspection, together with evidence that cleaners eat many client ectoparasites per day, indeed strongly suggests a mutualistic relationship. What remains unknown is how parasite removal affects the physiology of clients and thereby their body condition, health, and immune function. Here we addressed these issues in a field study in Ras Mohammed National Park, Egypt. In our study area, small reef patches are inter-spaced with areas of sandy substrate, thereby preventing many species (i.e., residents, including cleaner wrasses) from travelling between the reef patches. This habitat structure leads to a mosaic of resident clients with and without access to bluestreak cleaner wrasses, further referred to as "cleaner access", on which we focused our study. We found that residents with cleaner access had higher body condition than residents without cleaner access. However, indicators of stress like variation in cortisol levels corrected for handling time and various immune parameters were apparently unaffected by cleaner access. In fact antibody responses were significantly higher in fishes without cleaner access. This suggests that cleaner access decreases the need for active immunity and that this releases resources that might be allocated to other functions such as somatic growth and reproduction. PMID:21087610

Ros, Albert F H; Lusa, Jeanne; Meyer, Meghann; Soares, Marta; Oliveira, Rui F; Brossard, Michel; Bshary, Redouan

2010-11-16

75

Mars Pathfinder, Science Results, Geology and Geomorphology  

NSDL National Science Digital Library

This NASA-hosted site is a section of the Mars Pathfinder Science Results Directory with a specific emphasis on the geologic and geomorphic characteristics observed. Many photos and satellite images are available, with the option to view and download full size images. Scientific theories are offered as to the probable geomorphic agents sculpting Mars' surface.

76

Pathfinders: An Intellectual Guide to Libraries.  

ERIC Educational Resources Information Center

Intended as an example for other college libraries, this collection of 38 pathfinders and bibliographies was developed by the reference staff of the Calvin Coolidge Library at Castleton State College, Vermont. Designed to present the types of literature available in particular subject fields and those works readily available in the Coolidge…

Jung, Claudia Ruediger; And Others

77

Pathfinders: An Intellectual Guide to Libraries.  

ERIC Educational Resources Information Center

|Intended as an example for other college libraries, this collection of 38 pathfinders and bibliographies was developed by the reference staff of the Calvin Coolidge Library at Castleton State College, Vermont. Designed to present the types of literature available in particular subject fields and those works readily available in the Coolidge…

Jung, Claudia Ruediger; And Others

78

Progress report on Mars Pathfinder Project approach  

Microsoft Academic Search

The Mars Pathfinder Project, one of NASA's first Discovery Class missions, will launch on December 2, 1996 and land on Mars on July 4, 1997 at low cost, fixed price, and on a short development schedule. This paper summarizes the mission, its science return and progress to date on its innovative \\

A. J. Spear

1996-01-01

79

Mars Pathfinder Project: Planetary Constants and Models  

Microsoft Academic Search

This document provides a common set of astrodynamic constants and planetary models for use by the Mars Pathfinder Project. It attempts to collect in a single reference all the quantities and models in use across the project during development and for mission operations. These models are central to the navigation and mission design functions, but they are also used in

Robin Vaughan

1995-01-01

80

Progress report on Mars Pathfinder Project approach  

Microsoft Academic Search

The Mars Pathfinder Project, one of NASA's first Discovery Class missions, will launch on December 2, 1996 and land on Mars on July 4, 1997 at low cost, fixed price, and on a short development schedule. This paper summarizes the mission, its science return and progress to date on its innovative “Cheaper, Better, Faster” project implementation approach

A. J. Spear

1996-01-01

81

Pathfinders on Black Dance in America.  

ERIC Educational Resources Information Center

This is a compilation of 18 pathfinders (i.e., a bibliographic instruction aid) on black dance in America, prepared by graduate students in the "Information Resources in the Humanities" and the "Information Resources in the Social Sciences" classes in the Graduate School of Library and Information Science at the University of Texas at Austin. The…

Roy, Loriene, Ed.

82

PATHFINDER ATOMIC POWER PLANT SHIELDING ANALYSIS  

Microsoft Academic Search

Shielding for the Pathfinder Atomic Power Plant, which incorporates a ; direct-cycle controlled-recirculation boiling-water reactor with an integral ; nuclear superheater, was designed. Information is presented on the shield ; design, dose levels for all areas of the plant, and methods of calculation. ; Major sources are the reactor complex in the reactor building, the main steam ; line, turbine,

R. J. Holl; D. W. Stephen

1962-01-01

83

PATHFINDER ATOMIC POWER PLANT RADIATION SHIELDING STUDY  

Microsoft Academic Search

Alternate concepts studied for the various shielding requirements in the ; Pathfinder Atomic Power Plant are described. It is concluded that a concrete ; shield surrounding the reactor pressure vessel is an adequate biological shield. ; This shield is made up of two parts: an outer two foot section which is both ; shield and structaral support for the various

R. Corcoran; H. C. Crumpacker; D. M. Leppke

1959-01-01

84

PATHFINDER ATOMIC POWER PLANT. REACTOR INTERNAL COMPONENTS  

Microsoft Academic Search

Major reactor internal components, test programs related to component ; development, and methods used in component design analysis for the Pathfinder ; Reactor are described. The components described include: boiler core grid plate, ; boiler core shroud, fuel element hold-down assembly, steam dryer assembly, steam ; separator support shelf, and nuclear superheater. (M.C.G.);

D. R. Bruesewitz; J. F. Wilson; E. C. rothen; D. J. Nolan; J. F. Patterson; S. P. Wnuk

1963-01-01

85

Effectiveness of benthic foraminiferal and coral assemblages as water quality indicators on inshore reefs of the Great Barrier Reef, Australia  

Microsoft Academic Search

Although the debate about coral reef decline focuses on global disturbances (e.g., increasing temperatures and acidification), local stressors (nutrient runoff and overfishing) continue to affect reef health and resilience. The effectiveness of foraminiferal\\u000a and hard-coral assemblages as indicators of changes in water quality was assessed on 27 inshore reefs along the Great Barrier\\u000a Reef. Environmental variables (i.e., several water quality

S. Uthicke; A. Thompson; B. Schaffelke

2010-01-01

86

Jurassic Reef Park  

NSDL National Science Digital Library

Dr. Reinhold Leinfelder of the University of Stuttgart, Germany created this interesting site in English and German, offering a "virtual trip to the reefs of the Jurassic Period." In the Introduction, viewers will find background material and comparisons of modern and ancient reefs. Further information is provided in the sections on reef architecture, reef formation, Jurassic reefs, and reefs and global climate change. Although the English language is slightly quirky, the content and images more than compensate, making this a worthwhile site.

87

The Magnetic Properties Experiments on Mars Pathfinder  

NASA Astrophysics Data System (ADS)

A remarkable result from the Viking missions was the discovery that the Martian soil is highly magnetic, in the sense that the soil is attracted by permanent magnets. Both the strong and weak magnets on the Viking landers were saturated with dust throughout the mission. Appropriate limits for the spontaneous magnetization sigma_S were advanced: 1 Am(2) (kg soil)(-1) < sigma_S < 7 Am(2) (kg soil)(-1) . The essential difference between the Magnet Arrays for Mars Pathfinder and the Viking Magnetic Properties Experiment is that Magnet Arrays on Pathfinder will include magnets of lower strengths that the weakest Viking magnet. The five magnets consist of small ring magnets concentric with oppositely polarized cylindrical magnets. The outer diameter of the ring magnets is 18 mm. Discrete (single phase) particles of strongly magnetic minerals (gamma -Fe2O3 or Fe3O4) will stick to all five magnets, while composite (multiphase) particles will stick preferentially to the strongest magnets. Two Magnet Arrays are placed on the Pathfinder lander, with a distance of 1180 and 1450 mm, respectively, from the Imager for Mars Pathfinder (IMP). The magnets will attract airborne dust, and the dust on the magnets will be periodically viewed by the IMP. The images transmitted to Earth are the data on which conclusions on the magnetic properties of the dust will be based. Besides the Magnet Arrays the Pathfinder lander carries two other types of magnets. The Tip Plate Magnet is placed at a distance of 10 cm from the IMP, and thus allows a rather high resolution imaging of the dust clinging to the magnet. The Ramp Magnets are placed near the end of the ramps by which the micro-rover will descend to the surface. The dust on the Ramp Magnets will be studied by the APX-spectrometer of the micro-rover.

Knudsen, J. M.; Gunnlaugsson, H. P.; Hviid, S. F.; Madsen, M. B.

1996-09-01

88

Coral reef bleaching: ecological perspectives  

NASA Astrophysics Data System (ADS)

Coral reef bleaching, the whitening of diverse invertebrate taxa, results from the loss of symbiotic zooxanthellae and/or a reduction in photosynthetic pigment concentrations in zooxanthellae residing within the gastrodermal tissues of host animals. Of particular concern are the consequences of bleaching of large numbers of reef-building scleractinian corals and hydrocorals. Published records of coral reef bleaching events from 1870 to the present suggest that the frequency (60 major events from 1979 to 1990), scale (co-occurrence in many coral reef regions and often over the bathymetric depth range of corals) and severity (>95% mortality in some areas) of recent bleaching disturbances are unprecedented in the scientific literature. The causes of small scale, isolated bleaching events can often be explained by particular stressors (e.g., temperature, salinity, light, sedimentation, aerial exposure and pollutants), but attempts to explain large scale bleaching events in terms of possible global change (e.g., greenhouse warming, increased UV radiation flux, deteriorating ecosystem health, or some combination of the above) have not been convincing. Attempts to relate the severity and extent of large scale coral reef bleaching events to particular causes have been hampered by a lack of (a) standardized methods to assess bleaching and (b) continuous, long-term data bases of environmental conditions over the periods of interest. An effort must be made to understand the impact of bleaching on the remainder of the reef community and the long-term effects on competition, predation, symbioses, bioerosion and substrate condition, all factors that can influence coral recruitment and reef recovery. If projected rates of sea warming are realized by mid to late AD 2000, i.e. a 2°C increase in high latitude coral seas, the upper thermal tolerance limits of many reef-building corals could be exceeded. Present evidence suggests that many corals would be unable to adapt physiologically or genetically to such marked and rapid temperature increases.

Glynn, P. W.

1993-03-01

89

Project O.R.B (Operation Reef Ball): Creating Artificial Reefs, Educating the Community  

NASA Astrophysics Data System (ADS)

The Project O.R.B. (Operation Reef Ball) team at South Plantation High School's Everglades Restoration & Environmental Science Magnet Program is trying to help our ailing south Florida coral reefs by constructing, deploying, and monitoring designed artificial reefs. Students partnered with the Reef Ball Foundation, local concrete companies, state parks, Girl Scouts, Sea Scouts, local universities and environmental agencies to construct concrete reef balls, each weighing approximately 500 lbs (227 kg). Students then deployed two artificial reefs consisting of over 30 concrete reef balls in two sites previously permitted for artificial reef deployment. One artificial reef was placed approximately 1.5 miles (2.4 km) offshore of Golden Beach in Miami-Dade County with the assistance of Florida Atlantic University and their research vessel. A twin reef was deployed at the mouth of the river in Oleta River State Park in Miami. Monitoring and maintenance of the sites is ongoing with semi-annual reports due to the Reef Ball Foundation and DERM (Department of Environmental Resource Management) of Miami-Dade County. A second goal of Project O.R.B. is aligned with the Florida Local Action Strategy, the Southeast Florida Coral Reef Initiative, and the U.S. Coral Reef Task Force, all of which point out the importance of awareness and education as key components to the health of our coral reefs. Project O.R.B. team members developed and published an activity book targeting elementary school students. Outreach events incorporate cascade learning where high school students teach elementary and middle school students about various aspects of coral reefs through interactive "edu-tainment" modules. Attendees learn about water sampling, salinity, beach erosion, surface runoff, water cycle, ocean zones, anatomy of coral, human impact on corals, and characteristics of a well-designed artificial reef. Middle school students snorkel on the artificial reef to witness first-hand the success of this artificial reef. Over 3,000 students have been reached through the educational outreach endeavors of Project O.R.B. This successful STEM project models the benefits of partnerships with universities, local K-12 public schools and community conservation organizations and provides students with authentic learning experiences. Students are able to have a positive impact on their local coral reef environment, their peers and their community through this comprehensive service-learning project.

Phipps, A.

2012-04-01

90

Web Reef Advisory System  

NSDL National Science Digital Library

The Web Reef Advisory System (WRAS) was developed by ReefBase and Reef Check, in collaboration with the Coastal Resources Center at the University of Rhode Island and the Department of Biological Sciences at the University of Southern California, as "an online application to input, view, and analyse Reef Check survey data. It calculates indicators of how good or bad a shape a particular reef is in, and what the underlying causes may be, based on Reef Check surveys." WRAS allows users to view, analyze, and add (registration required) data. Please note that site users must complete a free and brief registration process before they are granted full access to the Reef Check website. Other site offerings include an interactive Reef Check GIS feature (see website for browser requirements), and The Reef Check Barometer of Global Reef Condition which provides assessments of different regions based on Reef Check Indicators.

91

Assessment of Mars Pathfinder landing site predictions  

USGS Publications Warehouse

Remote sensing data at scales of kilometers and an Earth analog were used to accurately predict the characteristics of the Mars Pathfinder landing site at a scale of meters. The surface surrounding the Mars Pathfinder lander in Ares Vallis appears consistent with orbital interpretations, namely, that it would be a rocky plain composed of materials deposited by catastrophic floods. The surface and observed maximum clast size appears similar to predictions based on an analogous surface of the Ephrata Fan in the Channeled Scabland of Washington state. The elevation of the site measured by relatively small footprint delay-Doppler radar is within 100 m of that determined by two-way ranging and Doppler tracking of the spacecraft. The nearly equal elevations of the Mars Pathfinder and Viking Lander 1 sites allowed a prediction of the atmospheric conditions with altitude (pressure, temperature, and winds) that were well within the entry, descent, and landing design margins. High-resolution (~38 m/pixel) Viking Orbiter 1 images showed a sparsely cratered surface with small knobs with relatively low slopes, consistent with observations of these features from the lander. Measured rock abundance is within 10% of that expected from Viking orbiter thermal observations and models. The fractional area covered by large, potentially hazardous rocks observed is similar to that estimated from model rock distributions based on data from the Viking landing sites, Earth analog sites, and total rock abundance. The bulk and fine-component thermal inertias measured from orbit are similar to those calculated from the observed rock size-frequency distribution. A simple radar echo model based on the reflectivity of the soil (estimated from its bulk density), and the measured fraction of area covered by rocks was used to approximate the quasi-specular and diffuse components of the Earth-based radar echos. Color and albedo orbiter data were used to predict the relatively dust free or unweathered surface around the Pathfinder lander compared to the Viking landing sites. Comparisons with the experiences of selecting the Viking landing sites demonstrate the enormous benefit the Viking data and its analyses and models had on the successful predictions of the Pathfinder site. The Pathfinder experience demonstrates that, in certain locations, geologic processes observed in orbiter data can be used to infer surface characteristics where those processes dominate over other processes affecting the Martian surface layer. Copyright 1999 by the American Geophysical Union.

Golombek, M. P.; Moore, H. J.; Haldemann, A. F. C.; Parker, T. J.; Schofield, J. T.

1999-01-01

92

Vitality of reef coral populations off Key Largo, Florida: Recruitment and mortality  

Microsoft Academic Search

Recently, questions about the health of the coral reefs of the Florida Keys have been raised. Estimates of net recruitment\\u000a and mortality of reef corals on Carysfort Reef, Key Largo, Florida, suggest that these populations declined over the 14 month\\u000a interval studied. The greatest rate of change on Carysfort Reef, the most well developed reef in the northern Keys, occurred

Phillip Dustan; Coral Reef

1977-01-01

93

APECS - The Atacama Pathfinder Experiment Control System  

NASA Astrophysics Data System (ADS)

APECS is the CORBA based, distributed control system for the new Atacama Pathfinder EXperiment (APEX) Telescope located at the Llano de Chajnantor at an altitude of 5100m in the Atacama desert in northern Chile. The telescope has been operational since August 2005 and APECS is now being used for regular science observations. APECS employs a modern, object-oriented design. Generic interfaces facilitate adding new instruments. The IPython based observer command language allows using macros and creating more complex observing modes.

Muders, D.; Hafok, H.; Wyrowski, F.; Polehampton, E.; Belloche, A.; König, C.; Schaaf, R.

2006-07-01

94

Test-mass module for DECIGO Pathfinder  

Microsoft Academic Search

DECIGO Pathfinder (DPF) is the first precursory satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory), which is a future space gravitational wave antenna. The key instrument of DPF is a Fabry-Perot laser interferometer with freely floating test-masses, demonstrating precision laser interferometry, stabilized laser system and drag-free control system in orbit. A test-mass module is one of the sub-components of

Shuichi Sato; Yasuo Torii; Yaka Wakabayashi; Yumiko Ejiri; Rieko Suzuki; Akitoshi Ueda; Seiji Kawamura; Akito Araya; Masaki Ando; Yoshiyuki Obuchi; Norio Okada

2010-01-01

95

Reef Education Network  

NSDL National Science Digital Library

The University of Queensland's Reef Education Network (REN) is a wonderful introduction to the amazing world of coral reefs. REN has some cool images as well as information about reef research, current problems threatening coral reefs, and the many fascinating organisms that reside within a coral reef. The Life And Times section provides a nice overview of what a reef is, while the Ask A Brain Coral section gives some introduction to biotic and abiotic relationships that occur within reefs. A unique feature is the notebook, where students can record and organize information as they navigate throughout the site.

2001-01-01

96

Proceedings: Artificial Reef Conference. Artificial Reefs Around the World.  

National Technical Information Service (NTIS)

The section, Artificial Reefs Around the World, includes the following articles 'Artificial Reefs in France', 'Some Problems that may be Faced in the Construction of an Artificial Reef', 'Historical Review of Artificial Reef Activities in Japan', and 'A B...

W. H. Clark

1974-01-01

97

PATHFINDER ATOMIC POWER PLANT. BORON STAINLESS STEEL CONTROL RODS FOR PATHFINDER REACTOR. Final Summary Report  

Microsoft Academic Search

An extensive development, fabrication, and design analysis program was ; completed on 2 wt% boron stainiess steel for Pathfinder boiler and superheater ; control rods. Results indicated that the control rods will operate ; satisfactorily in the reactor under all foreseeable conditions. It was concluded ; that the maximum local burnup on the boiler rods is limited to 1.0 core

D. A. Patterson; D. A. Nehrig; R. H. Klumb; T. E. Peterson

1963-01-01

98

The role of SCUBA diver user fees as a source of sustainable funding for coral reef marine Protected areas  

Microsoft Academic Search

Coral reefs are both highly diverse and economically important. Human activities, however, threaten the world's coral reefs, endangering their biological and economic value. No take Marine Protected Areas (MPA), which ban fishing within MPA boundaries, help conserve and restore reef health and provide ecological resilience to reefs in the face of global warming and ocean acidification. In many cases, cost-benefit

Elizabeth Terk; Nancy Knowlton

2010-01-01

99

Analyzing Pathfinder data using virtual reality and superresolved imaging  

Microsoft Academic Search

The Mars Pathfinder mission used a unique capability to rapidly generate and interactively display three-dimensional (3-D) photorealistic virtual reality (VR) models of the Martian surface. An interactive terrain visualization system creates and renders digital terrain models produced from stereo images taken by the Imager for Mars Pathfinder (IMP) camera. The stereo pipeline, an automated machine vision algorithm, correlates features between

Carol R. Stoker; Eric Zbinden; Theodore T. Blackmon; Bob Kanefsky; Joel Hagen; Charles Neveu; Daryl Rasmussen; Kurt Schwehr; Michael Sims

1999-01-01

100

Pathfinders for Finding Information on Native Americans with Disabilities.  

ERIC Educational Resources Information Center

|This bibliography offers strategies for locating information on selected topics of concern to those working with Native Americans with disabilities. The strategies are arranged in a format called a pathfinder. Each pathfinder follows a similar format, beginning with a brief overview of the topic, followed with an annotated bibliography, and…

Roy, Loriene, Comp.

101

Immersive Environments for Mission Operations: Beyond Mars Pathfinder  

Microsoft Academic Search

Immersive environments are just beginning to be used to support mission operations at the Jet Propulsion Laboratory. This technology contributed to the Mars Pathfinder Mission in planning sorties for the Sojourner rover. Utilizing stereo imagery from the Imager for Mars Pathfinder (IMP) camera enabled the operator to visualize the terrain from the lander's point of view in 3D to assist

John Wright; Frank Hartman; Brian Cooper

102

Pathfinder: an online collaboration environment for citizen scientists  

Microsoft Academic Search

For over a century, citizen scientists have volunteered to collect huge quantities of data for professional scientists to analyze. We designed Pathfinder, an online environment that challenges this traditional division of labor by providing tools for citizen scientists to collaboratively discuss and analyze the data they collect. We evaluated Pathfinder in a sustainability and commuting context using a mixed methods

Kurt Luther; Scott Counts; Kristin B. Stecher; Aaron Hoff; Paul Johns

2009-01-01

103

Results from the Mars Pathfinder camera.  

PubMed

Images of the martian surface returned by the Imager for Mars Pathfinder (IMP) show a complex surface of ridges and troughs covered by rocks that have been transported and modified by fluvial, aeolian, and impact processes. Analysis of the spectral signatures in the scene (at 440- to 1000-nanometer wavelength) reveal three types of rock and four classes of soil. Upward-looking IMP images of the predawn sky show thin, bluish clouds that probably represent water ice forming on local atmospheric haze (opacity approximately 0.5). Haze particles are about 1 micrometer in radius and the water vapor column abundance is about 10 precipitable micrometers. PMID:9388170

Smith, P H; Bell, J F; Bridges, N T; Britt, D T; Gaddis, L; Greeley, R; Keller, H U; Herkenhoff, K E; Jaumann, R; Johnson, J R; Kirk, R L; Lemmon, M; Maki, J N; Malin, M C; Murchie, S L; Oberst, J; Parker, T J; Reid, R J; Sablotny, R; Soderblom, L A; Stoker, C; Sullivan, R; Thomas, N; Tomasko, M G; Wegryn, E

1997-12-01

104

Journey to the Reef  

NSDL National Science Digital Library

Despite their experiences with a cartoon sponge, most elementary students know little about the diverse inhabitants of coral reefs. Therefore, with vivid photography and video, diverse coral reef inhabitants were brought to life for the author's fifth-gra

Bryson, Linda

2010-01-01

105

Mars Pathfinder flight system integration and test.  

NASA Astrophysics Data System (ADS)

This paper describes the system integration and test experiences, problems and lessons learned during the assembly, test and launch operations (ATLO) phase of the Mars Pathfinder flight system scheduled to land on the surface of Mars on July 4, 1997. The Mars Pathfinder spacecraft consists of three spacecraft systems: cruise stage, entry vehicle and lander. The cruise stage carries the entry and lander vehicles to Mars and is jettisoned prior to entry. The entry vehicle, including aeroshell, parachute and deceleration rockets, protects the lander during the direct entry and reduces its velocity from 7.6 to 0 km/s in stages during the 5 min entry sequence. The lander's touchdown is softened by airbags which are retracted once stopped on the surface. The lander then uprights itself, opens up fully and begins surface operations including deploying its camera and rover. This paper overviews the system design and the results of the system integration and test activities, including the entry, descent and landing subsystem elements. System test experiences including science instruments, the microrover, Sojourner, and software are discussed. The final qualification of the entry, descent and landing subsystems during this period is also discussed.

Muirhead, B. K.

106

Journey to the Reef  

ERIC Educational Resources Information Center

|Despite their experiences with a cartoon sponge, most elementary students know little about the diverse inhabitants of coral reefs. Therefore, with vivid photography and video, diverse coral reef inhabitants were brought to life for the author's fifth-grade students. Students shared their knowledge in language arts and even explored coral reefs

Bryson, Linda

2010-01-01

107

Subsurface Onondaga reefs  

Microsoft Academic Search

Seven subsurface Onondaga reefs have been found in southwestern New York (6) and northwestern Pennsylvania (1). These reefs have had a maximum thickness of about 200 feet and cover an area of a few hundred acres. They are similar to nearly 30 smaller reefs in the same geologic section which have previously been found along the Onodaga outcrop. The discovery

Van Tyne

1995-01-01

108

Great Barrier Reef  

NSDL National Science Digital Library

This Landsat-7 color composite image shows a section of the famous Great Barrier Reef, the world's largest living organism. This view displays the southern end of the reef where it is composed of smaller, individual reef structures as opposed to a continuous bank as in the north.

Nasa; Day, Earth S.

109

Planetary Coral Reef Foundation  

NSDL National Science Digital Library

The Planetary Coral Reef Foundation was founded in 1991 to address the growing crisis of destruction of coral reefs. Topics include the PCRF's mission, its research activities at sea and in space, wastewater recycling, conservation tips that can help preserve reefs, and the organization's ship, R.V. Heraclitus.

110

PATHFINDER ATOMIC POWER PLANT. HYDRAULIC ANALYSIS OF PATHFINDER BOILE. Summary Report  

Microsoft Academic Search

A hydraulic analysis of the Pathfinder boiler core was completed. A ;\\u000a description of flow paths including a schematic diagram is included. Pressure ;\\u000a drops along primary and leakage fiow paths were calculatsd. After the resistance ;\\u000a of each of the leakage paths was identified and the available driving forces in ;\\u000a terms of pressure drops associated with the active

Sher

1961-01-01

111

Statistical Analysis of LISA Pathfinder Noise  

NASA Astrophysics Data System (ADS)

LISA Pathfinder (LPF) is an European Space Agency mission aiming to create the quietest environment for free-falling test masses in order to pave the way to the forthcoming space-based gravitational wave detectors. Reaching such an ambitious target will require a significant amount of system optimisation and characterisation, which will in turn require accurate and quantitative noise analysis procedures. In this paper we present a statistical procedure for the analysis of the noise in spectral domain that is based on the Kolmogorov-Smirnov test. The application on LPF synthetic data reveals the versatility of the Kolmogorov-Smirnov approach, which can easily cope with the correlations introduced by the Welch's overlapped segment averaging method for the calculation of the sample spectrum.

Ferraioli, L.

2013-01-01

112

Modal analysis of PATHFINDER unmanned air vehicle  

SciTech Connect

An experimental modal analysis was performed on PATHFINDER, a 450-lb, 100-ft wing span, flying-wing-design aircraft powered by solar/electric motors. The aircraft was softly suspended and then excited using random input from a long-stroke shaker. Modal data was taken from 92 measurement locations on the aircraft using newly designed, lightweight, tri-axial accelerometers. A conventional PC-based data acquisition system provided data handling. Modal parameters were calculated, and animated mode shapes were produced using SMS STARStruct{trademark} Modal Analysis System software. The modal parameters will be used for validation of finite element models, optimum placement of onboard accelerometers during flight testing, and vibration isolation design of sensor platforms.

Woehrle, T.G.; Costerus, B.W.; Lee, C.L.

1994-10-19

113

Mars Pathfinder/Global Surveyor Picturebook  

NSDL National Science Digital Library

Mars Pathfinder/Global Surveyor Picturebook is a Windows to the Universe Exploratour and provides information and images about the Martian landscape, the Rover, soils of Mars, dunes and wind, rocks, pebbles, clouds, sunsets, people involved with the Mission, and Martian geology. Windows to the Universe is a user-friendly learning system pertaining to the Earth and Space sciences. The objective of this project is to develop an innovative and engaging web site that spans the Earth and Space sciences and includes a rich array of documents, including images, movies, animations, and data sets that explore the Earth and Space sciences and the historical and cultural ties between science, exploration and the human experience. Links at the top of each page allow users to navigate between beginner, intermediate, and advanced options for each topic level.

Johnson, Roberta

2000-07-01

114

The magnetic properties experiments on Mars Pathfinder  

NASA Astrophysics Data System (ADS)

The Mars Pathfinder lander carried two magnet arrays, each containing five small permanent magnets of varying strength. The magnet arrays were passively exposed to the wind borne dust on Mars. By the end of the Mars Pathfinder mission a bull's-eye pattern was visible on the four strongest magnets of the arrays showing the presence of magnetic dust particles. From the images we conclude that the dust suspended in the atmosphere is not solely single phase particles of hematite (?-Fe2O3) and that single phase particles of the ferrimagnetic minerals maghemite (?-Fe2O3) or magnetite (Fe3O4) are not present as free particles in any appreciable amount. The material on the strongest magnets seems to be indistinguishable from the bright surface material around the lander. From X-ray fluorescence it is known that the soil consists mainly of silicates. The element iron constitutes about 13% of the soil. The particles in the airborne dust seem to be composite, containing a few percent of a strongly magnetic component. We conclude that the magnetic phase present in the airborne dust particles is most likely maghemite. The particles thus appear to consist of silicate aggregates stained or cemented by ferric oxides, some of the stain and cement being maghemite. These results imply that Fe2+ ions were leached from the bedrock, and after passing through a state as free Fe2+ ions in liquid water, the Fe2+ was oxidized to Fe3+ and then precipitated. It cannot, however, be ruled out that the magnetic particles are titanomagnetite (or titanomaghemite) occurring in palagonite, having been inherited directly from the bedrock.

Madsen, M. B.; Hviid, S. F.; Gunnlaugsson, H. P.; Knudsen, J. M.; Goetz, W.; Pedersen, C. T.; Dinesen, A. R.; Mogensen, C. T.; Olsen, M.; Hargraves, R. B.

1999-04-01

115

Factors Affecting the Distribution and Health of the Intertidal Coral Goniastrea aspera on the Reef Flat in Geoffrey Bay, Magnetic Island  

Microsoft Academic Search

The intertidal zone can be a harsh environment, presenting many challenges to the organisms inhabiting it. Given its dynamic nature, it is surprising that it is sometimes able to sustain systems as delicate and sensitive as coral reefs. Many organisms have adapted to life on the intertidal reef flat, and one of the most prominent on the northeastern coast of

Julia Smith

2006-01-01

116

Artificial Coral Reefs  

NSDL National Science Digital Library

Coral reefs are among the most diverse ecosystems on the planet...and the most threatened. Artificial reefs may help stem the loss of these valuable and beautiful habitats, with shipwrecks, old subway cars, and other structures taking the place of living coral or rocky outcrops. The following Web sites introduce artificial reefs, reef ecology, and some ongoing efforts to establish reef communities in the U.S. and beyond. PBS's NATURE offers a fascinating look at the artificial reefs created by the thousands of shipwrecks and downed planes from World War II that riddle the South Pacific (1). This is the companion Web site to the documentary War Wrecks of the Coral Seas, and it includes some great multimedia features. The next site comes from the National Oceanic and Atmospheric Administration and contains an excellent photo gallery of coral ecosystems around the world (2). The collection includes six pages of artificial reef photos taken in the Pacific. The following site comes from the online companion to the BBC's acclaimed documentary series The Blue Planet. Based on the episode The Web of Life, this site offers a fun, multimedia challenge for learning about and testing one's knowledge of coral reefs (3). The site includes a section on artificial reefs (click on Take it Further). Next, an August 2001 segment from National Public Radio's All Things Considered explores efforts to create artificial reefs using decommissioned New York City subway cars -- a project of Delaware's Department of Natural Resources and Environmental Control in the Division of Fish and Wildlife (4). Likewise, the non-profit group Artificial Reefs of the Keys is working to bring a de-commissioned military ship to the Florida Keys (5). The New Jersey Scuba Diver Web site provides an excellent introduction to artificial reef ecology; focused on reefs in New Jersey, of course. The mini-tutorial comes courtesy of William Figly, Principal Fisheries Biologist for the New Jersey Artificial Reef Program (6). The Fall 2001 issue of California Wild, the magazine of the California Academy of Sciences, addresses the benefits and concerns of off shore oil rigs becoming artificial reefs (7). Finally, visitors will find dozens of news articles and Web links related to artificial reefs in this entry, a page from the New England Artificial Reef Society Web site (8).

Sohmer, Rachel.

117

Ocean World: Coral Reefs  

NSDL National Science Digital Library

Texas A&M University presents Ocean World, a Web-based educational resource for oceanography. The feature on coral reefs has the most direct life sciences application, with easy-to-navigate sections about the coral animal, coral reefs as the rainforests of the sea, symbiosis, ecosystem services, and coral reef threats and conservation. The Web site also includes a handy hypertext glossary, an interactive quiz, and annotated links to interesting Web sites, including sites that provide real-time reef images and data. While no formal lesson plans are provided, this Web site could be easily incorporated to a related classroom module for a range of grade levels.

2007-11-20

118

Caribbean-wide decline in carbonate production threatens coral reef growth  

PubMed Central

Global-scale deteriorations in coral reef health have caused major shifts in species composition. One projected consequence is a lowering of reef carbonate production rates, potentially impairing reef growth, compromising ecosystem functionality and ultimately leading to net reef erosion. Here, using measures of gross and net carbonate production and erosion from 19 Caribbean reefs, we show that contemporary carbonate production rates are now substantially below historical (mid- to late-Holocene) values. On average, current production rates are reduced by at least 50%, and 37% of surveyed sites were net erosional. Calculated accretion rates (mm?year?1) for shallow fore-reef habitats are also close to an order of magnitude lower than Holocene averages. A live coral cover threshold of ~10% appears critical to maintaining positive production states. Below this ecological threshold carbonate budgets typically become net negative and threaten reef accretion. Collectively, these data suggest that recent ecological declines are now suppressing Caribbean reef growth potential.

Perry, Chris T.; Murphy, Gary N.; Kench, Paul S.; Smithers, Scott G.; Edinger, Evan N.; Steneck, Robert S.; Mumby, Peter J.

2013-01-01

119

Caribbean-wide decline in carbonate production threatens coral reef growth.  

PubMed

Global-scale deteriorations in coral reef health have caused major shifts in species composition. One projected consequence is a lowering of reef carbonate production rates, potentially impairing reef growth, compromising ecosystem functionality and ultimately leading to net reef erosion. Here, using measures of gross and net carbonate production and erosion from 19 Caribbean reefs, we show that contemporary carbonate production rates are now substantially below historical (mid- to late-Holocene) values. On average, current production rates are reduced by at least 50%, and 37% of surveyed sites were net erosional. Calculated accretion rates (mm?year(-1)) for shallow fore-reef habitats are also close to an order of magnitude lower than Holocene averages. A live coral cover threshold of ~10% appears critical to maintaining positive production states. Below this ecological threshold carbonate budgets typically become net negative and threaten reef accretion. Collectively, these data suggest that recent ecological declines are now suppressing Caribbean reef growth potential. PMID:23360993

Perry, Chris T; Murphy, Gary N; Kench, Paul S; Smithers, Scott G; Edinger, Evan N; Steneck, Robert S; Mumby, Peter J

2013-01-01

120

Constellation Pathfinder: A University Nanosatellite Project  

NASA Astrophysics Data System (ADS)

Under the task of nanosatellite mission design, we developed a mission concept that enables hundreds of one-kilogram spacecraft to be placed into orbit with a single mothership. We performed trade studies to arrive at a positive feasibility assessment. The results of that study were described in two publications. Second, under the task of spacecraft design, we developed nanosatellite designs needed to enable constellation missions. Design studies were conducted and subsystems prototyped, including a spin-table and launcher concept for a small stack of nanosatellites. Engineering design studies of this work appeared in the refereed literature. Instruments to be flown on such a small craft have been specified and then developed as part of a related AF SBIR effort. Undergraduate students (>100 in the Aerospace Engineering, Mechanical Engineering, and Electrical and Computer Engineering departments) played an enormous role in the mission and spacecraft definitions of the Constellation Pathfinder project. In addition to five publications, numerous invited and contributed presentations of these studies have been presented at national and international meetings.

Spence, Harlan E.; Petschek, Harry E.

2002-08-01

121

NASA's Earth System Science Pathfinder Program  

NASA Astrophysics Data System (ADS)

NASA's Earth Science Enterprise has the lead role in fulfilling the first element of the Agency's three-part mission statement, "To Understand and Protect Our Home Planet". We accomplish this by developing a scientific understanding of the Earth system and its response to natural and human-induced changes to enable improved prediction of climate, weather, and natural hazards. NASA brings to global change research the ability to view the Earth from space, as well as the capability to define and manage and end-to-end program of research to answer large scale Earth science questions. Our view from space allows us to view local and regional changes in their global context. The Earth Observing System of satellites begins monitoring variability and trends in global change parameters of known importance. Complimenting EOS, NASA' Earth System Science Pathfinder satellites explore Earth system processes that have yet to be measured globally. These processes, such as aerosol properties and vertical distribution and carbon sources and sinks, represent areas of great uncertainty in climate change. They also tend to require advanced remote sensing technologies, such as radars, lidars, and advanced spectrometers. NASA's ESSP program solicits the latest and best ideas from the science community to meet these challenges. NASA coordinates its plans with its international space partners to assure our collective space programs effectively and efficiently meet the requirements of internationally important global change research programs.

Asrar, G. R.

2003-04-01

122

Subsurface Onondaga reefs  

SciTech Connect

Seven subsurface Onondaga reefs have been found in southwestern New York (6) and northwestern Pennsylvania (1). These reefs have had a maximum thickness of about 200 feet and cover an area of a few hundred acres. They are similar to nearly 30 smaller reefs in the same geologic section which have previously been found along the Onodaga outcrop. The discovery well for Onodaga reef gas, although not recognized as such at the time, was the No. 1 Quinlan Oil. The well was drilled in 1933 in the Town of Olean, Cattaraugus County, New York near the New York-Pennsylvania State line. The first of the more recent Onondaga reef discoveries occurred in 1967 at Wyckoff in the Town of Jasper, Steuben County, New York. This discovery touched off a leasing and seismic exploration boom in this area of New York. As a result of these studies, two more reefs were discovered in 1971, two in 1974 and the last so far in 1981. These seven reefs have produced 7.1 billion cubic feet of gas. The smallest, Flatstone, has production to data of about 700 million cubic feet. The Onondaga reefs are of basal Onondaga, or Edgecliff, age. The Edgecliff is a light gray, coarsely crystalline, biostromal limestone. Onondaga reefs may have begun forming on somewhat higher parts of the sea floor in crinoid thickets. Because the Onondaga is considerably thicker in that area these so-called {open_quotes}reefs{close_quotes} are buried entirely within the total Onondaga section. They have been called reefs mainly because gas shows have been encountered in the lower Onondaga when it was drilled through by wells aiming for deeper Medina sandstones gas production. Nevertheless, gas production from them has been minimal. The seal consists of surrounding and overlapping black and gray middle Devonian Hamilton shales. The basal portions are surrounded by onlapping upper Onondaga limestones. The source of the gas is believed to be the highly organic Hamilton shale.

Van Tyne, A.M. [Van Tyne Consulting, Wellsville, NY (United States)

1995-09-01

123

Coral reefs at risk  

NASA Astrophysics Data System (ADS)

Eighty-eight percent of Southeast Asia's reefs are threatened by overfishing, destructive fishing, and sedimentation and pollution from inland activities, according to a new report by 35 regional scientists published by the World Resources Institute.Nearly 100,000 square kilometers of coral reefs—34% of the world's total—are located in Southeast Asia.

Showstack, Randy

124

Use of a pathfinder optical telescope element for James Webb Space Telescope risk mitigation  

NASA Astrophysics Data System (ADS)

A Pathfinder of the James Webb Space Telescope (JWST) Optical Telescope Element is being developed to check out critical ground support equipment and to rehearse integration and testing procedures. This paper provides a summary of the baseline Pathfinder configuration and architecture, objectives of this effort, limitations of Pathfinder, status of its development, and future plans. Special attention is paid to risks that will be mitigated by Pathfinder.

Feinberg, Lee D.; Keski-Kuha, Ritva; Atkinson, Charlie; Texter, Scott C.

2010-07-01

125

Low cost approach to Mars Pathfinder and small landers.  

NASA Astrophysics Data System (ADS)

NASA's Mars Surveyor Program will launch small orbiters to Mars, each carrying subsets of the Mars Observer instruments. Mars Pathfinder, launching in Dec 1996 and landing Jul 4, 1997, will demo a low cost delivery system to the surface of Mars for follow-on Mars Surveyor and Discovery Program landers. The major objective of Pathfinder, acquisition and return of engineering data on EDL and lander performance, will be completed within the first few hours after landing. Next, a rover will be deployed. The primary mission durations for the rover and lander are one week and one month, respectively. However, there is nothing to preclude their operations past the primary mission durations. While Pathfinder is an engineering demo, it accomplishes a focused, exciting set of science investigations with a stereo, multi-color lander imager; atmospheric instrumentation, used as a weather station after landing; the APX; and the rover including its aft and forward cameras.

Spear, A. J.

126

Thresholds and the resilience of Caribbean coral reefs.  

PubMed

The deteriorating health of the world's coral reefs threatens global biodiversity, ecosystem function, and the livelihoods of millions of people living in tropical coastal regions. Reefs in the Caribbean are among the most heavily affected, having experienced mass disease-induced mortality of the herbivorous urchin Diadema antillarum in 1983 and two framework-building species of coral. Declining reef health is characterized by increases in macroalgae. A critical question is whether the observed macroalgal bloom on Caribbean reefs is easily reversible. To answer this question, we must resolve whether algal-dominated reefs are an alternative stable state of the ecosystem or simply the readily reversible result of a phase change along a gradient of some environmental or ecological parameter. Here, using a fully parameterized simulation model in combination with a simple analytical model, we show that Caribbean reefs became susceptible to alternative stable states once the urchin mortality event of 1983 confined the majority of grazing to parrotfishes. We reveal dramatic hysteresis in a natural system and define critical thresholds of grazing and coral cover beyond which resilience is lost. Most grazing thresholds lie near the upper level observed for parrotfishes in nature, suggesting that reefs are highly sensitive to parrotfish exploitation. Ecosystem thresholds can be combined with stochastic models of disturbance to identify targets for the restoration of ecosystem processes. We illustrate this principle by estimating the relationship between current reef state (coral cover and grazing) and the probability that the reef will withstand moderate hurricane intensity for two decades without becoming entrained in a shift towards a stable macroalgal-dominated state. Such targets may help reef managers face the challenge of addressing global disturbance at local scales. PMID:17972885

Mumby, Peter J; Hastings, Alan; Edwards, Helen J

2007-11-01

127

New protection initiatives announced for coral reefs  

NASA Astrophysics Data System (ADS)

Off the coasts of some of the South Pacific's most idyllic-sounding atolls, Austin Bowden-Kerby has seen first-hand the heavy damage to coral reefs from dynamite and cyanide fishing. For instance, while snorkeling near Chuuk, an island in Micronesia, he has observed craters and rubble beds of coral, which locals have told him date to World War II ordnance.A marine biologist and project scientist for the Coral Gardens Initiative of the Foundation for the Peoples of the South Pacific, Bowden-Kerby has also identified what he says are some public health effects related to destroyed coral reefs and their dying fisheries. These problems include protein and vitamin A deficiency and blindness, all of which may—in some instances—be linked to poor nutrition resulting from lower reef fish consumption by islanders, according to Bowden-Kerby.

Showstack, Randy

128

Life on the Reef  

NSDL National Science Digital Library

This Discovery Channel feature is a live expedition with the American Museum of Natural History. Marine biologists studying the barrier reefs in the Bahamas provide information on scavenger sea worms, brain coral, shell-less nudibranches, sea turtles and sharks, and many other ocean creatures. The scientists also track the various species of the reef using NASA images from space. Photographs and descriptions of the animals and plants off Andros Island are categorized into lagoon, reef, and shelf organisms. Descriptions of the marine biologists working in the Bahamas, and their research interests are provided.

129

The CLOUDSAT Experiment: A NASA Pathfinder Mission  

NASA Astrophysics Data System (ADS)

CloudSat will be the first spaceborne deployment of a 94-GHz cloud profiling radar. The mission is a partnership between NASA, Colorado State University, the Canadian Space Agency (CSA), the US Air Force (USAF), and the US Department of Energy's Atmospheric Radiation Measurements (ARM) Program. The spacecraft will be launched in 2004 and will fly in on-orbit formation with the CALIPSO spacecraft and the EOS-Aqua spacecraft, providing a suite of measurements for cloud and aerosol studies. The CloudSat experiment promotes the optimal use of multi-sensor data to produce new pathfinding knowledge that will advance our understanding of the participation of clouds and the hydrological cycle in the Earth climate system. The vertical profile of cloud properties provided by CloudSat fills a critical gap in the investigation of feedback mechanisms linking clouds to climate. Measuring the vertical profile of cloud properties is best addressed by a combination of active and passive instruments, and this will be achieved by combining the radar data of CloudSat with active and passive data from other sensors of the constellation. CloudSat will also provide the first real estimate of the mass of water and ice in the atmosphere and the proportion of this water and ice that falls as precipitation. The CloudSat Science Team is an international partnership, with members from USA, Canada, Japan and Europe having expertise in cloud radar design and observations, cloud and radiation research, and NWP, GCM and cloud modeling. Validation will rely heavily on the systematic measurement programs of ARM as well as systematic measurements planned for selected sites in Europe and Japan. Validation will also benefit from the aircraft radar measurement activities of USA, Canada, Japan and Europe, from the measurement capabilities at number of universities, and from cloud field-campaign activities representing targets of opportunity planned in the coming years, including field campaigns associated with the CALIPSO and AQUA missions. Further information on the CloudSat mission may be obtained from the author or by accessing the CloudSat Home Page at http://cloudsat.atmos.colostate.edu.

Stephens, G.; Vane, D.

2003-04-01

130

Martian Mixed Layer during Pathfinder Mission  

NASA Astrophysics Data System (ADS)

In situ measurements of the Martian Planetary Boundary Layer (MPBL) encompass only the sur- face layer. Therefore, in order to fully address the MPBL, it becomes necessary to simulate somehow the behaviour of the martian mixed layer. The small-scale processes that happen in the MPBL cause GCM's ([1], [2]) to describe only partially the turbulent statistics, height, convective scales, etc, of the surface layer and the mixed layer. For this reason, 2D and 3D martian mesoscale models ([4], [5]), and large eddy simulations ([4], [6], [7], [8]) have been designed in the last years. Although they are expected to simulate more accurately the MPBL, they take an extremely expensive compu- tational time. Alternatively, we have derived the main turbu- lent characteristics of the martian mixed layer by using surface layer and mixed layer similarity ([9], [10]). From in situ temperature and wind speed measurements, together with quality-tested simu- lated ground temperature [11], we have character- ized the martian mixed layer during the convective hours of Pathfinder mission Sol 25. Mean mixed layer turbulent statistics like tem- perature variance < ?? >, horizontal wind speed variance < ?u,v >, vertical wind speed variance < ?w >, viscous dissipation rate < ? >, and turbu- lent kinetic energy < e > have been calculated, as well as the mixed layer height zi, and the convective scales of wind w? and temperature ??. Our values, obtained with negligible time cost, match quite well with some previously obtained results via LES's ([4] and [8]). A comparisson between the above obtained mar- tian values and the typical Earth values are shown in Table 1. Convective velocity scale w doubles its counterpart terrestrial typical value, as it does the mean wind speed variances < ?u,v > and < ?w >. On the other hand, the temperature scale ?? and the mean temperature variance < ? > are virtually around one order higher on Mars. The limitations of these results concern the va- lidity of the convective mixed layer similarity. This theory neglects the effect of the radiation heating which is negligible under fair weather conditions on Earth. However, it is relevant under martian conditions due to the absorption of solar radiation by dust. Supported both by [11] and the low dust optical depth (? 0.3 for the PF summer), the con- vective heating of the mixed layer domiantes the radiation heating (around three times higher), al- lowing us to estimate these values via mixed layer similarity.

Martinez, G. M.; Valero, F.; Vazquez, L.

2008-09-01

131

Future launcher demonstrator. Challenge and pathfinder  

NASA Astrophysics Data System (ADS)

For future and advanced launch vehicles emphasis is focused on single-stage-to-orbit (SSTO) concepts and on completely reusable versions with the goal to reduce the recurrent launch cost, to improve the mission success probability and also safety for the space transportation of economically attractive payloads into Low Earth Orbit. Both issues, the SSTO launcher and the low cost reusability are extremely challenging and cannot be proven by studies and on-ground tests alone. In-flight demonstration tests are required to verify the assumptions and the new technologies, and to justify the new launcher-and operations-concepts. Because a number of SSTO launch vehicles are currently under discussion in terms of configurations and concepts such as winged vehicles for vertical or horizontal launch and landing (from ground or a flying platform), or wingless vehicles for vertical take-off and landing, and also in terms of propulsion (pure rockets or a combination of air breathing and rocket engines), an experimental demonstrator vehicle appears necessary in order to serve as a pathfinder in this area of multiple challenges. A suborbital Reusable Rocket Launcher Demonstrator (RRLD) has been studied recently by a European industrial team for ESA. This is a multipurpose, evolutionary demonstrator, conceived around a modular approach of incremental improvements of subsystems and materials, to achieve a better propellant mass fraction i.e. a better performance, and specifically for the accomplishment of an incremental flight test programme. While the RRLD basic test programme will acquire knowledge about hypersonic flight, re-entry and landing of a cryogenic rocket propelled launcher — and the low cost reusability (short turnaround on ground) in the utilization programme beyond basic testing, the RRLD will serve as a test bed for generic testing of technologies required for the realization of an SSTO launcher. This paper will present the results of the European RRLD study which proposes a winged suborbital rocket launcher operations & technology demonstrator for vertical take-off and horizontal landing — using primarily conventional technology and materials as a first step towards the challenging goal of a reusable SSTO ETO launch vehicle.

Kleinau, W.; Guerra, L.; Parkinson, R. C.; Lieberherr, J. F.

1996-02-01

132

A Pathfinder for Animal Research and Animal Rights.  

ERIC Educational Resources Information Center

|This pathfinder was originally prepared for "Biomedical Research and Animal Rights," a session sponsored by the Veterinary Medical Libraries and Research Libraries Sections of the Medical Library Association. Current resources are described, from bibliographies to electronic bulletin boards, which relate to the issue of laboratory animal welfare…

Anderson, David C.

1992-01-01

133

Torsion pendulum testing of the LISA Pathfinder Gravitational Reference Sensor  

Microsoft Academic Search

We present results of testing of the LISA pathfinder gravitational reference sensor (GRS) using the torsion pendulum facitlity at the University of Trento. We investigate the surface force disturbances arising from of the GRS and the sensor stiffness, or coupling between the sensor and test mass motion. We also investigate specific sources of noise, including DC bias variations in the

Peter Wass; Stefano Vitale; Bill Weber; Rita Dolesi; Giacomo Ciani; David Tombolato; Antonella Cavalleri; Daniele Nicolodi; Mauro Hueller

2008-01-01

134

Visualizing Evolving Networks: Minimum Spanning Trees versus Pathfinder Networks  

Microsoft Academic Search

Network evolution is a ubiquitous phenomenon in a wide variety of complex systems. In fields such as statistical mechanics, there has been increasingly widespread interest in modeling the growth of complex networks. In this article, we compare two network visualization techniques, minimum spanning trees (MSTs) and Pathfinder networks (PFNETs), and their visualizations of co - citation networks of scientific publications.

Chaomei Chen; Steven Morris

2003-01-01

135

MARS PATHFINDER CRUISE STAGE\\/ ENTRY VEHICLE SEPARATION DYNAMICS  

Microsoft Academic Search

I'rior to atmospheric entry, Mars Pathfinder flight system will separate its entry vehicle from its cruise stage, and establish the entry conditions for a passive and unconventional entry, descent, and landing approach. This paper summarizes a separation dynamics analysis conducted to demonstrate that the cruise separation system design is viable and ensure that adequate design marginss exist with the effects

Chia-Yen Peng; Kemeth S. Smith

1996-01-01

136

Mars Pathfinder Mission Internet-Based Operations Using WITS  

Microsoft Academic Search

The Web Interface for Telescience (WITS) is an Internet-based tool that the Mars Pathfinder mission used for both mission operations at JPL and public outreach. WITS enables the viewing of downlinked im- ages and results in various ways, terrain feature mea- surement and annotation, and planning of daily mis- sion activities. WITS is written in the Java language and is

Paul G. Backes; Kam S. Tso; Gregory K. Tharp

1998-01-01

137

PATHFINDER ATOMIC POWER PLANT. BUTTERFLY VALVE CAVITATION TEST  

Microsoft Academic Search

Tests were made on butterfly vaives similar to those used in the ; discharge leg of each of the three external recirculation loops of the Pathfinder ; reactor in order to determine the critical values of a dimensionless cavitation ; number ( \\/occurred in pu ) used to specify the limits of operation for reactor ; valves, at incipient cavitation.

1963-01-01

138

PROTOTYPE RECIRCULATION PUMP TESTS. PATHFINDER ATOMIC POWER PLANT SUMMARY REPORT  

Microsoft Academic Search

Results of tests performed on the Pathfinder Atomic Power Plant ; recirculation prototype pump and its components are presented. Tests included a ; preliminary seal test, a serrated bushing test, a cold performance test, and a ; hot loop test. Results indicated thut the pump should give trouble-free service ; in the field if operated as intended and within the

R. Haugen; D. J. Nolan

1961-01-01

139

PATHFINDER ATOMIC POWER PLANT DETAILED FLUX MEASUREMENTS IN SUPERHEATER CELLS  

Microsoft Academic Search

Experiments were conducted in the Allis-Chalmers Critical Experimental ; Facility to determine the regionaverage thermal flux and flux shape in a unit ; Pathfinder superheater cell. Accuiate values are necessary in order to calculate ; superheater constants. Measurements were made using Cu-Mn wires (radial traverse ; for regionaverage) and Al-U foils (sectioned for region-average) and foilettes ; (for flux detail).

H. F. Finn; R. H. Vollmer

1962-01-01

140

PATHFINDER ATOMIC POWER PLANT COOLANT DISTRIBUTION TESTS. Final Report  

Microsoft Academic Search

Tests were made to determine the head loss coefficient through the inlet ; plenum of the Pathfinder reactor and to determine the now distribution among the ; fuel element nozzles for various operating conditions--with all three pumps ; operating at the same flow rate and with any combination of only two pumps ; operating at the same flow rate. A

J. Wilson; R. Styles

1959-01-01

141

Teacher job satisfaction: lessons from the TSW Pathfinder Project  

Microsoft Academic Search

Government policy assumes that modernization and remodelling will be effective as external intervention mechanisms to improve job satisfaction. Based on data collected as part of the evaluation of the ‘Transforming the School Workforce Pathfinder Project’, an argument is presented here which suggests that internal management models may be more effective in improving teacher job satisfaction. By comparing the responses of

Graham Butt; Ann Lance; Antony Fielding; Helen Gunter; Steve Rayner; Hywel Thomas

2005-01-01

142

Coral reefs in crisis.  

PubMed

This article reports on the crisis facing reefs throughout the world and the struggle to save them. Coral reefs, one of the biological wonders of the world, are among the largest and oldest living communities of plants and animals on earth, having been evolved between 200 and 450 million years ago. Located mostly in the Pacific region, most established coral reefs are now dead and only the upper layer is covered by a thin changeable skin of living coral. Reefs, over the years, have been the main source of animal protein for over 1 billion people in Asia. Countries near the coastlines, which relied on the seas, have resorted to dynamite fishing, poisoning and other illegal and dangerous techniques. Overpopulation and pollution has caused the deteriorating conditions of the 600,000 sq. km of coral reefs worldwide. Despite these conditions, the government has ignored this problem as they struggle to develop their economies at the expense of common resources. In addition, this article narrates the efforts that are exerted by governments in promoting coral reef protection and management of these coastal resources, setting the Apo Island in the Philippines as an example of good management and sustainability. PMID:12295817

Hinrichsen, D

1997-01-01

143

Coral Reef Ecosystems  

NASA Astrophysics Data System (ADS)

Coral reefs are geological structures of significant dimensions, constructed over millions of years by calcifying organisms. The present day reef-builders are hard corals belonging to the order Scleractinia, phylum Cnidaria. The greatest concentrations of coral reefs are in the tropics, with highest levels of biodiversity situated in reefs of the Indo-West Pacific region. These ecosystems have provided coastal protection and livelihood to human populations over the millennia. Human activities have caused destruction of these habitats, the intensity of which has increased alarmingly since the latter decades of the twentieth century. The severity of this impact is directly related to exponential growth rates of human populations especially in the coastal areas of the developing world. However, a more recently recognized phenomenon concerns disturbances brought about by the changing climate, manifested mainly as rising sea surface temperatures, and increasing acidification of ocean waters due to greater drawdown of higher concentrations of atmospheric carbon dioxide. Management efforts have so far not kept pace with the rates of degradation, so that the spatial extent of damaged reefs and the incidences of localized extinction of reef species are increasing year after year. The major management efforts to date consist of establishing marine protected areas and promoting the active restoration of coral habitats.

Yap, Helen T.

144

The Barrier Reef sediment apron: Tobacco Reef, Belize  

Microsoft Academic Search

Sedimentological and biological surveys of the back-reef sediment apron of Tobacco Reef, a continuous segment of the Belizean Barrier Reef, reveal five distinct biogeological zones: (1) coralline-coral-Dictyota pavement, (2) Turbinaria-Sargassum rubble, (3) Laurencia-Acanthophora sand and gravel, (4) bare sand and 95 Thalassia sand. These zones parallel the entire 9-km reef. The distribution of these zones is related to the spatial

Ian G. Macintyre; Richard R. Graus; Peter N. Reinthal; Mark M. Littler; Diane S. Littler

1987-01-01

145

Contradicting Barrier Reef relationships for Darwin's Evolution of reef types  

NASA Astrophysics Data System (ADS)

The Darwinian progressive subsidence model for the evolution of fringing reefs, barrier reefs and atolls has been generally accepted following the indisputable proof of subsidence provided by drilling results in the Pacific. Nonetheless, there are data that do not fit the expectations of the model, such as the similar lagoon depths of barrier reefs and atolls as opposed to the subsidence theory’s implicit prediction that atolls should have significantly greater depths. In contrast, a great deal of evidence supports the influence of meteoric solution on barrier reef morphology. For example, the maximum lagoon depth of 56 modern barrier reefs is statistically correlated with the lagoon catchment area for modern annual rainfall. These modern rainfall patterns would seem to be a reasonable proxy for relative geographic differences in glacial lowstand rainfall, even though the absolute amounts of such rainfall are unknown. The correlation therefore suggests the importance of Pleistocene subaerial solution in contributing to barrier reef morphology. Further support for antecedent influence occurs in the form of barrier reef passes in which the depth of the reef pass is correlated with onshore drainage volumes. On a larger scale, the Cook Island of Mangaia provides evidence that solution can produce barrier reef morphology independent of reef development. In contrast, there are no examples of the subsidence-predicted lagoon transition of fringing reefs to barrier reefs to atolls. Moreover, the common occurrence of fringing reefs within barrier reefs negates subsidence as a causal factor in their ‘presumed progressive evolutionary development. Consequently, the evidence to date suggests that a solution morphology template has been accentuated by reef construction to produce the diagnostic barrier reef morphology we see today. The importance of subsidence would seem to be in accounting for the overall thickness of the resulting carbonate caps of oceanic examples and in contributing to lagoon depth variation among the larger continental entities.

Purdy, Edward G.; Winterer, Edward L.

2006-02-01

146

High Latitude Reefs: A Potential Refuge for Reef Builders  

Microsoft Academic Search

Coral reefs globally show variable signs of deterioration or community structure changes due to a host of anthropogenic and natural factors. In these global scenarios, rates of calcification by reef builders such as Scleractinian corals are predicted to significantly decline in the future due to the increase in atmospheric CO_2. When considering the response of reefs to the present climate

A. Amat; N. Bates

2003-01-01

147

Carbonate Production by Coral Reefs.  

National Technical Information Service (NTIS)

In the paper, the authors first create hypothetical models of coral reefs, based upon carbonate production estimates for individual organisms; then they compare the models with what is known about real reef communities and their geologic histories. The di...

K. E. Chave S. V. Smith K. J. Roy

1971-01-01

148

Taphonomy of Reefs Through Time  

Microsoft Academic Search

\\u000a Reefs are susceptible to multiple physical, chemical and biological taphonomic processes. Bioerosion, in particular has escalated\\u000a through time and might be expected to have influenced the taphonomy of reefs. The following biases can be predicted: (1) In\\u000a the absence of grain-reducing activities by reef biota (fish, echinoids, and clionid sponges) abrasion on Paleozoic reefs\\u000a would have been dominated by physical

Rachel Wood

149

Coral reef hydrogeology  

SciTech Connect

Knowledge of internal flow velocities and pore water residence time is important in understanding pore water geochemistry, nutrient fluxes at the benthic boundary, reef diagenesis, and fresh water resources in reef islands. Hydrogeologic studies of Pacific and Indian Ocean reef and atoll islands indicate a dual aquifer systems; the major Pleistocene aquifer has hydraulic conductivities on the order of 1000 m/d, while the overlying Holocene aquifer of unconsolidated sediments is at least an order of magnitude less permeable. The high permeability in the Pleistocene formation is the result of large voids, both constructional and from subaerial solution during low stands of the sea. Wind, wave and tide induced head differences ranging from a few centimeters to several tens of centimeters provide the driving force for internal flow. Pore water residence times and geochemistry will vary greatly, depending on whether the water is in a major flow channel or in more restricted pores. Studies of both submerged reefs and atoll islands give bulk pore water residence times on the order of months to a few years. Chemical analyses of pore water indicate that both carbonate solution and precipitation are taking place, which will alter porosity and permeability with time. The dual aquifer model also suggests that the Ghyben-Herzberg lens approach to reef island fresh water resources is inaccurate and can lead to a gross overestimation of the potable resource. 18 refs., 5 figs.

Buddemeier, R.W.; Oberdorfer, J.A.

1985-05-21

150

Reefs at risk.  

PubMed

Coral reefs, considered the rainforests of the seas, are home to a diverse number of marine species. These reefs are tightly woven ecosystems with complex linkages, which, if disturbed, result in an unpleasant chain of events. Furthermore, these reefs are the main source of animal protein for more than a billion people. Aside from supplying food, they stabilize shorelines and protect the land from rising seas and storm damage. Also, they provide sources of medicines used for bone grafts and treatment for certain viruses. However, these reefs are in danger of being permanently damaged as a result of natural and man-made forces. In response to this threat, most marine scientists have suggested that local communities be involved in the implementation and management of programs, with the aim of achieving sustainable reef maintenance. In addition, international agencies have taken the initiative to finance such programs to ensure their continuity. Overall, the management and development of coastal ecosystems depend on how they are managed and not on how they are being exploited. Resources must be rebuilt and their protection ensured for future generations. PMID:12322541

Hinrichsen, D

1999-01-01

151

Variation in emergence of parasitic and predatory isopods among habitats at Lizard Island, Great Barrier Reef  

Microsoft Academic Search

Gnathiid isopods are one of the most abundant groups of ectoparasites on coral reef fishes. They, and other isopods, have\\u000a been shown to significantly affect the health and behaviour of many reef fish. Whether isopod emergence differs among habitats\\u000a on coral reefs is not known. In this study, we measured emergence rates of parasitic isopods (Gnathiidea and Flabellifera)\\u000a in six

C. M. Jones; A. S. Grutter

2007-01-01

152

Heuristic Abstraction in the Decision-Theoretic Pathfinder System*  

PubMed Central

A criticism of diagnostic systems, which are based on the formal foundations of probability and utility, is that their reasoning strategies and recommendations are inflexible and unnatural. We have developed a facility that increases the flexibility of normative reasoning systems by providing multiple human-oriented perspectives on diagnostic problem solving. The method endows a system with the ability to reason about arbitrary classes of diagnostic entities and to control the level of abstraction at which inference occurs. The techniques have been integrated into Pathfinder, an expert system that performs hematopathology diagnosis. We explain the background and approach that we have taken, and describe how we use the techniques in Pathfinder to modulate information- and decision-theoretic reasoning with strategic scripts that are familiar to physicians.

Horvitz, Eric J.; Heckerman, David E.; Ng, Keung-Chi; Nathwani, Bharat N.

1989-01-01

153

SHUTDOWN COOLING TEST. Pathfinder Atomic Power Plant Summary Report  

Microsoft Academic Search

Tests are performed on Pathfinder superheat fuel element mockups, under ;\\u000a reactor conditions of 600 psig, in order to determine the parameters influencing ;\\u000a heat transfer from the fuel elements to the moderating water under shutdown ;\\u000a conditions. The peak temperatures reached by the superheat elements are also ;\\u000a found as functions of the heat generation rate. A mathematical model

W. E. Littleton; W. Ross

1961-01-01

154

Pathfinder: A parallel search algorithm for concerted atomistic events  

Microsoft Academic Search

An algorithm has been designed to search for the escape paths with the lowest activation barriers when starting from a local minimum-energy configuration of a many-atom system. The pathfinder algorithm combines: (1) a steered eigenvector-following method that guides a constrained escape from the convex region and subsequently climbs to a transition state tangentially to the eigenvector corresponding to the lowest

Aiichiro Nakano

2007-01-01

155

Characteristics of the TOVS Pathfinder Path A Dataset  

Microsoft Academic Search

The TIROS (Television Infrared Observation Satellite) Operational Vertical Sounder (TOVS) Pathfinder Path A dataset is currently a 9-yr dataset, 1985-93, of global fields of surface and atmospheric parameters derived from analysis of HIRS2 and MSU data on the NOAA-9, NOAA-10, NOAA-11, and NOAA-12 polar-orbiting operational meteorological satellites. The retrieved fields include land and ocean surface skin temperature, atmospheric temperature and

J. Susskind; P. Piraino; L. Rokke; L. Iredell; A. Mehta

1997-01-01

156

Development and evaluation of the mars pathfinder inflatable airbag landing system  

Microsoft Academic Search

The entry, descent, and landing system of the Mars Pathfinder spacecraft includes a unique subsystem of airbags for impact attenuation. The airbag geometric configuration and associated landing dynamic analysis was performed by the Jet Propulsion Laboratory and Sandia National Laboratories (Mars pathfinder airbag impact attenuation system, paper AIAA-95-1552; Mars pathfinder impact, paper AIAA-95-1553). ILC Dover performed detailed design and fabrication

D. Cadogan; C. Sandy; M. Grahne

2002-01-01

157

The Tangible Pathfinder Design of a Wayfinding Trainer for the Visually Impaired  

Microsoft Academic Search

We detail our proposal for an orientation and mobility (or wayfinding) trainer for the visually impaired—the Tangible Pathfinder. The Tangible Pathfinder allows autonomous learning of a new setting, self-assessment of the resulting cognitive map, and eventually on-site mobility assistance when physically walking through the environment. The Tangible Pathfinder integrates a tablet-like tangible user interface (TUI) which tracks a set of

Ehud Sharlin; Yoshifumi Kitamura; Darren Rorabeck; Robert Lederer; Steve Sutphen; Masafumi Takimoto; Fumio Kishino

158

Gray's Reef Research  

NSDL National Science Digital Library

Provides a sampling of research projects conducted at the Gray's Reef National Marine Sanctuary off Georgia's Sapelo Island. Projects range from geology to trawling impacts on the seafloor, estimating fish populations by video transect, Sanctuary monitoring using data buoys, sidescan sonar and other technologies. Examples of current projects: conducting a study on the movement patterns of fish in the area; efforts to understand the roles of "choices" fishes might make in their behaviors, and its impact on diversity of species found in reef fish communities and a study designed to inventory the invertebrates and fish communities and analyze how those communities are impacted by fishing activities. Appropriate for grades 9 and up.

159

The evolution of reef communities  

SciTech Connect

This book discusses the composition, structure, occurrence, and changes in reefs during the past 2 billion years. It emphasizes the functional roles of major groups (guilds) of reef-building, reef-destroying, and reed-dwelling organisms in the most complex of all marine communities. A structural model, based on modern reef guilds, is developed. Then the functional roles of each major reef-building higher biologic taxon (algae, sponges, coral, etc.) is determined, and, on this basis, each such taxon is assigned to a reef community guild. Next, the authors traces the geologic history and guild assignment of each major taxon through geologic time. The final chapter establishes a succession of ten major reef community types, and considers their extinction and recovery in the light of modern theories of cosmic and earthly events.

Fagerstrom, J.A.

1987-01-01

160

Sewage impacts coral reefs at multiple levels of ecological organization.  

PubMed

Against a backdrop of rising sea temperatures and ocean acidification which pose global threats to coral reefs, excess nutrients and turbidity continue to be significant stressors at regional and local scales. Because interventions usually require local data on pollution impacts, we measured ecological responses to sewage discharges in Surin Marine Park, Thailand. Wastewater disposal significantly increased inorganic nutrients and turbidity levels, and this degradation in water quality resulted in substantial ecological shifts in the form of (i) increased macroalgal density and species richness, (ii) lower cover of hard corals, and (iii) significant declines in fish abundance. Thus, the effects of nutrient pollution and turbidity can cascade across several levels of ecological organization to change key properties of the benthos and fish on coral reefs. Maintenance or restoration of ecological reef health requires improved wastewater management and run-off control for reefs to deliver their valuable ecosystems services. PMID:19515390

Reopanichkul, Pasinee; Schlacher, Thomas A; Carter, R W; Worachananant, Suchai

2009-06-09

161

Reef Fishes of Saba Bank, Netherlands Antilles: Assemblage Structure across a Gradient of Habitat Types  

PubMed Central

Saba Bank is a 2,200 km2 submerged carbonate platform in the northeastern Caribbean Sea off Saba Island, Netherlands Antilles. The presence of reef-like geomorphic features and significant shelf edge coral development on Saba Bank have led to the conclusion that it is an actively growing, though wholly submerged, coral reef atoll. However, little information exists on the composition of benthic communities or associated reef fish assemblages of Saba Bank. We selected a 40 km2 area of the bank for an exploratory study. Habitat and reef fish assemblages were investigated in five shallow-water benthic habitat types that form a gradient from Saba Bank shelf edge to lagoon. Significant coral cover was restricted to fore reef habitat (average cover 11.5%) and outer reef flat habitat (2.4%) and declined to near zero in habitats of the central lagoon zone. Macroalgae dominated benthic cover in all habitats (average cover: 32.5 – 48.1%) but dominant algal genera differed among habitats. A total of 97 fish species were recorded. The composition of Saba Bank fish assemblages differed among habitat types. Highest fish density and diversity occurred in the outer reef flat, fore reef and inner reef flat habitats. Biomass estimates for commercially valued species in the reef zone (fore reef and reef flat habitats) ranged between 52 and 83 g/m2. The composition of Saba Bank fish assemblages reflects the absence of important nursery habitats, as well as the effects of past fishing. The relatively high abundance of large predatory fish (i.e. groupers and sharks), which is generally considered an indicator of good ecosystem health for tropical reef systems, shows that an intact trophic network is still present on Saba Bank.

Toller, Wes; Debrot, Adolphe O.; Vermeij, Mark J. A.; Hoetjes, Paul C.

2010-01-01

162

Coral Reef Biological Criteria  

EPA Science Inventory

Coral reefs worldwide are experiencing decline from a variety of stressors. Some important stressors are land-based sources of pollution and human activities in the coastal zone. However, few tools are available to offset the impact of these stressors. The Clean Water Act (CWA...

163

Upper Permian Capitan Reef  

Microsoft Academic Search

A depositional and diagentic model for the Capitan reef complex (Late Permian, Guadalupian age) has evolved during more than 50 years of outcrop studies in the Guadalupe Mountains of west Texas and New Mexico. The model relates the shelf margin (Capitain Limestone) with equivalent shelf (in ascending order, Seven Rivers, Yates, and Tansill Formations) and basin (Bell Canyon Formation) strata.

P. M. Harris; R. A. Garber; G. A. Grover

1988-01-01

164

Miocene reefs in western Mediterranean  

SciTech Connect

Coral reefs were particularly abundant and well developed during the late Tortonian and Messinian in southeastern Spain, the Balearic Islands, Italy, Sicily, Algeria, and Morocco. These reefs occurred just before and during the deposition of the thick Messinian evaporite units in the basinal areas and disappeared completely from Mediteranean during the early Pliocene. Most of the coral reefs are fringing terrigenous coastal fan complexes with very small lagoons and show progradation of less than 2 km. Some of the reefs occur on, or are intercalated with, Neogene volcanics or Messinian evaporites. Barrier-reef complexes are less common, have extensive lagoons behind them, and show complex progradational geometries more than 10 km wide. Excellent outcrops allow detailed reconstruction of paleogeography and sea level changes. Progradation predominated during phases of relative sea level drops and stillsands, while significant retrogradation occurred during sea level rises. The coral reef wall framework is commonly less than 20 m thick and is dominated by Porites and, locally, Tarbellastrae. Older Miocene reefs are less well developed, but show greater diversity of corals and reef organisms. Younger Miocene reef complexes occurring in open ocean settings are formed by only one branching coral genus (Porites or, locally, Tarbellastraea) with branching colonies up to 7 m high. Halimeda sands are particularly abundant in the upper reef slopes with occasional intercalations of red algae pavements that most likely coincide with episodes of terrigenous influx.

Esteban, M.

1988-01-01

165

Assessing the ecological risk of creating artificial reefs from ex-warships  

Microsoft Academic Search

Inactive warships would make excellent artificial reefs in coastal waters if preliminary data suggesting that they pose no threat to human health or the environment from contamination can be confirmed. A screening level ecorisk assessment was conducted on data from artificial reefs composed of ex-warships located off the coast of South Carolina to assess the potential risk of contamination from

R. K. Johnston; H. Halkola; R. Gauthier; W. Wild; M. Bell; R. Martore

2003-01-01

166

Terrigenous Sediment Provenance from Geochemical Tracers, South Molokai Reef Flat, Hawaii.  

National Technical Information Service (NTIS)

Land-derived runoff is one of the greatest threats to coral-reef health. Identification of runoff sources is an important step in erosion mitigation efforts. A geochemical sediment provenance study was done in uplands and across the adjacent fringing reef...

R. K. Takesue

2010-01-01

167

Geochemical Records of Bleaching Events and the Associated Stressors From the Great Barrier Reef  

Microsoft Academic Search

The health of coral reefs world-wide is increasingly threatened by a wide array of stressors. On the Great Barrier Reef (GBR) these stressors include increased sediment flux associated with land use changes, increased sea surface temperatures (SST) and salinity changes due to large floods, the latter two of which are factors in an increased number of bleaching events. The ability

E. B. Roark; M. McCulloch; B. L. Ingram; J. F. Marshall

2003-01-01

168

An observational heat budget analysis of a coral reef, Heron Reef, Great Barrier Reef, Australia  

NASA Astrophysics Data System (ADS)

Measurements of the surface energy balance, the structure and evolution of the convective atmospheric reef layer (CARL), and local meteorology and hydrodynamics were made during June 2009 and February 2010 at Heron Reef, Australia, to establish the relative partitioning of heating within the water and atmosphere. Horizontal advection was shown to moderate temperature in the CARL and the water, having a cooling influence on the atmosphere, and providing an additional source or sink of energy to the water overlying the reef, depending on tide. The key driver of atmospheric heating was surface sensible heat flux, while heating of the reef water was primarily due to solar radiation, and thermal conduction and convection from the reef substrate. Heating and cooling processes were more defined during winter due to higher sensible and latent heat fluxes and strong diurnal evolution of the CARL. Sudden increases in water temperature were associated with inundation of warmer oceanic water during the flood tide, particularly in winter due to enhanced nocturnal cooling of water overlying the reef. Similarly, cooling of the water over the reef occurred during the ebb tide as heat was transported off the reef to the surrounding ocean. While these results are the first to shed light on the heat budget of a coral reef and overlying CARL, longer-term, systematic measurements of reef thermal budgets are needed under a range of meteorological and hydrodynamic conditions, and across various reef types to elucidate the influence on larger-scale oceanic and atmospheric processes. This is essential for understanding the role of coral reefs in tropical and sub-tropical meteorology; the physical processes that take place during coral bleaching events, and coral and algal community dynamics on coral reefs.

MacKellar, Mellissa C.; McGowan, Hamish A.; Phinn, Stuart R.

2013-03-01

169

International Society for Reef Studies  

NSDL National Science Digital Library

Located within the Florida Institute of Technology, the International Society for Reef Studies (ISRS) was founded in 1980, and is designed to disseminate its findings on both living and fossil coral reefs to fellow scholars around the globe and the general public. Before delving into the main site, visitors will want to look through the ISRS in-house publication "Reef Encounters" to get a sense of the various projects the organization is currently working on, and of course, to read brief summaries of its research findings. Of course, for those who already are passionate about coral reefs, there is also a link to sign up for the NOAA "Coral List" forum. The resources section of the site is another good place to look for outside Web resources on other coral reef societies, marine laboratories, and government sites that contain materials on coral reefs and marine biology.

170

Middle East Pathfinder: Fiction and Nonfiction Resources for K-12 Educators.  

ERIC Educational Resources Information Center

This paper describes a resource tool called a pathfinder, which is a specialized bibliography used by public, academic, and school librarians to compile related information into a single document, usually under 10 pages. This Middle East Pathfinder contains 14 types of information sources including: (1) a brief introduction to the topic with…

Duffy, Paula, Comp.

171

PathFinder: a negotiation-based performance-driven router for FPGAs  

Microsoft Academic Search

Routing FPGAs is a challenging problem because of the relative scarcity of routing resources, both wires and connection points. This can lead either to slow implementations caused by long wiring paths that avoid congestion or a failure to route all signals. This paper presents PathFinder, a router that balances the goals of performance and routability. PathFinder uses an iterative algorithm

Larry McMurchie; Carl Ebeling

1995-01-01

172

Final chemical results from the Mars Pathfinder alpha proton X-ray spectrometer  

Microsoft Academic Search

The calibrated Pathfinder alpha proton X-ray spectrometer (APXS) instrument is capable of measuring concentrations of all major and minor rock-forming elements ranging from carbon through zirconium in atomic number. Therefore it is capable of constraining the petrology of the measured samples. In particular, the Pathfinder data are the first in situ measurements of Martian rocks and may be compared with

C. Nicole Foley; Thanasis Economou; Robert N. Clayton

2003-01-01

173

Spatial Resilience of Coral Reefs  

Microsoft Academic Search

There have been several earlier studies that addressed the influence of natural disturbance regimes on coral reefs. Humans\\u000a alter natural disturbance regimes, introduce new stressors, and modify background conditions of reefs. We focus on how coral\\u000a reef ecosystems relate to disturbance in an increasingly human-dominated environment. The concept of ecosystem resilience—that\\u000a is, the capacity of complex systems with multiple stable

Magnus Nyström; Carl Folke

2001-01-01

174

The Paleoecology of Coral Reefs  

Microsoft Academic Search

\\u000a Reefs are one of the oldest ecosystems in the world, and coral reefs have had a rich and varied history over hundreds of millions\\u000a of years. The long-term history of living reef organisms provides an essential window in which to view a number of fundamental\\u000a evolutionary and ecological processes over extended time frames not available to modern ecology over years

John M. Pandolfi

175

THE ECOLOGICAL EVOLUTION OF REEFS  

Microsoft Academic Search

Many groups of extinct and extant organisms have aggregated to form reefs for over 3.5 billion yr (Ga). Most of these communities, however, grew under eco- logical and environmental controls profoundly different from those that govern modern coral reefs. Not only has the global distribution of reefs varied consid- erably through geological time—determined largely by sea level, and latitudinal temperature\\/saturation

Rachel Wood

1998-01-01

176

Digital reef rugosity estimates coral reef habitat complexity.  

PubMed

Ecological habitats with greater structural complexity contain more species due to increased niche diversity. This is especially apparent on coral reefs where individual coral colonies aggregate to give a reef its morphology, species zonation, and three dimensionality. Structural complexity is classically measured with a reef rugosity index, which is the ratio of a straight line transect to the distance a flexible chain of equal length travels when draped over the reef substrate; yet, other techniques from visual categories to remote sensing have been used to characterize structural complexity at scales from microhabitats to reefscapes. Reef-scale methods either lack quantitative precision or are too time consuming to be routinely practical, while remotely sensed indices are mismatched to the finer scale morphology of coral colonies and reef habitats. In this communication a new digital technique, Digital Reef Rugosity (DRR) is described which utilizes a self-contained water level gauge enabling a diver to quickly and accurately characterize rugosity with non-invasive millimeter scale measurements of coral reef surface height at decimeter intervals along meter scale transects. The precise measurements require very little post-processing and are easily imported into a spreadsheet for statistical analyses and modeling. To assess its applicability we investigated the relationship between DRR and fish community structure at four coral reef sites on Menjangan Island off the northwest corner of Bali, Indonesia and one on mainland Bali to the west of Menjangan Island; our findings show a positive relationship between DRR and fish diversity. Since structural complexity drives key ecological processes on coral reefs, we consider that DRR may become a useful quantitative community-level descriptor to characterize reef complexity. PMID:23437380

Dustan, Phillip; Doherty, Orla; Pardede, Shinta

2013-02-21

177

Local Translation and mRNA Trafficking in Axon Pathfinding  

Microsoft Academic Search

Axons and their growth cones are specialized neuronal sub-compartments that possess translation machinery and have distinct\\u000a messenger RNAs (mRNAs). Several classes of mRNAs have been identified using candidate-based, as well as unbiased genome-wide-based\\u000a approaches. Axonal mRNA localization serves to regulate spatially the protein synthesis; thereby, providing axons with a high\\u000a degree of functional autonomy from the soma during axon pathfinding.

Byung C. Yoon; Krishna H. Zivraj; Christine E. Holt

178

Teacher/Pathfinder: An Educational Internet Village  

NSDL National Science Digital Library

This well-organized and very useful metasite has something for everyone involved in K-12 education professionally or as a parent. The site is essentially a collection of links to a large number of on-line resources grouped in five categories. The Community Center currently offers two topics: Improving Education and Model Consortia, the first containing a large number of Department of Education publications. The Support Offices section contains resources of interest to a variety of K-12 professionals: teachers, librarians, administrators, and nurses. The Schoolhouse is appropriately the largest area, and it features assessment and general education tools as well as subject area resources, including social studies and technology. Visitors to the Parent Building will find a list of Family-Friendly Internet Sites, tips for involving the family in education, and Family Health Resources. Finally, the Professional Development section covers a number of topics, including tutorials for using technology in education. This metasite is especially recommended because unlike many other K-12 sites, it aims beyond the teachers and includes valuable information for families and all K-12 professionals.

179

Microbial photosynthesis in coral reef sediments (Heron Reef, Australia)  

Microsoft Academic Search

We investigated microphytobenthic photosynthesis at four stations in the coral reef sediments at Heron Reef, Australia. The microphytobenthos was dominated by diatoms, dinoflagellates and cyanobacteria, as indicated by biomarker pigment analysis. Conspicuous algae firmly attached to the sand grains (ca. 100?m in diameter, surrounded by a hard transparent wall) were rich in peridinin, a marker pigment for dinoflagellates, but also

Ursula Werner; Anna Blazejak; Paul Bird; Gabriele Eickert; Raphaela Schoon; Raeid M. M. Abed; Andrew Bissett; Dirk de Beer

2008-01-01

180

Management of coral reefs: We have gone wrong when neglecting active reef restoration  

Microsoft Academic Search

The current best management tools employed in coral reefs worldwide do not achieve conservation objectives as coral reefs continue to degrade. Even improved reef management helps, at best, to reduce the degradation pace, whereas the worsening global changes foretell a dismal fate for coral reefs. The assertion made here is that the prospect for reefs’ future is centered on omnipresent

Baruch Rinkevich

2008-01-01

181

Career pathfinders: a qualitative study of career development.  

PubMed

This paper examined the perceptions of career path and issues of MBA students in response to Lore's The Pathfinder, a comprehensive career-planning model. Using internet discussion boards, an interactive dialogue was mentioned by participants in response to the components of Lore's model. The sample consisted of 50 fully employed MBA students enrolled in a course on self-assessment and career planning. A total of 1,781 separate postings were made and analyzed, using inductive analysis derived from discussion threads based on Lore's categories: comments on Lore's Pathfinder model, living a life you love (what's the holdup, career fantasies, work and family issues, and career selection), how to get there from here (commitment and future from the present), and designing your future career. Findings indicated several interesting trends in the career planning of current MBA students, particularly the importance of self or self-reflective observations in real time as students who are also fully employed formulate career plans. Implications for psychologists and career counselors, career development models, and suggestions for research are presented. PMID:16796109

Beutell, Icholas J; O'Hare, Marianne M

2006-04-01

182

Case for testing modified Newtonian dynamics using LISA pathfinder  

NASA Astrophysics Data System (ADS)

We quantify the potential for testing modified Newtonian dynamics (MOND) with Laser Interferometer Space Antenna pathfinder, should a saddle point fly-by be incorporated into the mission. We forecast the expected signal-to-noise ratio for a variety of instrument noise models and trajectories past the saddle. For standard theoretical parameters, the signal-to-noise ratio reaches middle to high double figures even with modest assumptions about instrument performance and saddle approach. Obvious concerns, like systematics arising from Laser Interferometer Space Antenna pathfinder self-gravity, or the Newtonian background, are examined and shown not to be a problem. We also investigate the impact of a negative observational result upon the free function determining the theory. We demonstrate that, if Newton’s gravitational constant is constrained to not be renormalized by more than a few percent, only contrived MONDian free functions would survive a negative result. There are exceptions, e.g. free functions not asymptoting to 1 in the Newtonian limit, but rather diverging or asymptoting to zero (depending on their mother relativistic MONDian theory). Finally, we scan the structure of all proposed relativistic MONDian theories, and classify them with regards to their nonrelativistic limit, finding three broad cases (with a few subcases depending on the form of the free function). It is appears that only the Einstein-Aether formulation, and the subcases where the free function does not asymptote to 1 in other theories, would survive a negative result without resorting to “designer” free functions.

Magueijo, João; Mozaffari, Ali

2012-02-01

183

Mars Pathfinder and Mars Global Surveyor Outreach Compilation  

NASA Astrophysics Data System (ADS)

This videotape is a compilation of the best NASA JPL (Jet Propulsion Laboratory) videos of the Mars Pathfinder and Mars Global Surveyor missions. The mission is described using animation and narration as well as some actual footage of the entire sequence of mission events. Included within these animations are the spacecraft orbit insertion; descent to the Mars surface; deployment of the airbags and instruments; and exploration by Sojourner, the Mars rover. JPL activities at spacecraft control during significant mission events are also included at the end. The spacecraft cameras pan the surrounding Mars terrain and film Sojourner traversing the surface and inspecting rocks. A single, brief, processed image of the Cydonia region (Mars face) at an oblique angle from the Mars Global Surveyor is presented. A description of the Mars Pathfinder mission, instruments, landing and deployment process, Mars approach, spacecraft orbit insertion, rover operation are all described using computer animation. Actual color footage of Sojourner as well as a 360 deg pan of the Mars terrain surrounding the spacecraft is provided. Lower quality black and white photography depicting Sojourner traversing the Mars surface and inspecting Martian rocks also is included.

1999-09-01

184

Development of memory structures for homographs using pathfinder network representations.  

PubMed

Some studies with children have shown that there is no semantic priming at short stimulus onset asynchrony (SOA) in lexical decision and naming tasks for homographs. The predictions of spreading activation theories might explain this missing effect. There may be differences in children's and adults' memory structures. We have explored this hypothesis. The development of memory structure representations for homographs was measured by a Pathfinder algorithm. In Experiment 1, the three dependent variables were: the number of links in the network, closeness measures (C), and distances between nodes. Results revealed developmental differences in network structure representations in adults and children. In Experiment 2, results revealed that these differences were not due to the cohort effect. In Experiment 3, the relationship between associative strength, as measured by associative norms, and distances, as measured by Pathfinder algorithm, was explored. The results of these three experiments and empirical research from semantic priming experiments show that these differences in memory structure representations could be one of the sources of the missing semantic priming effect in children. PMID:12765048

Nievas, Francisco; Justicia, Fernando

2003-05-01

185

Black reefs: iron-induced phase shifts on coral reefs.  

PubMed

The Line Islands are calcium carbonate coral reef platforms located in iron-poor regions of the central Pacific. Natural terrestrial run-off of iron is non-existent and aerial deposition is extremely low. However, a number of ship groundings have occurred on these atolls. The reefs surrounding the shipwreck debris are characterized by high benthic cover of turf algae, macroalgae, cyanobacterial mats and corallimorphs, as well as particulate-laden, cloudy water. These sites also have very low coral and crustose coralline algal cover and are call black reefs because of the dark-colored benthic community and reduced clarity of the overlying water column. Here we use a combination of benthic surveys, chemistry, metagenomics and microcosms to investigate if and how shipwrecks initiate and maintain black reefs. Comparative surveys show that the live coral cover was reduced from 40 to 60% to <10% on black reefs on Millennium, Tabuaeran and Kingman. These three sites are relatively large (>0.75 km(2)). The phase shift occurs rapidly; the Kingman black reef formed within 3 years of the ship grounding. Iron concentrations in algae tissue from the Millennium black reef site were six times higher than in algae collected from reference sites. Metagenomic sequencing of the Millennium Atoll black reef-associated microbial community was enriched in iron-associated virulence genes and known pathogens. Microcosm experiments showed that corals were killed by black reef rubble through microbial activity. Together these results demonstrate that shipwrecks and their associated iron pose significant threats to coral reefs in iron-limited regions. PMID:21881615

Kelly, Linda Wegley; Barott, Katie L; Dinsdale, Elizabeth; Friedlander, Alan M; Nosrat, Bahador; Obura, David; Sala, Enric; Sandin, Stuart A; Smith, Jennifer E; Vermeij, Mark J A; Williams, Gareth J; Willner, Dana; Rohwer, Forest

2011-09-01

186

Using coral disease prevalence to assess the effects of concentrating tourism activities on offshore reefs in a tropical marine park.  

PubMed

Concentrating tourism activities can be an effective way to closely manage high-use parks and minimize the extent of the effects of visitors on plants and animals, although considerable investment in permanent tourism facilities may be required. On coral reefs, a variety of human-related disturbances have been associated with elevated levels of coral disease, but the effects of reef-based tourist facilities (e.g., permanent offshore visitor platforms) on coral health have not been assessed. In partnership with reef managers and the tourism industry, we tested the effectiveness of concentrating tourism activities as a strategy for managing tourism on coral reefs. We compared prevalence of brown band disease, white syndromes, black band disease, skeletal eroding band, and growth anomalies among reefs with and without permanent tourism platforms within the Great Barrier Reef Marine Park. Coral diseases were 15 times more prevalent at reefs with offshore tourism platforms than at nearby reefs without platforms. The maximum prevalence and maximum number of cases of each disease type were recorded at reefs with permanently moored tourism platforms. Diseases affected 10 coral genera from 7 families at reefs with platforms and 4 coral genera from 3 families at reefs without platforms. The greatest number of disease cases occurred within the spatially dominant acroporid corals, which exhibited 18-fold greater disease prevalence at reefs with platforms than at reefs without platforms. Neither the percent cover of acroporids nor overall coral cover differed significantly between reefs with and without platforms, which suggests that neither factor was responsible for the elevated levels of disease. Identifying how tourism activities and platforms facilitate coral disease in marine parks will help ensure ongoing conservation of coral assemblages and tourism. PMID:21848962

Lamb, Joleah B; Willis, Bette L

2011-08-16

187

Adaptive Avoidance of Reef Noise  

Microsoft Academic Search

Auditory information is widely used throughout the animal kingdom in both terrestrial and aquatic environments. Some marine species are dependent on reefs for adult survival and reproduction, and are known to use reef noise to guide orientation towards suitable habitat. Many others that forage in food-rich inshore waters would, however, benefit from avoiding the high density of predators resident on

Stephen D. Simpson; Andrew N. Radford; Edward J. Tickle; Mark G. Meekan; Andrew G. Jeffs; A. Peter Klimley

2011-01-01

188

Perspectives in coral reef hydrodynamics  

NASA Astrophysics Data System (ADS)

Some developments in coral reef hydrodynamics over the last decade are reviewed with an overview of papers in this special issue. Advances in hydrodynamics based on improved understanding of topographic complexity are illustrated for the reef at Kilo Nalu Observatory and Kaneohe Bay (both in Hawaii). Models of the roughness layer are discussed as a background to numerical models of reef hydrodynamics for Molokai and Guam. Topographic complexity produces spatial temperature variability over reefs creating thermal microclimates which are reported in this issue for the Red Sea. Uptake of ocean nutrients by reefs is controlled by hydrodynamics, and papers in this issue show its critical role in the ecology of a fringing reef at La Réunion Island; nutrient uptake rates are discussed here using new data for Hearn Roughness and Decadal Rugosity. The role of upwelled water by large amplitude internal waves on reefs is reported for the Similan Islands, providing major new evidence for the role of hydrodynamics in the ecology of reefs and its importance to climate change. The review suggests some important areas for new research including simulated corals used in flumes and the field. Major new modeling based on measured roughness maps combined with small scale lattice Boltzmann simulations should be possible in the next decade.

Hearn, Clifford J.

2011-06-01

189

Development of Artificial Oyster Reefs.  

National Technical Information Service (NTIS)

One hundred fourteen acres of public oyster reefs were constructed at an average cost of $1,867/acre in Bay, Brevard, Franklin, Wakulla, and Walton Counties, Florida. These reefs were constructed using 402,244 bushels of shucked Callico scallop shell, and...

W. K. Whitfield

1978-01-01

190

Coral reefs and carbon dioxide  

SciTech Connect

This commentary argues the conclusion from a previous article, which investigates diurnal changes in carbon dioxide partial pressure and community metabolism on coral reefs, that coral `reefs might serve as a sink, not a source, for atmospheric carbon dioxide.` Commentaries from two groups are given along with the response by the original authors, Kayanne et al. 27 refs.

Buddemeier, R.W. [Kansas Geological Survey, Lawrence, KS (United States)

1996-03-01

191

Confronting the coral reef crisis  

Microsoft Academic Search

The worldwide decline of coral reefs calls for an urgent reassessment of current management practices. Confronting large-scale crises requires a major scaling-up of management efforts based on an improved understanding of the ecological processes that underlie reef resilience. Managing for improved resilience, incorporating the role of human activity in shaping ecosystems, provides a basis for coping with uncertainty, future changes

T. P. Hughes; C. Folke; M. Nyström; D. R. Bellwood

2004-01-01

192

REEF CORALS : AUTOTROPHS OR HETEROTROPHS?  

Microsoft Academic Search

Some recent studies 2 seem to indicate that the nutritional economy of reef corals is for all practical purposes to be considered autotrophic due to their zooxanthellae (Fig. 1). For example, Franzisket (1969a, 1970) claims to have demonstrated that some Hawaiian reef corals can achieve net growth in the total absence of particulate food, while Johannes and Coles ( 1969)

THOMAS F. GOREAU; NORA I. GOREAU; C. M. YONGE

1971-01-01

193

Biomass of suspended bacteria over coral reefs  

Microsoft Academic Search

The biomass of bacteria suspended in water flowing over coral reefs at Lizard Island and Yonge Reef (Northern Great Barrier Reef) was estimated by measurement of muramic acid. Values ranged from 20 mg C m-3 in the open water up to about 60 mg C m-3 over the reef flat. Direct counts of total numbers of free bacteria were made

D. J. W. Moriarty

1979-01-01

194

Miocene precursors to Great Barrier Reef  

Microsoft Academic Search

Huge reefs of Miocene age are present in the Gulf of Papua north of the present-day Great Barrier Reef and to the east on the Marion and Queensland Plateaus. In the Gulf of Papua, Miocene barrier reefs formed the northern forerunner of the Great Barrier Reef, extending for many hundreds of kilometers along the eastern and northern margin of the

P. J. Davies; P. A. Symonds; D. A. Feary; C. Pigram

1988-01-01

195

Assessing the Ecological Risk of Creating Artificial Reefs from ex- Warships.  

National Technical Information Service (NTIS)

Inactive warships would make excellent artificial reefs in coastal waters if preliminary data suggesting that they pose no threat to human health or the environment from contamination can be confirmed. A screening level ecorisk assessment was conducted on...

C. In H. Halkola R. Gauthier R. George R. K. Johnston

2003-01-01

196

Capitol Reef National Park  

NSDL National Science Digital Library

This National Park Service (NPS) website provides an in-depth look at Capitol Reef National Park in Utah. Specifically, this covers the geology and natural resources of the park. There is a general overview of the geology of this area including the Waterpocket fold, Colorado Plateau, Cathedral Valley and erosion. There is a description of various rock colors and how they form, as well as a detailed stratigraphic column illustrating the names, thicknesses, and ancient environments of rocks and formations that exist in the park. The Natural Resources section discusses some of the history and archeology of the park, as well as birds, mammals, plants, reptiles and environmental problems.

197

Adaptive Avoidance of Reef Noise  

PubMed Central

Auditory information is widely used throughout the animal kingdom in both terrestrial and aquatic environments. Some marine species are dependent on reefs for adult survival and reproduction, and are known to use reef noise to guide orientation towards suitable habitat. Many others that forage in food-rich inshore waters would, however, benefit from avoiding the high density of predators resident on reefs, but nothing is known about whether acoustic cues are used in this context. By analysing a sample of nearly 700,000 crustaceans, caught during experimental playbacks in light traps in the Great Barrier Reef lagoon, we demonstrate an auditory capability in a broad suite of previously neglected taxa, and provide the first evidence in any marine organisms that reef noise can act as a deterrent. In contrast to the larvae of species that require reef habitat for future success, which showed an attraction to broadcasted reef noise, taxa with a pelagic or nocturnally emergent lifestyle actively avoided it. Our results suggest that a far greater range of invertebrate taxa than previously thought can respond to acoustic cues, emphasising yet further the potential negative impact of globally increasing levels of underwater anthropogenic noise.

Simpson, Stephen D.; Radford, Andrew N.; Tickle, Edward J.; Meekan, Mark G.; Jeffs, Andrew G.

2011-01-01

198

The LISA Pathfinder interferometry—hardware and system testing  

NASA Astrophysics Data System (ADS)

Preparations for the LISA Pathfinder mission have reached an exciting stage. Tests of the engineering model (EM) of the optical metrology system have recently been completed at the Albert Einstein Institute, Hannover, and flight model tests are now underway. Significantly, they represent the first complete integration and testing of the space-qualified hardware and are the first tests on an optical system level. The results and test procedures of these campaigns will be utilized directly in the ground-based flight hardware tests, and subsequently during in-flight operations. In addition, they allow valuable testing of the data analysis methods using the MATLAB-based LTP data analysis toolbox. This paper presents an overview of the results from the EM test campaign that was successfully completed in December 2009.

Audley, H.; Danzmann, K.; García Marín, A.; Heinzel, G.; Monsky, A.; Nofrarias, M.; Steier, F.; Gerardi, D.; Gerndt, R.; Hechenblaikner, G.; Johann, U.; Luetzow-Wentzky, P.; Wand, V.; Antonucci, F.; Armano, M.; Auger, G.; Benedetti, M.; Binetruy, P.; Boatella, C.; Bogenstahl, J.; Bortoluzzi, D.; Bosetti, P.; Caleno, M.; Cavalleri, A.; Cesa, M.; Chmeissani, M.; Ciani, G.; Conchillo, A.; Congedo, G.; Cristofolini, I.; Cruise, M.; De Marchi, F.; Diaz-Aguilo, M.; Diepholz, I.; Dixon, G.; Dolesi, R.; Fauste, J.; Ferraioli, L.; Fertin, D.; Fichter, W.; Fitzsimons, E.; Freschi, M.; García Marirrodriga, C.; Gesa, L.; Gibert, F.; Giardini, D.; Grimani, C.; Grynagier, A.; Guillaume, B.; Guzmán, F.; Harrison, I.; Hewitson, M.; Hollington, D.; Hough, J.; Hoyland, D.; Hueller, M.; Huesler, J.; Jeannin, O.; Jennrich, O.; Jetzer, P.; Johlander, B.; Killow, C.; Llamas, X.; Lloro, I.; Lobo, A.; Maarschalkerweerd, R.; Madden, S.; Mance, D.; Mateos, I.; McNamara, P. W.; Mendes, J.; Mitchell, E.; Nicolini, D.; Nicolodi, D.; Pedersen, F.; Perreur-Lloyd, M.; Perreca, A.; Plagnol, E.; Prat, P.; Racca, G. D.; Rais, B.; Ramos-Castro, J.; Reiche, J.; Romera Perez, J. A.; Robertson, D.; Rozemeijer, H.; Sanjuan, J.; Schulte, M.; Shaul, D.; Stagnaro, L.; Strandmoe, S.; Sumner, T. J.; Taylor, A.; Texier, D.; Trenkel, C.; Tombolato, D.; Vitale, S.; Wanner, G.; Ward, H.; Waschke, S.; Wass, P.; Weber, W. J.; Zweifel, P.

2011-05-01

199

Growth Cone Pathfinding: a competition between deterministic and stochastic events  

PubMed Central

Background Growth cone migratory patterns show evidence of both deterministic and stochastic search modes. Results We quantitatively examine how these two different migration modes affect the growth cone's pathfinding response, by simulating growth cone contact with a repulsive cue and measuring the resultant turn angle. We develop a dimensionless number, we call the determinism ratio ?, to define the ratio of deterministic to stochastic influences driving the growth cone's migration in response to an external guidance cue. We find that the growth cone can exhibit three distinct types of turning behaviors depending on the magnitude of ?. Conclusions We conclude, within the context of these in silico studies, that only when deterministic and stochastic migration factors are in balance (i.e. ? ~ 1) can the growth cone respond constructively to guidance cues.

Maskery, Susan M; Buettner, Helen M; Shinbrot, Troy

2004-01-01

200

Structural analyses of the JPL Mars Pathfinder impact  

SciTech Connect

The purpose of this paper is to demonstrate that finite element analysis can be used in the design process for high performance fabric structures. These structures exhibit extreme geometric nonlinearity; specifically, the contact and interaction of fabric surfaces with the large deformation which necessarily results from membrane structures introduces great complexity to analyses of this type. All of these features are demonstrated here in the analysis of the Jet Propulsion Laboratory (JPL) Mars Pathfinder impact onto Mars. This lander system uses airbags to envelope the lander experiment package, protecting it with large deformation upon contact. Results from the analysis show the stress in the fabric airbags, forces in the internal tendon support system, forces in the latches and hinges which allow the lander to deploy after impact, and deceleration of the lander components. All of these results provide the JPL engineers with design guidance for the success of this novel lander system.

Gwinn, K.W. [Sandia National Labs., Albuquerque, NM (United States). Material and Structural Mechanics Dept.

1994-12-31

201

Aeolian features and processes at the Mars Pathfinder landing site  

USGS Publications Warehouse

The Mars Pathfinder landing site contains abundant features attributed to aeolian, or wind, processes. These include wind tails, drift deposits, duneforms of various types, ripplelike features, and ventifacts (the first clearly seen on Mars). Many of these features are consistant with formation involving sand-size particles. Although some features, such as dunes, could develop from saltating sand-size aggregates of finer grains, the discovery of ventifact flutes cut in rocks strongly suggests that at least some of the grains are crystalline, rather than aggregates. Excluding the ventifacts, the orientations of the wind-related features correlate well with the orientations of bright wind steaks seen on Viking Orbiter images in the general area. They also correlate with wind direction predictions from the NASA-Ames General Circulation Model (GCM) which show that the strongest winds in the area occur in the northern hemisphere winter and are directed toward 209°. Copyright 1999 by the American Geophysical Union.

Greeley, Ronald; Kraft, Michael; Sullivan, Robert; Wilson, Gregory; Bridges, Nathan; Herkenhoff, Ken; Kuzmin, Ruslan O.; Malin, Michael; Ward, Wes

1999-01-01

202

Structural analyses of the JPL Mars Pathfinder impact  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to demonstrate that finite element analysis can be used in the design process for high performance fabric structures. These structures exhibit extreme geometric nonlinearity; specifically, the contact and interaction of fabric surfaces with the large deformation which necessarily results from membrane structures introduces great complexity to analyses of this type. All of these features are demonstrated here in the analysis of the Jet Propulsion Laboratory (JPL) Mars Pathfinder impact onto Mars. This lander system uses airbags to envelope the lander experiment package, protecting it with large deformation upon contact. Results from the analysis show the stress in the fabric airbags, forces in the internal tendon support system, forces in the latches and hinges which allow the lander to deploy after impact, and deceleration of the lander components. All of these results provide the JPL engineers with design guidance for the success of this novel lander system.

Gwinn, Kenneth W.

203

Soil-like deposits observed by Sojourner, the Pathfinder rover  

NASA Astrophysics Data System (ADS)

Most of the soil-like materials at the Pathfinder landing site behave like moderately dense soils on Earth with friction angles near 34°-39° and are called cloddy deposits. Cloddy deposits appear to be poorly sorted with dust-sized to granule-sized mineral or rock grains; they may contain pebbles, small rock fragments, and clods. Thin deposits of porous, compressible drifts with friction angles near 26°-28° are also present. Drifts are fine grained. Cohesions of both types of deposits are small. There may be indurated soil-like deposits and/or coated or crusted rocks. Cloddy deposits may be fluvial sediments of the Ares-Tiu floods, but other origins, such as ejecta from nearby impact craters, should be considered. Drifts are probably dusts that settled from the Martian atmosphere. Remote-sensing signatures of the deposits inferred from rover observations are consistent with those observed from orbit and Earth.

Moore, Henry J.; Bickler, Donald B.; Crisp, Joy A.; Eisen, Howard J.; Gensler, Jeffrey A.; Haldemann, Albert F. C.; Matijevic, Jacob R.; Reid, Lisa K.; Pavlics, Ferenc

1999-04-01

204

Measuring coral reef community metabolism using new benthic chamber technology  

USGS Publications Warehouse

Accurate measurement of coral reef community metabolism is a necessity for process monitoring and in situ experimentation on coral reef health. Traditional methodologies used for these measurements are effective but limited by location and scale constraints. We present field trial results for a new benthic chamber system called the Submersible Habitat for Analyzing Reef Quality (SHARQ). This large, portable incubation system enables in situ measurement and experimentation on community- scale metabolism. Rates of photosynthesis, respiration, and calcification were measured using the SHARQ for a variety of coral reef substrate types on the reef flat of South Molokai, Hawaii, and in Biscayne National Park, Florida. Values for daily gross production, 24-h respiration, and net calcification ranged from 0.26 to 6.45 g O2 m-2 day-1, 1.96 to 8.10 g O2 m-2 24 h-1, and 0.02 to 2.0 g CaCO3 m -2 day-1, respectively, for all substrate types. Field trials indicate that the SHARQ incubation chamber is an effective tool for in situ isolation of a water mass over a variety of benthic substrate types for process monitoring, experimentation, and other applications.

Yates, K. K.; Halley, R. B.

2003-01-01

205

Herbicides: a new threat to the Great Barrier Reef.  

PubMed

The runoff of pesticides (insecticides, herbicides and fungicides) from agricultural lands is a key concern for the health of the iconic Great Barrier Reef, Australia. Relatively low levels of herbicide residues can reduce the productivity of marine plants and corals. However, the risk of these residues to Great Barrier Reef ecosystems has been poorly quantified due to a lack of large-scale datasets. Here we present results of a study tracing pesticide residues from rivers and creeks in three catchment regions to the adjacent marine environment. Several pesticides (mainly herbicides) were detected in both freshwater and coastal marine waters and were attributed to specific land uses in the catchment. Elevated herbicide concentrations were particularly associated with sugar cane cultivation in the adjacent catchment. We demonstrate that herbicides reach the Great Barrier Reef lagoon and may disturb sensitive marine ecosystems already affected by other pressures such as climate change. PMID:19349104

Lewis, Stephen E; Brodie, Jon E; Bainbridge, Zoë T; Rohde, Ken W; Davis, Aaron M; Masters, Bronwyn L; Maughan, Mirjam; Devlin, Michelle J; Mueller, Jochen F; Schaffelke, Britta

2009-04-05

206

Upper Permian Capitan Reef  

SciTech Connect

A depositional and diagentic model for the Capitan reef complex (Late Permian, Guadalupian age) has evolved during more than 50 years of outcrop studies in the Guadalupe Mountains of west Texas and New Mexico. The model relates the shelf margin (Capitain Limestone) with equivalent shelf (in ascending order, Seven Rivers, Yates, and Tansill Formations) and basin (Bell Canyon Formation) strata. It has proved to be important in relating hydrocarbon distribution in shelf and basin strata in the Permian basin and has been important as an analog in numerous other basins. Detailed study of the northern rim of the Delaware basin, centering on a 4,800-ft core, has caused us to reevaluate the outcrop-defined depositional model for the Capitan shelf margin along the following themes. Geologic evolution. Progradation of the margin was not uniform throughout deposition of the Capitan as is portrayed in most reconstructions. Outcrop mapping and log correlations, in fact, show that 75% of the total basinward progradation of the Capitan occurred during deposition of the Seven Rivers Formation. This maximum progradation corresponds to back-reef carbonates largely devoid of siliciclastics, thick carbonate debris beds on the slope and basin edge, and thick siliclastics deposited in the basin. Depositional facies and diagenesis. The pisolithic shoal complex, the predominant feature marking the highest part of the shelf margin, was more laterally extensive than known from outcrop.

Harris, P.M.; Garber, R.A.; Grover, G.A.

1988-01-01

207

Expeditions in Conservation: Mesoamerican Reef  

NSDL National Science Digital Library

The World Wildlife Fund (WWF) recently completed this expedition of the largest coral reef system in the Atlantic Ocean and has provided an opportunity for Web users to share some of what they experienced. Visitors can view spectacular photos and videos to learn about the reef and the creatures that reside there, as well as read the daily reports of the expedition. The site offers much more in terms of learning about coral reefs, the people who study them, and the threats that face these unique ecosystems.

1969-12-31

208

NOAA's hydrolab conducts reef studies  

NASA Astrophysics Data System (ADS)

This summer, scuba-diving scientists operating from Hydrolab, NOAA's undersea laboratory, are carrying out four experiments aimed at producing better management of coral reefs and their fishery resources. Hydrolab is located at a depth of 50 feet, near the mouth of the Salt River, off St. Croix, U.S. Virgin Islands. The lab houses four scientists for up to 2 weeks at a time, permitting them to swim out into the water to conduct research. The projects make use of both the natural coral reef near Hydrolab and the nearby artificial reef constructed for comparison studies.

209

Predicting the impact of present and future human land-use on the Great Barrier Reef  

NASA Astrophysics Data System (ADS)

An ecohydrologic model, verified against field data, suggests that land-use has contributed to degradation of the health of the Great Barrier Reef and to an increased frequency and intensity of crown-of-thorns starfish infestations. The model also predicts that the health of the Great Barrier Reef will significantly worsen by the year 2050 as a result of global warming. However, the model also suggests that much-improved land-use practices will enable some regions of the Great Barrier Reef to recover, even with global warming. Finally, the model suggests that, if global warming proceeds unchecked, biological adaptation is necessary to avoid a collapse of the Great Barrier Reef health by the year 2100.

Wolanski, Eric; de'Ath, Glenn

2005-08-01

210

A critical examination of stoichiometric and path-finding approaches to metabolic pathways.  

PubMed

Advances in the field of genomics have enabled computational analysis of metabolic pathways at the genome scale. Singular attention has been devoted in the literature to stoichiometric approaches, and path-finding approaches, to metabolic pathways. Stoichiometric approaches make use of reaction stoichiometry when trying to determine metabolic pathways. Stoichiometric approaches involve elementary flux modes and extreme pathways. In contrast, path-finding approaches propose an alternative view based on graph theory in which reaction stoichiometry is not considered. Path-finding approaches use shortest path and k-shortest path concepts. In this article we give a critical overview of the theory, applications and key research challenges of stoichiometric and path-finding approaches to metabolic pathways. PMID:18436574

Planes, Francisco J; Beasley, John E

2008-04-24

211

Role of Shipyard Pollutants in Structuring Coral Reef Microbial Communities: Monitoring Environmental Change and the Potential Causes of Coral Disease.  

National Technical Information Service (NTIS)

The US Navy operates military bases in tropical and sub-tropical seas that are surrounded by coral reefs. Therefore, the goal of this work has been to develop methods for long-term monitoring of the effects of naval activity on the health of these reef ec...

B. W. Fouke

2006-01-01

212

Ecology of the south Florida coral reefs: a community profile  

SciTech Connect

An overview of coral reef research in southern Florida is provided as a prelude to a genuine description of the coral reef ecosystem in the Florida Keys and surrounding environments. Coral reef community types, reef benthos, plankton and reef fish are given specific treatment. Coral reef ecology and management are described. 27 figs., 31 tabs.

Jaap, W.C.

1984-08-01

213

Fish assemblages on estuarine artificial reefs: natural rocky-reef mimics or discrete assemblages?  

PubMed

If the primary goal of artificial reef construction is the creation of additional reef habitat that is comparable to adjacent natural rocky-reef, then performance should be evaluated using simultaneous comparisons with adjacent natural habitats. Using baited remote underwater video (BRUV) fish assemblages on purpose-built estuarine artificial reefs and adjacent natural rocky-reef and sand-flat were assessed 18 months post-deployment in three south-east Australian estuaries. Fish abundance, species richness and diversity were found to be greater on the artificial reefs than on either naturally occurring reef or sand-flat in all estuaries. Comparisons within each estuary identified significant differences in the species composition between the artificial and natural rocky-reefs. The artificial reef assemblage was dominated by sparid species including Acanthopagrus australis and Rhabdosargus sarba. The preference for a range of habitats by theses sparid species is evident by their detection on sand-flat, natural rocky reef and artificial reef habitats. The fish assemblage identified on the artificial reefs remained distinct from the adjacent rocky-reef, comprising a range of species drawn from naturally occurring rocky-reef and sand-flat. In addition, some mid-water schooling species including Trachurus novaezelandiae and Pseudocaranx georgianus were only identified on the artificial reef community; presumably as result of the reef's isolated location in open-water. We concluded that estuarine artificial reef assemblages are likely to differ significantly from adjacent rocky-reef, potentially as a result of physical factors such as reef isolation, coupled with species specific behavioural traits such as the ability of some species to traverse large sand flats in order to locate reef structure, and feeding preferences. Artificial reefs should not be viewed as direct surrogates for natural reef. The assemblages are likely to remain distinct from naturally occurring habitat comprised of species that reside on a range of adjacent natural habitats. PMID:23755106

Folpp, Heath; Lowry, Michael; Gregson, Marcus; Suthers, Iain M

2013-06-03

214

Fish Assemblages on Estuarine Artificial Reefs: Natural Rocky-Reef Mimics or Discrete Assemblages?  

PubMed Central

If the primary goal of artificial reef construction is the creation of additional reef habitat that is comparable to adjacent natural rocky-reef, then performance should be evaluated using simultaneous comparisons with adjacent natural habitats. Using baited remote underwater video (BRUV) fish assemblages on purpose-built estuarine artificial reefs and adjacent natural rocky-reef and sand-flat were assessed 18 months post-deployment in three south-east Australian estuaries. Fish abundance, species richness and diversity were found to be greater on the artificial reefs than on either naturally occurring reef or sand-flat in all estuaries. Comparisons within each estuary identified significant differences in the species composition between the artificial and natural rocky-reefs. The artificial reef assemblage was dominated by sparid species including Acanthopagrus australis and Rhabdosargus sarba. The preference for a range of habitats by theses sparid species is evident by their detection on sand-flat, natural rocky reef and artificial reef habitats. The fish assemblage identified on the artificial reefs remained distinct from the adjacent rocky-reef, comprising a range of species drawn from naturally occurring rocky-reef and sand-flat. In addition, some mid-water schooling species including Trachurus novaezelandiae and Pseudocaranx georgianus were only identified on the artificial reef community; presumably as result of the reef's isolated location in open-water. We concluded that estuarine artificial reef assemblages are likely to differ significantly from adjacent rocky-reef, potentially as a result of physical factors such as reef isolation, coupled with species specific behavioural traits such as the ability of some species to traverse large sand flats in order to locate reef structure, and feeding preferences. Artificial reefs should not be viewed as direct surrogates for natural reef. The assemblages are likely to remain distinct from naturally occurring habitat comprised of species that reside on a range of adjacent natural habitats.

Folpp, Heath; Lowry, Michael; Gregson, Marcus; Suthers, Iain M.

2013-01-01

215

Effectiveness of benthic foraminiferal and coral assemblages as water quality indicators on inshore reefs of the Great Barrier Reef, Australia  

NASA Astrophysics Data System (ADS)

Although the debate about coral reef decline focuses on global disturbances (e.g., increasing temperatures and acidification), local stressors (nutrient runoff and overfishing) continue to affect reef health and resilience. The effectiveness of foraminiferal and hard-coral assemblages as indicators of changes in water quality was assessed on 27 inshore reefs along the Great Barrier Reef. Environmental variables (i.e., several water quality and sediment parameters) and the composition of both benthic foraminiferal and hard-coral assemblages differed significantly between four regions (Whitsunday, Burdekin, Fitzroy, and the Wet Tropics). Grain size and organic carbon and nitrogen content of sediments, and a composite water column parameter (based on turbidity and concentrations of particulate matter) explained a significant amount of variation in the data (tested by redundancy analyses) in both assemblages. Heterotrophic species of foraminifera were dominant in sediments with high organic content and in localities with low light availability, whereas symbiont-bearing mixotrophic species were dominant elsewhere. A similar suite of parameters explained 89% of the variation in the FORAM index (a Caribbean coral reef health indicator) and 61% in foraminiferal species richness. Coral richness was not related to environmental setting. Coral assemblages varied in response to environmental variables, but were strongly shaped by acute disturbances (e.g., cyclones, Acanthaster planci outbreaks, and bleaching), thus different coral assemblages may be found at sites with the same environmental conditions. Disturbances also affect foraminiferal assemblages, but they appeared to recover more rapidly than corals. Foraminiferal assemblages are effective bioindicators of turbidity/light regimes and organic enrichment of sediments on coral reefs.

Uthicke, S.; Thompson, A.; Schaffelke, B.

2010-03-01

216

Commencement on a Coral Reef  

ERIC Educational Resources Information Center

|Describes an environmental program in which sixteen students and three biology teachers from Northfield Mount Hermon School in Massachusetts spent two weeks examining the ecology of a Caribbean reef.. (JR)|

Webster, Steven K.

1973-01-01

217

Biological destruction of coral reefs  

NASA Astrophysics Data System (ADS)

The major agents of biological destruction of coral reefs can be divided into grazers, etchers and borers. Each of these groups is reviewed on a world wide basis, together with the mechanisms by which they destroy the coral substrate. Rates of bioerosion attributed to major agents of grazers, etchers and borers are given, together with limitations of some of the measurements. Recent work is highlighting the variability in rates of bioerosion both over time and space. Factors which may be responsible for this variability are discussed. Bioerosion is a major factor influencing reef morphology and the ways in which this is achieved is discussed in some detail. Although the review concentrates mainly on present day reefs, some attempt is made to consider the impact of bioerosion on older reefs.

Hutchings, P. A.

1986-05-01

218

Artificial Reefs and Ocean Dumping.  

ERIC Educational Resources Information Center

|Activities and instructional strategies for two multigrade lessons are provided. Activity objectives include describing an artificial reef (such as a sunken ocean liner) as an ecosystem, knowing animal types in the ecosystem, and describing a food web. (JN)|

Glueck, Richard D.

1983-01-01

219

Reef Bioerosion: Agents and Processes  

Microsoft Academic Search

\\u000a Coral reef maintenance depends on the balance between constructive and destructive forces. Constructive forces are mainly\\u000a calcification and growth of corals and encrusting coralline algae. Destructive forces comprise physical, chemical, and biological\\u000a erosion. Bioerosion is considered as the main force of reef degradation because physical erosion (storms) is temporary and\\u000a localized, and chemical erosion is considered as negligible due to

Aline Tribollet; Stjepko Golubic

220

Florida Keys NMS: Coral Reefs  

NSDL National Science Digital Library

Florida Keys National Marine Sanctuary's page with information on coral reefs and links to information on research, restoration and monitoring. Wealth of information on the protection of Florida's coral reefs and the Florida Keys as a whole. Includes an in-class activity for grades K-5, as well as information on a Keys field experience and teacher workshops. Information on safe diving and snorkeling. Education materials available for purchase, including the Seagrass Toolbox.

2011-11-04

221

The impacts of tourism on coral reef conservation awareness and support in coastal communities in Belize  

NASA Astrophysics Data System (ADS)

Marine recreational tourism is one of a number of threats to the Belize Barrier Reef but, conversely, represents both a motivation and source of resources for its conservation. The growth of tourism in Belize has resulted in the fact that many coastal communities are in varying stages of a socio-economic shift from dependence on fishing to dependence on tourism. In a nation becoming increasingly dependent on the health of its coral reef ecosystems for economic prosperity, a shift from extractive uses to their preservation is both necessary and logical. Through examining local perception data in five coastal communities in Belize, each attracting different levels of coral reef related tourism, this analysis is intended to explore the relationship between tourism development and local coral reef conservation awareness and support. The results of the analysis show a positive correlation between tourism development and coral reef conservation awareness and support in the study communities. The results also show a positive correlation between tourism development and local perceptions of quality of life, a trend that is most likely the source of the observed relationship between tourism and conservation. The study concludes that, because the observed relationship may be dependent on continued benefits from tourism as opposed to a perceived crisis in coral reef health, Belize must pay close attention to tourism impacts in the future. Failure to do this could result in a destructive feedback loop that would contribute to the degradation of the reef and, ultimately, Belize’s diminished competitiveness in the ecotourism market.

Diedrich, A.

2007-12-01

222

Distribution, abundance, and substrate preferences of demersal reef zooplankton at Lizard Island Lagoon, Great Barrier Reef  

Microsoft Academic Search

Demersal zooplankton, those plankton which hide within reef sediments during the day but emerge to swim freely over the reef at night, were sampled quantitatively using emergence traps planced over the substrate at Lizard Island Lagoon, Great Barrier Reef. Densities of zooplankton emerging at night from 6 substrate types (fine, medium, and coarse sand, rubble, living coral and reef rock)

A. L. Alldredge; J. M. King

1977-01-01

223

Coral reef development under naturally turbid conditions: fringing reefs near Broad Sound, Australia  

Microsoft Academic Search

Reef coring and NOAA\\/AVHRR imagery were used to examine differences in reef colonisation and accumulation across a gradient of increasing tidal range and turbidity. AVHRR channel-1 reflectance, which was strongly correlated with suspended sediment concentration (SSC), demonstrated that SSC is due to tidal resuspension of sediments, and increases with increasing tidal range. Underwater surveys and reef coring revealed that reef

J. A. Kleypas

1996-01-01

224

Benthic microalgae in coral reef sediments of the southern Great Barrier Reef, Australia  

Microsoft Academic Search

The abundance and productivity of benthic microalgae in coral reef sediments are poorly known compared with other, more conspicuous (e.g. coral zooxanthellae, macroalgae) primary producers of coral reef habitats. A survey of the distribution, biomass, and productivity of benthic microalgae on a platform reef flat and in a cross-shelf transect in the southern Great Barrier Reef indicated that benthic microalgae

C. A. Heil; K. Chaston; A. Jones; P. Bird; B. Longstaff; S. Costanzo; W. C. Dennison

2004-01-01

225

Terrigenous sediments as influences upon Holocene nearshore coral reefs, central Great Barrier Reef, Australia  

Microsoft Academic Search

Sedimentary studies of inner shelf reefs on the Great Barrier Reef shelf increasingly reveal evidence for coral growth in turbid, shallow coastal environments, where coral survival is aided by prevailing hydrodynamic and sedimentological conditions. New models of coral reef growth on the Great Barrier Reef are needed which explicitly include the role of terrigenous sediments in influencing sites of potential

P. Larcombe; K. J. Woolfe

1999-01-01

226

Coral-reef hydrology: field studies of water movement within a barrier reef  

Microsoft Academic Search

Water movement through the framework of Davies Reef, a coral reef in the central Australian Great Barrier Reef, was studied using field and laboratory determinations of permeability, tide gauge measurements of water levels, dye tracers, and pore water chemistry. Flow is driven by current, wind-induced, or tide-induced water level differences which were shown to occur between reef front and lagoon.

J. A. Oberdorfer; R. W. Buddemeier

1986-01-01

227

Early Development of Pendelton Artificial Reef.  

National Technical Information Service (NTIS)

An artificial reef was constructed of 10,000 tons of quarry rock in Southern California offshore of Camp Pendleton. Management techniques have included transplanting giant kelp to accelerate and direct ecological succession changes on the reef.

A. Grover H. A. Togstad J. J. Grant K. C. Wilson

1982-01-01

228

The dynamics of benthic microbial communities at Davies Reef, central Great Barrier Reef  

Microsoft Academic Search

The dynamics of benthic microbial communities were examined within different functional zones (reef crest, reef flat, lagoon) of Davies Reef, central Great Barrier Reef, in winter. Bacterial numbers did not change significantly across the reef with a mean abundance \\u000a$$(\\\\bar x{\\\\text{ }} \\\\pm {\\\\text{ 1 SE)}}$$\\u000a of 1.3 (±0.6) x 109 cells g-1 DW of sediment. Bacterial production, measured as

L. A. Hansen; D. M. Alongi; D. J. W. Moriarty; P. C. Pollard

1987-01-01

229

Coral Reef Fishes: Opportunities, Challenges and Concerns  

Microsoft Academic Search

\\u000a Coral reef fishes represent superb models for test of biological theory in field or laboratory. Nonetheless, our knowledge\\u000a comes from few locations, few biological disciplines, and few of the more than 70 families of fishes occupying coral reefs.\\u000a Most reef fishes exhibit complex life histories involving distinctive pelagic larval stages, ecological and structural changes\\u000a associated with settling on reefs, and

W. Linn Montgomery

230

Mineralogy, composition, and alteration of Mars Pathfinder rocks and soils: Evidence from multispectral, elemental, and magnetic data on terrestrial analogue, SNC meteorite, and Pathfinder samples  

Microsoft Academic Search

Major element, multispectral, and magnetic properties data were obtained at Ares Vallis during the Mars Pathfinder mission. To understand the compositional, mineralogical, and process implications of these data, we obtained major element, mineralogical, and magnetic data for well-crystalline and nanophase ferric minerals, terrestrial analogue samples with known geologic context, and SNC meteorites. Analogue samples include unaltered, palagonitic, and sulfatetic tephra

Richard V. Morris; Tad D. Shelfer; Andreas C. Scheinost; Nancy W. Hinman; George Furniss; Janice L. Bishop; Douglas W. Ming; Carlton C. Allen; Daniel T. Britt

2000-01-01

231

40 CFR 230.44 - Coral reefs.  

Code of Federal Regulations, 2010 CFR

... 24 2009-07-01 2009-07-01 false Coral reefs. 230.44 Section 230.44 Protection of...Impacts on Special Aquatic Sites § 230.44 Coral reefs. (a) Coral reefs consist of the skeletal deposit, usually...

2009-07-01

232

40 CFR 230.44 - Coral reefs.  

Code of Federal Regulations, 2010 CFR

... 24 2010-07-01 2010-07-01 false Coral reefs. 230.44 Section 230.44 Protection of...Impacts on Special Aquatic Sites § 230.44 Coral reefs. (a) Coral reefs consist of the skeletal deposit, usually...

2010-07-01

233

Coral Reefs and Their Management in Tanzania  

Microsoft Academic Search

Coral reefs are very important in Tanzania, both ecologically and socio-economically, as major fishing grounds and tourist attractions. Numerous fringing and patch reefs are located along about two-thirds of Tanzania's coastline. These reefs have been partially to severely degraded by human (primarily destructive fishing practices) and natural (particularly coral bleaching) causes. These immediate human causes have been brought about by

Greg M. Wagner

234

Silurian pinnacle reefs of the Canadian Arctic  

Microsoft Academic Search

Pinnacle reefs are commonly an attractive target for oil exploration because they are usually porous carbonate bodies entombed in impervious, deep-water shales that provide both the source and the seal for hydrocarbons. Silurian pinnacle reefs, the first described in the Canadian Arctic Archipelago, are exposed on Ellesmere and Devon Islands. Two main reef trends occur, one of early middle Llandovery

T. A. De Freitas; O. A. Dixon; U. Mayr

1993-01-01

235

The Pros and Cons of Artificial Reefs  

NSDL National Science Digital Library

This lesson plan asks students to consider whether artificial reefs (human-made objects in the ocean or sea) are good for marine ecosystems. Students will look at pictures of artificial reefs and read articles describing the pros and cons of these structures. They will conclude by writing paragraphs explaining whether they think a new artificial reef should be created in Florida waters.

236

The Biosphere 2 coral reef biome  

Microsoft Academic Search

The Biosphere 2 coral reef biome is a large tank of living coral reef organisms (water volume of 2650 m3, water surface area of 711 m2 and 590 m2 of reef benthos). The water of the biome is characteristically very low in dissolved nutrients and phytoplankton. The present community of organisms is largely comprised of macroalgae, including 11 genera of

M. J. Atkinson; H. Barnett; H. Aceves; C. Langdon; S. J. Carpenter; T. McConnaughey; E. Hochberg; M. Smith; B. D. V. Marino

1999-01-01

237

Slope Morphology of Twin Peaks, Mars Pathfinder Landing Site  

NASA Astrophysics Data System (ADS)

Development of slope form over time has long been a concern of geomorphologists, although recently this concern has been moved to slope processes rather than form. There are two basic approaches. The first is theoretical, involving modeling of different types and rates of processes, and calculation of results in terms of slope evolution over time. Comparisons with real-life slopes can follow this approach [1], [2]. The second, inductive, approach involves field measurements to test ideas about slope evolution starting from the assumption that observed slopes represent different stages of an essentially similar evolution [3]. Space is substituted for time, and a number of slopes, assumed to be of increasing age, are measured and placed in an evolutionary sequence (e.g. [4], [5], [6]). [5] showed that slope angles are modally distributed, with the modal angles controlled by the materials (regolith) of which the slopes are formed, and by the processes operating on them. Data can be obtained directly from field work or from digital elevation models (DEM) derived from remote sensing investigations [7]. DEMs are particularly useful to study inaccessible planets, such as Mars, where on site observations are restricted to only a few landing sites. Here we present a study of slopes on the Twin Peaks, two small hills located 780 m north and 910 m south of the Mars Pathfinder landing site at the mouth of the Ares and Tiu flood channels. The presence of streamlined hills, jumbled surfaces and conglomerates suggested the region was modified by massive flooding 1.8 - 3.5 billion years ago [8], [9]. The streamlined forms and terraces of the Twin Peaks were taken to indicate catastrophic flood conditions that were believed to be prevalent in the area [8]. It was also suggested that the northernmost peak was topped by floodwater, causing its flatter appearance. Other researchers postulated alternative geomorphological origins for the features observed at the Pathfinder landing site. Processes such as ice flow or deposition were proposed as being the principal cause of most of observed features, by analogy with similar features observed on Earth [10]. Here we propose that the slopes on the Twin Peaks may provide an indication of the processes that shaped them after they were formed. This work shows the results of a detailed morphometric analysis of slopes on the southernmost peak, conducted to gain a greater understanding of past and present slope processes at work at the Pathfinder landing site. The southern Twin Peak is a conical hill rising 38 m above the local terrain. A portion of the Pathfinder super panorama was used to analyse the hill-slope morphology. The camera horizon was used as a baseline and all slope angles were measured from this. The hill comprises four separate regions including the top of the hill, which is convex in shape. The convex nature of the hilltop is a common if not ubiquitous feature of hills regardless of their origin. It is related to the creep processes that frequently dominate the tops of hill slopes. In this case it was probably caused by heating and cooling during the Martian diurnal cycle, by the action of soil water, or a combination of both. All slope sections were observed to be similar in length. The slopes nearest the hill top measure 21? and 22.5? respectively on the north and south sides of the Southern Twin Peak. Mid way down the hill the next sequence of slopes have north and south angles of 9? and 15? respectively. Shallow end-slopes measure 4? and 5? north and south respectively. Similarity of slope angles and lengths indicates symmetry, suggesting that the rocks are the same all around the hill. Our analysis suggests that slope angles are controlled by a combination of the materials of which they are formed and the processes that are operating on them. Their primarily symmetrical outlook indicates no structural control, suggesting that the hill is formed by flat-lying or massive homogeneous rocks. This being the case, slope morphology results from shallow processes related to mass was

Hobbs, Steven; Paine, Colin; Clarke, Jon; Caprarelli, Graziella

2010-05-01

238

Science with the Australian Square Kilometre Array Pathfinder  

NASA Astrophysics Data System (ADS)

The future of centimetre and metre-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries that will be 50 times more sensitive than any existing radio facility. Most of the key science for the SKA will be addressed through large-area imaging of the Universe at frequencies from a few hundred MHz to a few GHz. The Australian SKA Pathfinder (ASKAP) is a technology demonstrator aimed in the mid-frequency range, and achieves instantaneous wide-area imaging through the development and deployment of phased-array feed systems on parabolic reflectors. The large field-of-view makes ASKAP an unprecedented synoptic telescope that will make substantial advances in SKA key science. ASKAP will be located at the Murchison Radio Observatory in inland Western Australia, one of the most radio-quiet locations on the Earth and one of two sites selected by the international community as a potential location for the SKA. In this paper, we outline an ambitious science program for ASKAP, examining key science such as understanding the evolution, formation and population of galaxies including our own, understanding the magnetic Universe, revealing the transient radio sky and searching for gravitational waves.

Johnston, S.; Bailes, M.; Bartel, N.; Baugh, C.; Bietenholz, M.; Blake, C.; Braun, R.; Brown, J.; Chatterjee, S.; Darling, J.; Deller, A.; Dodson, R.; Edwards, P. G.; Ekers, R.; Ellingsen, S.; Feain, I.; Gaensler, B. M.; Haverkorn, M.; Hobbs, G.; Hopkins, A.; Jackson, C.; James, C.; Joncas, G.; Kaspi, V.; Kilborn, V.; Koribalski, B.; Kothes, R.; Landecker, T. L.; Lenc, E.; Lovell, J.; Macquart, J.-P.; Manchester, R.; Matthews, D.; McClure-Griffiths, N. M.; Norris, R.; Pen, U.-L.; Phillips, C.; Power, C.; Protheroe, R.; Sadler, E.; Schmidt, B.; Stairs, I.; Staveley-Smith, L.; Stil, J.; Taylor, R.; Tingay, S.; Tzioumis, A.; Walker, M.; Wall, J.; Wolleben, M.

2007-12-01

239

Science with ASKAP. The Australian square-kilometre-array pathfinder  

NASA Astrophysics Data System (ADS)

The future of cm and m-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries. The SKA will be 50 times more sensitive than any existing radio facility. A majority of the key science for the SKA will be addressed through large-area imaging of the Universe at frequencies from 300 MHz to a few GHz. The Australian SKA Pathfinder (ASKAP) is aimed squarely in this frequency range, and achieves instantaneous wide-area imaging through the development and deployment of phase-array feed systems on parabolic reflectors. This large field-of-view makes ASKAP an unprecedented synoptic telescope poised to achieve substantial advances in SKA key science. The central core of ASKAP will be located at the Murchison Radio Observatory in inland Western Australia, one of the most radio-quiet locations on the Earth and one of the sites selected by the international community as a potential location for the SKA. Following an introductory description of ASKAP, this document contains 7 chapters describing specific science programmes for ASKAP. In summary, the goals of these programmes are as follows: The detection of a million galaxies in atomic hydrogen emission across 75% of the sky out to a redshift of 0.2 to understand galaxy formation and gas evolution in the nearby Universe.

Johnston, S.; Taylor, R.; Bailes, M.; Bartel, N.; Baugh, C.; Bietenholz, M.; Blake, C.; Braun, R.; Brown, J.; Chatterjee, S.; Darling, J.; Deller, A.; Dodson, R.; Edwards, P.; Ekers, R.; Ellingsen, S.; Feain, I.; Gaensler, B.; Haverkorn, M.; Hobbs, G.; Hopkins, A.; Jackson, C.; James, C.; Joncas, G.; Kaspi, V.; Kilborn, V.; Koribalski, B.; Kothes, R.; Landecker, T.; Lenc, A.; Lovell, J.; Macquart, J.-P.; Manchester, R.; Matthews, D.; McClure-Griffiths, N.; Norris, R.; Pen, U.-L.; Phillips, C.; Power, C.; Protheroe, R.; Sadler, E.; Schmidt, B.; Stairs, I.; Staveley-Smith, L.; Stil, J.; Tingay, S.; Tzioumis, A.; Walker, M.; Wall, J.; Wolleben, M.

2008-12-01

240

PathFinder Science: Keeping an Eye on Ozone  

NSDL National Science Digital Library

This site offers information and research projects that engage students in learning about ground level ozone. As part of the Pathfinder Science Collaborative Research program, students conduct scientific research on real-world topics to understand the process of science. They then submit their data so that other students and scientists around the world gain a better understanding of the issues and drive further research. Other topics include monitoring monarch butterflies, lichens, and greenhouse gases. In this forum, students determine the level of tropospheric ozone in their area and the impact on organisms in the environment, such as the milkweed plant. Background information, instructions for making ozone testing paper, and a protocol for measuring the impact of ozone on milkweed plant are provided. After collecting data, students submit it electronically and then access other students' data to develop and answer further research questions. The site also offers information on formulating questions, research methods, and data analysis along with the process and values that underlie scientific research.

241

Experiences with operations and autonomy of the Mars Pathfinder Microrover.  

NASA Astrophysics Data System (ADS)

The Microrover Flight Experiment (MFEX) is a NASA OACT (Office of Advanced Concepts and Technology) flight experiment which, integrated with the Mars Pathfinder (MPF) lander and spacecraft system, landed on Mars on July 4, 1997. In the succeeding 30 sols (1 sol = 1 Martian day), the Sojourner microrover accomplished all of its primary and extended mission objectives. After completion of the originally planned extended mission, MFEX continued to conduct a series of technology experiments, deploy its alpha proton X-ray spectrometer (APXS) on rocks and soil, and image both terrain features and the lander. This mission was conducted under the constraints of a once-per-sol opportunity for command and telemetry transmissions between the lander and Earth operators. As such, the MFEX rover was required to carry out its mission, including terrain navigation and contingency response, under supervised autonomous control. For example, goal locations were specified daily by human operators; the rover then safely traversed to these locations. During traverses, the rover autonomously detected and avoided rock, slope, and drop-off hazards, changing its path as needed before turning back towards its goal. This capability to operate in an unmodeled environment, choosing actions in response to sensor input to accomplish requested objectives, is unique among robotic space missions to date.

Mishkin, A. H.; Morrison, J. C.; Nguyen, T. T.; Stone, H. W.; Cooper, B. K.; Wilcox, B. H.

242

Antenna Deployment for a Pathfinder Lunar Radio Observatory  

NASA Astrophysics Data System (ADS)

A first step in the development of a large radio observatory on the moon for cosmological or other astrophysical and planetary goals is to deploy a few antennas as a pathfinder mission. In this presentation, we describe a mechanism being developed to deploy such antennas from a small craft, such as a Google Lunar X-prize lander. The antenna concept is to deposit antennas and leads on a polyimide film, such as Kapton, and to unroll the film on the lunar surface. The deployment technique utilized is to launch an anchor which pulls a double line from a reel at the spacecraft. Subsequently, the anchor is set by catching on the surface or collecting sufficient regolith. A motor then pulls in one end of the line, pulling the film off of its roller onto the lunar surface. Detection of a low frequency cutoff of the galactic radio background or of solar radio bursts by such a system would determine the maximum lunar ionospheric density at the time of measurement. The current design and testing, including videos of the deployment, will be presented. These activities are funded in part by the NASA Lunar Science Institute as an activity of the Lunar University Network for Astrophysical Research (LUNAR) consortium. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

MacDowall, Robert J.; Minetto, F. A.; Lazio, T. W.; Jones, D. L.; Kasper, J. C.; Burns, J. O.; Stewart, K. P.; Weiler, K. W.

2012-05-01

243

Mars Pathfinder mission operations: faster, better, cheaper on Mars.  

NASA Astrophysics Data System (ADS)

On July 4, 1997, the Mars Pathfinder spacecraft landed successfully in Ares Vallis, Mars. The following days and weeks were a whirlwind of scientific and technological achievement, as the lander and rover met and exceeded all of the mission objectives. This accomplishment is clear evidence that the faster, better, cheaper implementation approach can result in highly successful and low cost missions. A number of innovative design, fabrication,and management techniques were used to build and launch the spacecraft within the cost cap. The same faster, better, cheaper spirit was also applied to develop the mission operations system and conduct operations through cruise and surface operations. The highly operable designs of the Flight System and Ground Data System enabled an operations architecture in which most activities were performed by a core group of functional generalists. This group consisted of experienced development and test personnel whose skills were augmented with cross-training and contingency testing. The small size of this team combined with a flat management structure permitted highly streamlined and efficient operational processes. This efficiency was critical during the surface mission when daily updates to the operations plan were performed.

Cook, R.

244

Dock and Pak regulate olfactory axon pathfinding in Drosophila.  

PubMed

The convergence of olfactory axons expressing particular odorant receptor (Or) genes on spatially invariant glomeruli in the brain is one of the most dramatic examples of precise axon targeting in developmental neurobiology. The cellular and molecular mechanisms by which olfactory axons pathfind to their targets are poorly understood. We report here that the SH2/SH3 adapter Dock and the serine/threonine kinase Pak are necessary for the precise guidance of olfactory axons. Using antibody localization, mosaic analyses and cell-type specific rescue, we observed that Dock and Pak are expressed in olfactory axons and function autonomously in olfactory neurons to regulate the precise wiring of the olfactory map. Detailed analyses of the mutant phenotypes in whole mutants and in small multicellular clones indicate that Dock and Pak do not control olfactory neuron (ON) differentiation, but specifically regulate multiple aspects of axon trajectories to guide them to their cognate glomeruli. Structure/function studies show that Dock and Pak form a signaling pathway that mediates the response of olfactory axons to guidance cues in the developing antennal lobe (AL). Our findings therefore identify a central signaling module that is used by ONs to project to their cognate glomeruli. PMID:12588847

Ang, Lay-Hong; Kim, Jenny; Stepensky, Vitaly; Hing, Huey

2003-04-01

245

Soil-like deposits observed by Sojourner, the Pathfinder rover  

USGS Publications Warehouse

Most of the soil-like materials at the Pathfinder landing site behave like moderately dense soils on Earth with friction angles near 34??-39?? and are called cloddy deposits. Cloddy deposits appear to be poorly sorted with dust-sized to granule-sized mineral or rock grains; they may contain pebbles, small rock fragments, and clods. Thin deposits of porous, compressible drifts with friction angles near 26??-28?? are also present. Drifts are fine grained. Cohesions of both types of deposits are small. There may be indurated soil-like deposits and/or coated or crusted rocks. Cloddy deposits may be fluvial sediments of the Ares-Tiu floods, but other origins, such as ejecta from nearby impact craters, should be considered. Drifts are probably dusts that settled from the Martian atmosphere. Remote-sensing signatures of the deposits inferred from rover observations are consistent with those observed from orbit and Earth. Copyright 1999 by the American Geophysical Union.

Moore, H. J.; Bickler, D. B.; Crisp, J. A.; Eisen, H. J.; Gensler, J. A.; Haldemann, A. F. C.; Matijevic, J. R.; Reid, L. K.; Pavlics, F.

1999-01-01

246

Miocene reefs of Dominican Republic  

SciTech Connect

The reefs are overlain by conglomeratic strata. The stratigraphic setting of these reefs suggests that they have developed along the stalled portions of rapidly prograding fan deltas. Thickets and layers of coral debris are found seaward and stratigraphically above the well-developed reef. The matrix sediments are exclusively fine-grained sand to mud, and the fauna are suggestive of more open shelf conditions. In thickets, branched (porites spp., Pocillopora spp.), small massive (Montastrea spp., Siderastrea spp.), and foliose or plate like (Agaricia spp.) corals are found upright in the muddy sediment. Similarities in coral species and areal proximity suggest that thickets are the source of most layers of coralline debris. The association of coral debris with graded bedding and cross-bedding suggests that coral debris has been reworked by storms. The growth of corals and development of coral reefs in the Miocene-Pliocene Yaque Group is limited only by opportunities created by the slowing of siliciclastic sedimentation. Soft, muddy, terrigenous substrates and a continuing supply of terrigenous mud exert only a limited, indirect effect on reef growth.

Evans, C.C.

1988-01-01

247

“Faster, better, cheaper” technologies used in the attitude and information management subsystem for the Mars Pathfinder mission  

Microsoft Academic Search

The “Faster, Better, Cheaper” thrust at NASA\\/JPL has pushed new technologies into spacecraft designed for interplanetary missions. This is especially true for “Discovery” class missions such as Mars Pathfinder. This mission is set to send a lander and enclosed microrover to the surface of Mars for a “low cost”. The Pathfinder flight system must be built for $150M (FY92 dollars)

D. F. Woerner; David H. Lehman

1995-01-01

248

Digital photogrammetric analysis of the IMP camera images: Mapping the Mars Pathfinder landing site in three dimensions  

Microsoft Academic Search

This paper describes our photogrammetric analysis of the Imager for Mars Pathfinder data, part of a broader program of mapping the Mars Pathfinder landing site in support of geoscience investigations. This analysis, carried out primarily with a commercial digital photogrammetric system, supported by our in-house Integrated Software for Imagers and Spectrometers (ISIS), consists of three steps: (1) geometric control: simultaneous

R. L. Kirk; E. Howington-Kraus; T. Hare; E. Dorrer; D. Cook; K. Becker; K. Thompson; B. Redding; J. Blue; D. Galuszka; E. M. Lee; L. R. Gaddis; J. R. Johnson; L. A. Soderblom; A. W. Ward; P. H. Smith; D. T. Britt

1999-01-01

249

Mars Pathfinder Microrover Flight Experiment - a paradigm for very low-cost spacecraft.  

NASA Astrophysics Data System (ADS)

The Mars Pathfinder Microrover Flight Experiment (MFEX) will be carried by the Mars Pathfinder mission to the surface of Mars, where it will perform technology, science and Mars mission engineering experiments in July 1997. The Mars Pathfinder microrover is self-contained; it takes pictures; carries and supports a science instrument (an Alpha-Proton-X-Ray spectrometer); performs technology experiments (e.g. for soil mechanics and small vehicle mobility in an unknown terrain); is commanded; collects, stores, packetizes and downlinks data; monitors and controls its attitude and autonomously navigates; actively manages its power and its thermal control; and telecommunicates. In addition it functions on the Martian surface. On top of that, the microrover must interact with and respond to its environment in an "intelligent" fashion to carry out its mission and avoid hazards in an uncertain terrain. The factors which allow this are discussed.

Shirley, D. L.

250

The Lisa Technology Package (LTP) Diagnostics In Lisa Pathfinder  

NASA Astrophysics Data System (ADS)

LISA PathFinder (LPF) will be flown with the objective to test in space key technologies

Sanjuan, Josep; Lobo, A.; Cañizares, P.; Conchillo, A.; Conchillo, A.; Gesa, L.; Grimani, C.; Lloro, I.; Mateos, I.; Nofrarias, M.; Ramos-Castro, J.; Sopuerta, C.

2010-01-01

251

CMPF: Class-switching minimized pathfinding in metabolic networks  

PubMed Central

Background The metabolic network is an aggregation of enzyme catalyzed reactions that converts one compound to another. Paths in a metabolic network are a sequence of enzymes that describe how a chemical compound of interest can be produced in a biological system. As the number of such paths is quite large, many methods have been developed to score paths so that the k-shortest paths represent the set of paths that are biologically meaningful or efficient. However, these approaches do not consider whether the sequence of enzymes can be manufactured in the same pathway/species/localization. As a result, a predicted sequence might consist of groups of enzymes that operate in distinct pathway/species/localization and may not truly reflect the events occurring within cell. Results We propose a path weighting method CMPF (Class-switching Minimized Pathfinder) to search for routes in a metabolic network which minimizes pathway switching. In biological terms, a pathway is a series of chemical reactions which define a specific function (e.g. glycolysis). We conjecture that routes that cross many pathways are inefficient since different pathways define different metabolic functions. In addition, native routes are also well characterized within pathways, suggesting that reasonable paths should not involve too many pathway switches. Our method can be generalized when reactions participate in a class set (e.g., pathways, species or cellular localization) so that the paths predicted have minimal class crossings. Conclusions We show that our method generates k-paths that involve the least number of class switching. In addition, we also show that native paths are recoverable and alternative paths deviates less from native paths compared to other methods. This suggests that paths ranked by our method could be a way to predict paths that are likely to occur in biological systems.

2012-01-01

252

Heparan Sulfate Regulates Intraretinal Axon Pathfinding by Retinal Ganglion Cells  

PubMed Central

Purpose. Heparan sulfate (HS) is abundantly expressed in the developing neural retina; however, its role in the intraretinal axon guidance of retinal ganglion cells (RGCs) remains unclear. In this study, the authors examined whether HS was essential for the axon guidance of RGCs toward the optic nerve head. Methods. The authors conditionally ablated the gene encoding the exostosin-1 (Ext1) enzyme, using the dickkopf homolog 3 (Dkk3)-Cre transgene, which disrupted HS expression in the mouse retina during directed pathfinding by RGC axons toward the optic nerve head. In situ hybridization, immunohistochemistry, DiI tracing, binding assay, and retinal explant assays were performed to evaluate the phenotypes of the mutants and the roles of HS in intraretinal axon guidance. Results. Despite no gross abnormality in RGC distribution, the mutant RGC axons exhibited severe intraretinal guidance errors, including optic nerve hypoplasia, ectopic axon penetration through the full thickness of the neural retina and into the subretinal space, and disturbance of the centrifugal projection of RGC axons toward the optic nerve head. These abnormal phenotypes shared similarities with the RGC axon misguidance caused by mutations of genes encoding Netrin-1 and Slit-1/2. Explant assays revealed that the mutant RGCs exhibited disturbed Netrin-1–dependent axon outgrowth and Slit-2–dependent repulsion. Conclusions. The present study demonstrated that RGC axon projection toward the optic nerve head requires the expression of HS in the neural retina, suggesting that HS in the retina functions as an essential modulator of Netrin-1 and Slit-mediated intraretinal RGC axon guidance.

Ogata-Iwao, Minako; Iwao, Keiichiro; Takihara, Yuji; Nakaishi-Fukuchi, Yuko; Irie, Fumitoshi; Sato, Shigeru; Furukawa, Takahisa; Yamaguchi, Yu; Tanihara, Hidenobu

2011-01-01

253

Uranus Pathfinder: Exploring the Origins and Evolution of Ice Giants  

NASA Astrophysics Data System (ADS)

The "Ice Giants" Uranus and Neptune are a different class of planet compared to Jupiter and Saturn. Studying these objects is important for furthering our understanding of the formation and evolution of the planets, and unravelling the fundamental physical and chemical processes in the Solar System. The importance of filling these gaps in our knowledge of the Solar System is particularly acute when trying to apply our understanding to the numerous planetary systems that have been discovered around other stars. The Uranus Pathfinder (UP) mission [1] thus represents the quintessential aspects of the objectives of the European planetary community as expressed in ESA's Cosmic Vision 2015-2025. UP was proposed to the European Space Agency's M3 call for medium-class missions in 2010 and proposed to be the first orbiter of an Ice Giant planet. As the most accessible Ice Giant within the M-class mission envelope Uranus was identified as the mission target. Although not selected for this call the UP mission concept provides a baseline framework for the exploration of Uranus with existing low-cost platforms and underlines the need to develop power sources suitable for the outer Solar System. The UP science case is based around exploring the origins, evolution, and processes at work in Ice Giant planetary systems. Three broad themes were identified: (1) Uranus as an Ice Giant, (2) An Ice Giant planetary system, and (3) An asymmetrical magnetosphere. Due to the long interplanetary transfer from Earth to Uranus a significant cruisephase science theme was also developed. The science payload has a strong heritage in Europe and beyond and requires no significant technology developments. In this paper we discuss this European effort to explore Uranus and outline ongoing developments of the mission concept.

Arridge, C. S.

2012-09-01

254

NOAA Coral Reef Watch: Remote Sensing and Coral Reefs  

NSDL National Science Digital Library

Developed by a fifth grade teacher, the Remote Sensing and Coral Reefs curriculum includes lesson plans, which feature links to additional information, and PowerPoint presentations. Topics discussed include altimetry, phytoplankton and ocean color, symbiosis and coral anatomy, sea surface temperature and coral bleaching, and conservation. The lesson plans can be used in sequence or by themselves.

255

Spinocerebellar ataxia type 13 mutation that is associated with disease onset in infancy disrupts axonal pathfinding during neuronal development.  

PubMed

Spinocerebellar ataxia type 13 (SCA13) is an autosomal dominant disease caused by mutations in the Kv3.3 voltage-gated potassium (K(+)) channel. SCA13 exists in two forms: infant onset is characterized by severe cerebellar atrophy, persistent motor deficits and intellectual disability, whereas adult onset is characterized by progressive ataxia and progressive cerebellar degeneration. To test the hypothesis that infant- and adult-onset mutations have differential effects on neuronal development that contribute to the age at which SCA13 emerges, we expressed wild-type Kv3.3 or infant- or adult-onset mutant proteins in motor neurons in the zebrafish spinal cord. We characterized the development of CaP (caudal primary) motor neurons at ?36 and ?48 hours post-fertilization using confocal microscopy and 3D digital reconstruction. Exogenous expression of wild-type Kv3.3 had no significant effect on CaP development. In contrast, CaP neurons expressing the infant-onset mutation made frequent pathfinding errors, sending long, abnormal axon collaterals into muscle territories that are normally innervated exclusively by RoP (rostral primary) or MiP (middle primary) motor neurons. This phenotype might be directly relevant to infant-onset SCA13 because interaction with inappropriate synaptic partners might trigger cell death during brain development. Importantly, pathfinding errors were not detected in CaP neurons expressing the adult-onset mutation. However, the adult-onset mutation tended to increase the complexity of the distal axonal arbor. From these results, we speculate that infant-onset SCA13 is associated with marked changes in the development of Kv3.3-expressing cerebellar neurons, reducing their health and viability early in life and resulting in the withered cerebellum seen in affected children. PMID:22736459

Issa, Fadi A; Mock, Allan F; Sagasti, Alvaro; Papazian, Diane M

2012-06-26

256

Coral skeletons provide historical evidence of phosphorus runoff on the great barrier reef.  

PubMed

Recently, the inshore reefs of the Great Barrier Reef have declined rapidly because of deteriorating water quality. Increased catchment runoff is one potential culprit. The impacts of land-use on coral growth and reef health however are largely circumstantial due to limited long-term data on water quality and reef health. Here we use a 60 year coral core record to show that phosphorus contained in the skeletons (P/Ca) of long-lived, near-shore Porites corals on the Great Barrier Reef correlates with annual records of fertiliser application and particulate phosphorus loads in the adjacent catchment. Skeletal P/Ca also correlates with Ba/Ca, a proxy for fluvial sediment loading, again linking near-shore phosphorus records with river runoff. Coral core records suggest that phosphorus levels increased 8 fold between 1949 and 2008 with the greatest levels coinciding with periods of high fertiliser-phosphorus use. Periods of high P/Ca correspond with intense agricultural activity and increased fertiliser application in the river catchment following agricultural expansion and replanting after cyclone damage. Our results demonstrate how coral P/Ca records can be used to assess terrestrial nutrient loading of vulnerable near-shore reefs. PMID:24086606

Mallela, Jennie; Lewis, Stephen E; Croke, Barry

2013-09-27

257

Coral Skeletons Provide Historical Evidence of Phosphorus Runoff on the Great Barrier Reef  

PubMed Central

Recently, the inshore reefs of the Great Barrier Reef have declined rapidly because of deteriorating water quality. Increased catchment runoff is one potential culprit. The impacts of land-use on coral growth and reef health however are largely circumstantial due to limited long-term data on water quality and reef health. Here we use a 60 year coral core record to show that phosphorus contained in the skeletons (P/Ca) of long-lived, near-shore Porites corals on the Great Barrier Reef correlates with annual records of fertiliser application and particulate phosphorus loads in the adjacent catchment. Skeletal P/Ca also correlates with Ba/Ca, a proxy for fluvial sediment loading, again linking near-shore phosphorus records with river runoff. Coral core records suggest that phosphorus levels increased 8 fold between 1949 and 2008 with the greatest levels coinciding with periods of high fertiliser-phosphorus use. Periods of high P/Ca correspond with intense agricultural activity and increased fertiliser application in the river catchment following agricultural expansion and replanting after cyclone damage. Our results demonstrate how coral P/Ca records can be used to assess terrestrial nutrient loading of vulnerable near-shore reefs.

Mallela, Jennie; Lewis, Stephen E.; Croke, Barry

2013-01-01

258

High Latitude Reefs: A Potential Refuge for Reef Builders  

NASA Astrophysics Data System (ADS)

Coral reefs globally show variable signs of deterioration or community structure changes due to a host of anthropogenic and natural factors. In these global scenarios, rates of calcification by reef builders such as Scleractinian corals are predicted to significantly decline in the future due to the increase in atmospheric CO_2. When considering the response of reefs to the present climate change, temperature effects should also be taken into account. Here, we investigate the simultaneous impact of temperature and CO_2 on the high-latitude Bermuda coral reef system (32^oN, 64^oE)through a series of in vitro experiments at different CO_2 levels and seasonally different summer (27^oC) and winter (20^oC) temperature conditions. Four species of Scleractinian corals (Porites astreoides, Diploria labyrinthiformis, Madracis mirabilis and decactis) were acclimated for three months at: 20^oC and 27^oC (both with CO_2 levels at 400 ppm (control) and 700 ppm). Growth was assessed by buoyant weight techniques during the acclimation period. Photosynthesis, respiration and calcification were measured at the end of this period using respirometric chambers. A reproduction experiment was also undertaken under 27^oC. Photosynthesis mainly remains constant or increases under high CO_2 conditions. The results of the integrated calcification measurements confirm the hypothesis that an increase in CO_2 induces a decrease in calcification. However an increase in photosynthesis can be observed when CO_2 is unfavorable for calcification suggesting that a biological control of calcification through photosynthesis could prevent a drop in the calcification potential. Buoyant weight results indicate that the CO_2 impact could be less detrimental under lower temperature. This result will be compared with the instantaneous calcification measurements in the chambers and some in situ coral growth assessments in winter and summer conditions. The consequences for the response of marginal reefs undergoing high seasonal temperature variations will finally be discussed.

Amat, A.; Bates, N.

2003-04-01

259

Contradictions to Darwin's Evolution of Reef Types in Barrier Reef Relationships  

NASA Astrophysics Data System (ADS)

The Darwinian progressive subsidence model for the evolution of fringing reefs, barrier reefs and atolls has been generally accepted following the indisputable proof of subsidence provided by drilling results in the Pacific. Nonetheless, there are data that do not fit the expectations of the model, such as the similar lagoon depths of barrier reefs and atolls as opposed to the subsidence theory's implicit prediction that atolls should have significantly greater depths. In contrast, much evidence supports the influence of meteoric-water solution on barrier reef morphology. For example, the maximum lagoon depth of the 56 modern barrier reefs is statistically correlated with the lagoon catchment area for modern annual rainfall. These modern rainfall patterns are a reasonable proxy for relative geographic differences in glacial lowstand rainfall, even though the absolute amounts of such rainfall are unknown. The correlation therefore stongly suggests the importance of Pleistocene subaerial solution in contributing to barrier reef morphology. Further support for antecedent influence occurs in the form of barrier reef passes in which the depth of the reef pass is correlated with onshore drainage volumes. On a larger scale, the Cook Island of Mangaia provides evidence that solution can produce barrier reef morphology independent of reef development. In contrast, there are no examples of the Darwinian subsidence-predicted lagoon transition of fringing reefs to barrier reefs to atolls. Moreover, the common occurrence of fringing reefs within barrier reefs negates subsidence as a causal factor in their presumed progressive evolutionary development. Consequently, the evidence points to a solution morphology template which has been accentuated by reef construction to produce the diagnostic barrier reef morphology we see today. Rapid subsidence of seamounts by flexural loading during their early history, combined with Pleistocene sealevel fluctuations results in permanent drowning of older barrier reef. The importance of slower, thermal subsidence is in accounting for the overall thickness of the resulting carbonate caps.

Purdy, E.; Winterer, E. L.

2004-05-01

260

New evidence for the barrier reef model, Permian Capitan Reef complex, New Mexico  

SciTech Connect

Recent paleontologic and petrologic observations suggest that the Capitan Formation was deposited as an organic or ecologic reef that acted as an emergent barrier to incoming wave energy. In outcrops in the Guadalupe Mountains and within Carlsbad Caverns, massive reef boundstone contains a highly diverse assemblage of frame-building and binding organisms. In modern reefs, diversity among frame builders decreases dramatically with depth. Marine cement is abundant in reef boundstone, but limited in back-reef grainstone and packstone. This cementation pattern is similar to that observed in modern emergent barrier reef systems. Based on comparison with modern analogs, these dasycladrominated back-reef sediments and their associated biota are indicative of shallow, hypersaline conditions. Few of these dasyclads exhibit broken or abraded segments and some thallus sections are still articulated suggesting that low-energy, hypersaline conditions occurred immediately shelfward of the reef. In addition, large-scale topographic features, such as possible spur and groove structures between Walnut Canyon and Rattlesnake Canyon, and facies geometries, such as the reef to shelf transition, resemble those found in modern shallow-water reefs. The organisms that formed the Capitan Reef appear to have lived in, and responded to, physical and chemical conditions similar to those that control the geometry of modern shallow-water reefs. Like their modern counterparts, they seem to have strongly influenced adjacent environments. In light of this evidence, consideration should be given to either modifying or abandoning the marginal mound model in favor of the originally proposed barrier reef model.

Kirkland, B.L.; Moore, C.H. Jr. (Louisiana State Univ., Baton Rouge (USA))

1990-05-01

261

Biological destruction of coral reefs  

Microsoft Academic Search

The major agents of biological destruction of coral reefs can be divided into grazers, etchers and borers. Each of these groups is reviewed on a world wide basis, together with the mechanisms by which they destroy the coral substrate. Rates of bioerosion attributed to major agents of grazers, etchers and borers are given, together with limitations of some of the

P. A. Hutchings

1986-01-01

262

The future of coral reefs  

NASA Astrophysics Data System (ADS)

Coral reefs, with their millions of species, have changed profoundly because of the effects of people, and will continue to do so for the foreseeable future. Reefs are subject to many of the same processes that affect other human-dominated ecosystems, but some special features merit emphasis: (i) Many dominant reef builders spawn eggs and sperm into the water column, where fertilization occurs. They are thus particularly vulnerable to Allee effects, including potential extinction associated with chronic reproductive failure. (ii) The corals likely to be most resistant to the effects of habitat degradation are small, short-lived "weedy" corals that have limited dispersal capabilities at the larval stage. Habitat degradation, together with habitat fragmentation, will therefore lead to the establishment of genetically isolated clusters of inbreeding corals. (iii) Increases in average sea temperatures by as little as 1°C, a likely result of global climate change, can cause coral "bleaching" (the breakdown of coral-algal symbiosis), changes in symbiont communities, and coral death. (iv) The activities of people near reefs increase both fishing pressure and nutrient inputs. In general, these processes favor more rapidly growing competitors, often fleshy seaweeds, and may also result in explosions of predator populations. (v) Combinations of stress appear to be associated with threshold responses and ecological surprises, including devastating pathogen outbreaks. (vi) The fossil record suggests that corals as a group are more likely to suffer extinctions than some of the groups that associate with them, whose habitat requirements may be less stringent.

Knowlton, Nancy

2001-05-01

263

The Formation of Coral Reefs  

Microsoft Academic Search

IN NATURE for February 18 there is a paper by Mr. J. S. Gardiner giving a concise account of his theory of coral reefs. A more extended paper by him on the same subject appeared in the Geographical Journal for 1902, and was followed last year by one by Mr. Günther on erosion on the west coast of Italy; the

Ernest H. L. Schwarz

1904-01-01

264

Biological models for Mesozoic reef evolution  

SciTech Connect

Throughout the Mesozoic, shallow-water carbonate ramps and platforms of the circumequatorial Tethyan Ocean were characterized by extensive development of reef ecosystems, especially during times of eustatic highstand, expansion of the Tropics, and warm equable global climates. The greatest reef development was north of the paleoequator in the Caribbean and Indo-Mediterranean provinces. These reefs and associated debris facies comprise major petroleum reservoirs, in some cases with remarkable porosity and permeability normally attributed to a combination of sedimentologic, tectonic, and diagenetic factors. The biological evolution of Mesozoic reefs also has had an important, and in some cases dominant, role in determining reservoir quality. Three major biological factors are critical to mesozoic reef-associated reservoir development: (1) the replacement/competitive displacement of coral-algal dominated, highly integrated reef ecosystems by loosely packed rudistid bivalve-dominated reef ecosystems in the Barremian-Albian; (2) the evolution of dominantly aragonitic, highly porous shells among framework-building rudistids in the middle and Late Cretaceous; and (3) competitive strategies among rudistids that effectively prevented widespread biological binding of Cretaceous reefs, leading to the production of large marginal fans that comprise major carbonate reservoirs. Detailed studies of these evolutionary trends in reef/framework development and of the distribution of different groups of bioconstructors on reefs lead to predictive modeling for primary and secondary porosity development in mesozoic carbonate reservoirs. The competitive displacement of coral-algal communities by rudistids on Cretaceous reefs was so effective that, even after Maastrichtian mass extinction of rudistids and other important groups comprising Mesozoic reef/carbonate platform ecosystems, coral-algal reef-building communities did not evolve again until the late Eocene.

Kauffman, E.G. (Univ. of Colorado, Boulder (USA))

1990-11-01

265

Battelle developing reefs to ease habitat losses  

SciTech Connect

Artificial reefs may be the answer to solving a worldwide problem of declining fish habitats, or they may only be good for creating fishing spots. Researchers at Battelle's Ocean Sciences Laboratory in Duxbury, Massachusetts, are studying artificial reefs in the Delaware River to determine if they are a solution to habitat losses in estuaries and coastal regions. [open quotes]Right now, we don't know if the fish are using the reefs simply as a grazing land, and then moving on, or if they're using the areas to colonize,[close quotes] said researcher Karen Foster. [open quotes]Ultimately, we hope to find they are colonizing.[close quotes] In 1989, Battelle researchers placed 16 prefabricated concrete reefs 45 feet deep in Delaware Bay. The reefs were placed in clusters of four, and monitoring began the following year. The federal government ordered the reefs placed in the bay as a mitigation technique for fish habitat that was lost when the river was dredged for navigational purposes. Researchers examined the reefs twice last summer. It will take five years, Foster said, before researchers can determine if the reefs are increasing the fish population. Early tests show, however, the populations of mussels, sponges, corals, and anemones increased by up to 150 percent over an area of bay bottom where the reefs were placed. Divers take crustacean samples from the reefs, and fish are caught near the reefs for examination. Researchers dissect the fish stomachs and analyze the contents to determine if they have been feeding at the reefs. [open quotes]If we find blue mussels in the stomach of the fish, that's great because we know that blue mussels are growing on the reef,[close quotes] Foster said.

Not Available

1993-04-01

266

Sedimentation on three caribbean atolls: Glovers reef, lighthouse reef and turneffe Islands, belize  

Microsoft Academic Search

Summary  The chief mode of carbonate sedimentation on the Belizean atolls Glovers Reef, Lighthouse Reef and Turneffe Islands is the\\u000a accumulation of organically-derived particles. Variations in the distribution of the composition and grain-sizes of surface\\u000a sediments, collected along transects across the atolls, are environmentally controlled. Two major sediment types may be distinguished.\\u000a (1) Reef and fore reef sediments are dominated by

Eberhard Gischler

1994-01-01

267

Trade off analysis for participatory coral reef management: lessons learned from Buccoo Reef Marine Park, Tobago  

Microsoft Academic Search

Coral reefs provide a range of important functions and services, yet often conflicts exist over coral reef use among multiple users. This paper outlines the trade-off analysis approach to coral reef management where multiple and conflicting objectives for coral reef resources can be identified, assessed and reconciled within a decision-support framework. The paper applies trade-off analysis to the case of

E. Tompkins; K. Brown; W. N. Adger; P. Bacon; K. Young; D. Shim

268

Episodes of reef growth at Lord Howe Island, the southernmost reef in the southwest Pacific  

NASA Astrophysics Data System (ADS)

Lord Howe Island lies at the present latitudinal limit to reef growth in the Pacific and preserves evidence of episodes of reef development over the Late Quaternary. A modern fringing reef flanks the western shore of Lord Howe Island, enclosing a Holocene lagoon, and Late Quaternary eolianites veneer the island. Coral-bearing beach and shallow-water calcarenites record a sea level around 2 3 m above present during the Last Interglacial. No reefs or subaerial carbonate deposits occur on, or around, Balls Pyramid, 25 km to the south. The results of chronostratigraphic studies of the modern Lord Howe Island reef and lagoon indicate prolific coral production during the mid-Holocene, but less extensive coral cover during the late Holocene. Whereas the prolific mid-Holocene reefs might appear to reflect warmer sea-surface temperatures, the pattern of dates and reef growth history are similar to those throughout the Great Barrier Reef and across much of the Indo-Pacific and are more likely correlated with availability of suitable substrate. Little direct evidence of a Last Interglacial reef is now preserved, and the only evidence for older periods of reef establishment comes from clasts of coral in a well-cemented limestone unit below a coral that has been dated to the Last Interglacial age in a core at the jetty. However, a massive reef structure occurs near the centre of the wide shelf around Lord Howe Island, veneered with Holocene coralline algae. Its base is 40 50 m deep and it rises to water depths of less than 30 m. This fossil reef is several times more extensive than either Holocene or Last Interglacial reefs appear to have been. Holocene give-up reef growth is inferred during the postglacial transgression, but an alternative interpretation is that this is a much older landform, indicating reefs that were much more extensive than modern reefs at this marginal site.

Woodroffe, C. D.; Dickson, M. E.; Brooke, B. P.; Kennedy, D. M.

2005-12-01

269

ReefLink Database: A decision support tool for Linking Coral Reefs and Society Through Systems Thinking  

EPA Science Inventory

Coral reefs provide the ecological foundation for productive and diverse fish and invertebrate communities that support multibillion dollar reef fishing and tourism industries. Yet reefs are threatened by growing coastal development, climate change, and over-exploitation. A key i...

270

Dynamic fragility of oceanic coral reef ecosystems  

PubMed Central

As one of the most diverse and productive ecosystems known, and one of the first ecosystems to exhibit major climate-warming impacts (coral bleaching), coral reefs have drawn much scientific attention to what may prove to be their Achilles heel, the thermal sensitivity of reef-building corals. Here we show that climate change-driven loss of live coral, and ultimately structural complexity, in the Seychelles results in local extinctions, substantial reductions in species richness, reduced taxonomic distinctness, and a loss of species within key functional groups of reef fish. The importance of deteriorating physical structure to these patterns demonstrates the longer-term impacts of bleaching on reefs and raises questions over the potential for recovery. We suggest that isolated reef systems may be more susceptible to climate change, despite escaping many of the stressors impacting continental reefs.

Graham, Nicholas A. J.; Wilson, Shaun K.; Jennings, Simon; Polunin, Nicholas V. C.; Bijoux, Jude P.; Robinson, Jan

2006-01-01

271

Philippine Coral Reefs Under Threat: Lessons Learned After 25 Years of Community-Based Reef Conservation  

Microsoft Academic Search

The Philippine archipelago consists of more than 7000 islands. Most of these islands have extensive coral reefs or coral communities. For centuries, reefs and their associated resources have provided the livelihood for a large portion of the coastal population. However, reefs as sources of income are threatened by over-exploitation and by the use of destructive fishing methods. The scientific community,

Alan T White; Helge P Vogt

2000-01-01

272

Larval reef fish could use odour for detection, retention and orientation to reefs  

Microsoft Academic Search

While evidence is mounting that larval reef fish are active participants in the process of dispersal and settlement, the sensory and behavioural mechanisms by which these fishes disperse and return from their oceanic phase to the reefs remain unknown. On One Tree Island (Great Barrier Reef, Australia), we tested freshly collected animals in a large choice-flume on the shore. Here,

Jelle Atema; Michael J. Kingsford; Gabriele Gerlach

2002-01-01

273

New evidence for the barrier reef model, Permian Capitan Reef complex, New Mexico  

Microsoft Academic Search

Recent paleontologic and petrologic observations suggest that the Capitan Formation was deposited as an organic or ecologic reef that acted as an emergent barrier to incoming wave energy. In outcrops in the Guadalupe Mountains and within Carlsbad Caverns, massive reef boundstone contains a highly diverse assemblage of frame-building and binding organisms. In modern reefs, diversity among frame builders decreases dramatically

B. L. Kirkland; C. H. Jr. Moore

1990-01-01

274

Live coral cover in the fossil record: an example from Holocene reefs of the Dominican Republic  

NASA Astrophysics Data System (ADS)

Fossil reefs hold important ecological information that can provide a prehuman baseline for understanding recent anthropogenic changes in reefs systems. The most widely used proxy for reef "health," however, is live coral cover, and this has not been quantified in the fossil record because it is difficult to establish that even adjacent corals were alive at the same time. This study uses microboring and taphonomic proxies to differentiate between live and dead corals along well-defined time surfaces in Holocene reefs of the Enriquillo Valley, Dominican Republic. At Cañada Honda, live coral cover ranged from 59 to 80% along a contemporaneous surface buried by a storm layer, and the reef, as a whole had 33-80% live cover within the branching, mixed, massive and platy zones. These values equal or exceed those in the Dominican Republic and Caribbean today or reported decades ago. The values from the western Dominican Republic provide a geologic baseline against which modern anthropogenic changes in Caribbean reefs can be considered.

Lescinsky, H.; Titus, B.; Hubbard, D.

2012-06-01

275

Characterization of the Martian surface deposits by the Mars Pathfinder rover, Sojourner  

Microsoft Academic Search

The Mars Pathfinder rover discovered pebbles on the surface and in rocks that may be sedimentary - not volcanic - in origin. Surface pebbles may have been rounded by Ares flood waters or liberated by weathering of sedimentary rocks called conglomerates. Conglomerates imply that water existed elsewhere and earlier than the Ares flood. Most soil-like deposits are similar to moderately

J. R. Matijevic; J. Crisp; D. B. Bickler; R. S. Banes; B. K. Cooper; H. J. Eisen; J. Gensler; A. Haldemann; F. Hartman; K. A. Jewett; L. H. Matthies; S. L. Laubach; A. H. Mishkin; J. C. Morrison; T. T. Nguyen; A. R. Sirota; H. W. Stone; S. Stride; L. F. Sword; J. A. Tarsala; A. D. Thompson; M. T. Wallace; R. Welch; E. Wellman; B. H. Wilcox; D. Ferguson; P. Jenkins; J. Kolecki; G. A. Landis; D. Wilt

1997-01-01

276

Global Climate Change Pathfinder: A Guide to Information Resources. Second Edition.  

ERIC Educational Resources Information Center

|This pathfinder is a guide to scientific and technical aspects of global climate change including meteorological and climatological aspects; biological, agricultural, and public policy implications; and the chemical processes involved. Sources are arranged by type of publication and include: (1) 10 reference sources; (2) 12 bibliographies; (3) 44…

Pintozzi, Chestalene; Jones, Douglas E.

277

Rock coatings and aeolian abrasion on Mars: Application to the Pathfinder landing site  

Microsoft Academic Search

Rock coatings can be used to constrain the rate of abrasion by wind on Mars. The susceptibility to abrasion for potential rock coatings on Mars (salt\\/salt-cemented coatings, rock varnish, and amorphous silica) were determined experimentally. Rock coatings generally abrade more easily than the host rock, although amorphous silica is an exception. If coatings exist on rocks at the Mars Pathfinder

Michael D. Kraft; Ronald Greeley

2000-01-01

278

Pathfinder Networks and Author Cocitation Analysis: A Remapping of Paradigmatic Information Scientists.  

ERIC Educational Resources Information Center

Discussion of author cocitation analysis focuses on Pathfinder Networks (PFNET) where nodes represent authors and links represent weighted paths between nodes, the weights being cocitation counts. Highlights include remapping information science; comparison with principal components analysis; a correlation-based PFNET; and AuthorLink, a Web-based…

White, Howard D.

2003-01-01

279

LINC-NIRVANA Pathfinder: testing the next generation of wave front sensors at LBT  

NASA Astrophysics Data System (ADS)

LINC-NIRVANA will employ four wave front sensors to realize multi-conjugate correction on both arms of a Fizeau interferometer for LBT. Of these, one of the two ground-layer wave front sensors, together with its infrared test camera, comprise a stand-alone test platform for LINC-NIRVANA. Pathfinder is a testbed for full LINC-NIRVANA intended to identify potential interface problems early in the game, thus reducing both technical, and schedule, risk. Pathfinder will combine light from multiple guide stars, with a pyramid sensor dedicated to each star, to achieve ground-layer AO correction via an adaptive secondary: the 672-actuator thin shell at the LBT. The ability to achieve sky coverage by optically coadding light from multiple stars has been previously demonstrated; and the ability to achieve correction with an adaptive secondary has also been previously demonstrated. Pathfinder will be the first system at LBT to combine both of these capabilities. Since reporting our progress at A04ELT2, we have advanced the project in three key areas: definition of specific goals for Pathfinder tests at LBT, more detail in the software design and planning, and calibration. We report on our progress and future plans in these three areas, and on the project overall.

Conrad, Albert R.; Arcidiacono, Carmelo; Baumeister, Harald; Bergomi, Maria; Bertram, Thomas; Berwein, Juergen; Biddick, Chris; Bizenberger, Peter; Brangier, Matthieu; Briegel, Florian; Brunelli, Alessandro; Brynnel, Joar; Busoni, Lorenzo; Cushing, Norm; De Bonis, Fulvio; De La Pena, Michele; Esposito, Simone; Farinato, Jacopo; Fini, Luca; Green, Richard F.; Herbst, Tom; Hofferbert, Ralph; Kittmann, Frank; Kuerster, Martin; Laun, Werner; Meschke, Daniel; Mohr, Lars; Pavlov, Aleksei; Pott, Jorg-Uwe; Puglisi, Alfio; Ragazzoni, Roberto; Rakich, Andrew; Rohloff, Ralf-Rainer; Trowitzsch, Jan; Viotto, Valentina; Zhang, Xianyu

2012-07-01

280

Mars Pathfinder landing site: Evidence for a change in wind regime from lander and orbiter data  

Microsoft Academic Search

Surface features related to the wind are observed in the vicinity of the Mars Pathfinder (MPF) landing site data from the lander and in data from orbit by the Viking Orbiter and Mars Global Surveyor missions. Features seen from the surface include wind tails associated with small rocks, barchanoid duneforms, ripplelike patterns, and ventifact flutes cut into some rocks. Features

Ronald Greeley; Michael D. Kraft; Ruslan O. Kuzmin; Nathan T. Bridges

2000-01-01

281

The Advanced Very High Resolution Radiometer Pathfinder Atmosphere (PATMOS) Climate Dataset: A Resource for Climate Research  

Microsoft Academic Search

As part of the joint National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) Pathfinder program, the NOAA National Environmental Satellite, Data, and Information Service (NESDIS) has created a research-quality global atmospheric dataset through the reprocessing of Advanced Very High Resolution Radiometer (AVHRR) observations since 1981. The AVHRR is an imaging radiometer that flies on NOAA

Herbert Jacobowitz; Larry L. Stowe; George Ohring; Andrew Heidinger; Kenneth Knapp; Nicholas R. Nalli

2003-01-01

282

Calibration of the Mars Pathfinder alpha proton X-ray spectrometer  

NASA Astrophysics Data System (ADS)

The chemical compositions of Martian rocks and soils examined with the alpha proton X-ray spectrometer (APXS) during the Mars Pathfinder 1997 lander mission were not previously fully determined. Preliminary chemical results included major element abundances determined by the incomplete calibration of the X-ray mode. The data collected from the alpha and proton detectors were not previously analyzed due to significant atmospheric contributions to the spectra. The backup instrument of the Pathfinder alpha proton X-ray spectrometer flight instrument has been used to complete the instrument calibration under simulated Martian conditions at the University of Chicago. An APXS instrument has been used to create a Pathfinder calibration library to test the accuracy of all three instrument modes under simulated Martian conditions. This calibration library has been tested on a number of geologic standards. We have also corrected for instrument differences between the laboratory and flight units. Significant chemical results, somewhat different from those initially reported by Rieder et al. [1997a] and by Wänke et al. [2001], are reported by Foley et al. [2003] as a result of this reanalysis of the Pathfinder APXS data.

Foley, C. Nicole; Economou, Thanasis E.; Clayton, Robert N.; Dietrich, William

2003-11-01

283

North American Landscape Characterization (NALC). Pathfinder Project Research Plan. Global Change Research Program.  

National Technical Information Service (NTIS)

The project is a component of the National Aeronautics and Space Administration (NASA) Landsat Pathfinder program of experiments to study global change issues. The purpose of the project is to produce land cover and land cover change data products at sub-...

R. S. Lunetta J. G. Lyon J. A. Sturdevant J. L. Dwyer C. D. Elvidge L. K. Fenstermaker D. Yuan S. R. Hoffer R. Weerackoon

1993-01-01

284

Mineralogic and compositional properties of Martian soil and dust: Results from Mars Pathfinder  

Microsoft Academic Search

Mars Pathfinder obtained multispectral, elemental, magnetic, and physical measurements of soil and dust at the Sagan Memorial Station during the course of its 83 sol mission. We describe initial results from these measurements, concentrating on multispectral and elemental data, and use these data, along with previous Viking, SNC meteorite, and telescopic results, to help constrain the origin and evolution of

J. F. Bell; H. Y. McSween; J. A. Crisp; R. V. Morris; S. L. Murchie; N. T. Bridges; J. R. Johnson; D. T. Britt; M. P. Golombek; H. J. Moore; A. Ghosh; J. L. Bishop; R. C. Anderson; J. Brückner; T. Economou; J. P. Greenwood; H. P. Gunnlaugsson; R. M. Hargraves; S. Hviid; J. M. Knudsen; M. B. Madsen; R. Reid; R. Rieder; L. Soderblom

2000-01-01

285

Review of the trajectory and atmospheric structure reconstruction for Mars Pathfinder  

Microsoft Academic Search

Mars Pathfinder landed on Mars on July 4, 1997. It used a novel deceleration procedure, consisting of a hypersonic aeroshell, a transonic parachute, retro-rockets, and airbags, to reach the surface safely. Its aerodynamic properties passively maintained a near-zero angle of attack throughout its entry. There were no gyroscopes to monitor attitude. Several different trajectory reconstructions have been based on the

Paul Withers; Martin Towner; Brijen Hathi; John Zarnecki

2004-01-01

286

Using Virtual Reality For Science Mission Planning: A Mars Pathfinder Case  

Microsoft Academic Search

Mars Pathfinder Project requires a Ground Data System that supports both anengineering and a science payload with reduced mission operations and planningschedules. Also, successful surface operation of the lander camera requires efficient mission planningand accurate pointing of the camera,To meet these challenges, the GDS Team designed a new software strategy that integrates virtualreality technology with existing JPL Navigational Ancillary Information

Jacqueline H. Kim; Richard J. Weidner; Allan L. Sacks

1994-01-01

287

The atmosphere structure and meteorology instrument on the Mars Pathfinder lander  

Microsoft Academic Search

An instrument on the Pathfinder lander has been designed to measure the structure of Mars' atmosphere during spacecraft entry and descent from ~150km altitude to the surface, and to measure meteorological parameters after landing for the landed duration of the mission. This is specified to be nominally 30 Mars days but potentially up to 1 Earth year. Landed sensors will

Alvin Seiff; James E. Tillman; James R. Murphy; John T. Schofield; David Crisp; Jeffrey R. Barnes; Clayton LaBaw; Colin Mahoney; John D. Mihalov; Gregory R. Wilson; Robert Haberle

1997-01-01

288

The Rights of Muslim Women in the Middle East: A Pathfinder  

Microsoft Academic Search

This annotated pathfinder is designed to serve as a guide for those who wish to learn about the legal and social situation of Muslim women in the region of the Middle East, but who do not have a great amount of advanced knowledge concerning the topic. It is meant to serve as an organized starting point from which to begin

Lauren E. Schroeder

2009-01-01

289

Overview of the Mars Pathfinder Mission and Assessment of Landing Site Predictions  

Microsoft Academic Search

Chemical analyses returned by Mars Pathfinder indicate that some rocks may be high in silica, implying differentiated parent materials. Rounded pebbles and cobbles and a possible conglomerate suggest fluvial processes that imply liquid water in equilibrium with the atmosphere and thus a warmer and wetter past. The moment of inertia indicates a central metallic core of 1300 to 2000 kilometers

M. P. Golombek; R. A. Cook; T. Economou; W. M. Folkner; A. F. C. Haldemann; P. H. Kallemeyn; J. M. Knudsen; R. M. Manning; H. J. Moore; T. J. Parker; R. Rieder; J. T. Schofield; P. H. Smith; R. M. Vaughan

1997-01-01

290

Overview of the Mars Pathfinder Mission: Launch through landing, surface operations, data sets, and science results  

Microsoft Academic Search

Mars Pathfinder successfully landed at Ares Vallis on July 4, 1997, deployed and navigated a small rover about 100 m clockwise around the lander, and collected data from three science instruments and ten technology experiments. The mission operated for three months and returned 2.3 Gbits of data, including over 16,500 lander and 550 rover images, 16 chemical analyses of rocks

M. P. Golombek; N. T. Bridges; H. J. Moore; S. L. Murchie; J. R. Murphy; T. J. Parker; R. Rieder; T. P. Rivellini; J. T. Schofield; A. Seiff; R. B. Singer; P. H. Smith; L. A. Soderblom; D. A. Spencer; C. R. Stoker; R. Sullivan; N. Thomas; S. W. Thurman; M. G. Tomasko; R. M. Vaughan; H. Wänke; A. W. Ward; G. R. Wilson; R. L. Kirk; J. M. Knudsen; S. Larsen; M. T. Lemmon; M. B. Madsen; J. A. Magalhães; J. N. Maki; M. C. Malin; R. M. Manning; J. Matijevic; H. Y. McSween

1999-01-01

291

Comet Halley Orbit Determination by Means of the Pathfinder Data: Methods Used and Results Obtained.  

National Technical Information Service (NTIS)

Use of the pointing angle from the Soviet spacecraft Vega-1 and Vega-2 to the nucleus of the comet, derived from attitude and camera data collected onboard the two spacecraft, to determine comet orbit for Halley flyby by Giotto is described. Pathfinder re...

P. Debroeck F. Hechler P. Kristiansen A. Sukhanov

1986-01-01

292

PATHFINDER ATOMIC POWER PLANT. END CLOSURE DEVELOPMENT FOR LOW ENRICHMENT SUPERHEATER FUEL RODS  

Microsoft Academic Search

Research on a welding process for closing the ends of pathfinder fuel ; elements is reported. Optimum parameters for certain variables (amperage, weld ; travel, preheat, etc.) affecting weld quality were determined, and two modified ; end cap designs were investigated and found to reduce weld sensitivity to certain ; variables. Use of chills on the fuel tube greatly improved

R. A. Boschke; R. J. Wiggins

1963-01-01

293

Interstellar Pathfinder: A Mission to Explore the Inner Edge of the Interstellar Medium  

Microsoft Academic Search

The Interstellar Pathfinder (ISP) will explore the interstellar space surrounding our solar system and investigate its dynamic interaction with the heliosphere. A steady wind of interstellar atoms penetrates to within several AU of the Sun where ISP's instruments will analyze the composition of this unique sample of matter in detail. ISP will take global images of the distant boundary of

S. Livi; G. Gloeckler; P. Bochsler; L. Fisk; H. Funsten; J. Geiss; M. Gruntman; D. Judge; S. Krimigis; R. Lin; D. McComas; D. Mitchell; E. Moebius; E. Roelof; N. Schwadron; M. Witte; J. Woch; P. Wurz; T. Zurbuchen; D. Haggerty; R. McNutt

2002-01-01

294

PATHFINDER ATOMIC POWER PLANT. SUPERHEATED STEAM HEAT TRANSFER AND PRESSURE DROP EXPERIMENTS  

Microsoft Academic Search

Heat transfer and pressure drop in a Pathfinder nuclear superheater fuel ; element is studied by simulating tests in a long, thin annular passage, which is ; heated both internally and externally, spaced with longitudinal spacers. ; Heineman's correlation of Nusselt number L\\/D\\/sub e\\/> 60 appears to be appropriate ; for superheated steam in a thin annulus with both walls

K. F. Neusen; G. J. Kangas; N. C. Sher

1963-01-01

295

PATHFINDER ATOMIC POWER PLANT SINGLE ROD BURNOUT HEAT FLUX TESTS. Summary Report  

Microsoft Academic Search

Results of an investigation to obtain burnout data for use in design of ; the Pathfinder boiler core are presented. It was found that burnout relations ; developed for round and rectangnlar channels are not applicable to single-rod ; burnout at 600 psia. The data taken in the tests do not permit isolation of mass ; flow and inlet subcooling

K. F. Neusen; G. J. Kangas

1962-01-01

296

Hypoxia Disruption of Vertebrate CNS Pathfinding through EphrinB2 Is Rescued by Magnesium  

Microsoft Academic Search

The mechanisms of hypoxic injury to the developing human brain are poorly understood, despite being a major cause of chronic neurodevelopmental impairments. Recent work in the invertebrate Caenorhabditis elegans has shown that hypoxia causes discrete axon pathfinding errors in certain interneurons and motorneurons. However, it is unknown whether developmental hypoxia would have similar effects in a vertebrate nervous system. We

Tamara J. Stevenson; Tony Trinh; Cory Kogelschatz; Esther Fujimoto; Mark E. Lush; Tatjana Piotrowski; Cameron J. Brimley; Joshua L. Bonkowsky

2012-01-01

297

Assessing Coral Reefs on a Pacific-Wide Scale Using the Microbialization Score  

PubMed Central

The majority of the world's coral reefs are in various stages of decline. While a suite of disturbances (overfishing, eutrophication, and global climate change) have been identified, the mechanism(s) of reef system decline remain elusive. Increased microbial and viral loading with higher percentages of opportunistic and specific microbial pathogens have been identified as potentially unifying features of coral reefs in decline. Due to their relative size and high per cell activity, a small change in microbial biomass may signal a large reallocation of available energy in an ecosystem; that is the microbialization of the coral reef. Our hypothesis was that human activities alter the energy budget of the reef system, specifically by altering the allocation of metabolic energy between microbes and macrobes. To determine if this is occurring on a regional scale, we calculated the basal metabolic rates for the fish and microbial communities at 99 sites on twenty-nine coral islands throughout the Pacific Ocean using previously established scaling relationships. From these metabolic rate predictions, we derived a new metric for assessing and comparing reef health called the microbialization score. The microbialization score represents the percentage of the combined fish and microbial predicted metabolic rate that is microbial. Our results demonstrate a strong positive correlation between reef microbialization scores and human impact. In contrast, microbialization scores did not significantly correlate with ocean net primary production, local chla concentrations, or the combined metabolic rate of the fish and microbial communities. These findings support the hypothesis that human activities are shifting energy to the microbes, at the expense of the macrobes. Regardless of oceanographic context, the microbialization score is a powerful metric for assessing the level of human impact a reef system is experiencing.

McDole, Tracey; Nulton, James; Barott, Katie L.; Felts, Ben; Hand, Carol; Hatay, Mark; Lee, Hochul; Nadon, Marc O.; Nosrat, Bahador; Salamon, Peter; Bailey, Barbara; Sandin, Stuart A.; Vargas-Angel, Bernardo; Youle, Merry; Zgliczynski, Brian J.; Brainard, Russell E.; Rohwer, Forest

2012-01-01

298

Alternative stable states and phase shifts in coral reefs under anthropogenic stress.  

PubMed

Ecosystems with alternative stable states (ASS) may shift discontinuously from one stable state to another as environmental parameters cross a threshold. Reversal can then be difficult due to hysteresis effects. This contrasts with continuous state changes in response to changing environmental parameters, which are less difficult to reverse. Worldwide degradation of coral reefs, involving "phase shifts" from coral to algal dominance, highlights the pressing need to determine the likelihood of discontinuous phase shifts in coral reefs, in contrast to continuous shifts with no ASS. However, there is little evidence either for or against the existence of ASS for coral reefs. We use dynamic models to investigate the likelihood of continuous and discontinuous phase shifts in coral reefs subject to sustained environmental perturbation by fishing, nutrification, and sedimentation. Our modeling results suggest that coral reefs with or without anthropogenic stress can exhibit ASS, such that discontinuous phase shifts can occur. We also find evidence to support the view that high macroalgal growth rates and low grazing rates on macroalgae favor ASS in coral reefs. Further, our results suggest that the three stressors studied, either alone or in combination, can increase the likelihood of both continuous and discontinuous phase shifts by altering the competitive balance between corals and algae. However, in contrast to continuous phase shifts, we find that discontinuous shifts occur only in model coral reefs with parameter values near the extremes of their empirically determined ranges. This suggests that continuous shifts are more likely than discontinuous shifts in coral reefs. Our results also suggest that, for ecosystems in general, tackling multiple human stressors simultaneously maximizes resilience to phase shifts, ASS, and hysteresis, leading to improvements in ecosystem health and functioning. PMID:21661558

Fung, Tak; Seymour, Robert M; Johnson, Craig R

2011-04-01

299

Assessing coral reefs on a Pacific-wide scale using the microbialization score.  

PubMed

The majority of the world's coral reefs are in various stages of decline. While a suite of disturbances (overfishing, eutrophication, and global climate change) have been identified, the mechanism(s) of reef system decline remain elusive. Increased microbial and viral loading with higher percentages of opportunistic and specific microbial pathogens have been identified as potentially unifying features of coral reefs in decline. Due to their relative size and high per cell activity, a small change in microbial biomass may signal a large reallocation of available energy in an ecosystem; that is the microbialization of the coral reef. Our hypothesis was that human activities alter the energy budget of the reef system, specifically by altering the allocation of metabolic energy between microbes and macrobes. To determine if this is occurring on a regional scale, we calculated the basal metabolic rates for the fish and microbial communities at 99 sites on twenty-nine coral islands throughout the Pacific Ocean using previously established scaling relationships. From these metabolic rate predictions, we derived a new metric for assessing and comparing reef health called the microbialization score. The microbialization score represents the percentage of the combined fish and microbial predicted metabolic rate that is microbial. Our results demonstrate a strong positive correlation between reef microbialization scores and human impact. In contrast, microbialization scores did not significantly correlate with ocean net primary production, local chla concentrations, or the combined metabolic rate of the fish and microbial communities. These findings support the hypothesis that human activities are shifting energy to the microbes, at the expense of the macrobes. Regardless of oceanographic context, the microbialization score is a powerful metric for assessing the level of human impact a reef system is experiencing. PMID:22970122

McDole, Tracey; Nulton, James; Barott, Katie L; Felts, Ben; Hand, Carol; Hatay, Mark; Lee, Hochul; Nadon, Marc O; Nosrat, Bahador; Salamon, Peter; Bailey, Barbara; Sandin, Stuart A; Vargas-Angel, Bernardo; Youle, Merry; Zgliczynski, Brian J; Brainard, Russell E; Rohwer, Forest

2012-09-07

300

Atlantic coral reefs: the transplantation alternative  

Microsoft Academic Search

Although all of the world’s coral reef regions have suffered degradation due to direct and indirect human influences, only\\u000a the Western Atlantic reefs have declined to the extent that their continued existence appears to be in jeopardy. Of a once\\u000a flourishing reef system, only about 10% is still alive and it is depauperate in terms of the food web diversity

John C. Briggs

2009-01-01

301

Oyster Reefs as Complex Ecological Systems  

Microsoft Academic Search

Aggregations of suspension-feeding organisms like oyster reefs, mussel beds and worm reefs are prominent systems in coastal\\u000a environments. The fundamental properties of these systems are reviewed and indicate that they are complex systems that are\\u000a highly optimized and evolutionarily selected for high productivity. Such systems are unstable when faced with a never experienced\\u000a situation. In the case of oyster reefs,

Richard Dame

302

Climate change and coral reef connectivity  

Microsoft Academic Search

This review assesses and predicts the impacts that rapid climate change will have on population connectivity in coral reef\\u000a ecosystems, using fishes as a model group. Increased ocean temperatures are expected to accelerate larval development, potentially\\u000a leading to reduced pelagic durations and earlier reef-seeking behaviour. Depending on the spatial arrangement of reefs, the\\u000a expectation would be a reduction in dispersal

P. L. Munday; J. M. Leis; J. M. Lough; C. B. Paris; M. J. Kingsford; M. L. Berumen; J. Lambrechts

2009-01-01

303

Interview with Grace Reef by Diane Dewhirst  

Microsoft Academic Search

Biographical NoteGrace Reef grew up in Portland, Maine, with her father, Norman Reef, an attorney, and her mother, Patricia Reef. In 1974, as a twelve-year-old, she was the first female Little League baseball player, having sued to integrate girls into the program. She first heard of Senator Mitchell when he ran for governor in 1974. She attended Colby College, graduating

Grace Reef

2009-01-01

304

Coral reef ecosystems and anthropogenic climate change  

Microsoft Academic Search

Coral reef ecosystems are among the most biologically diverse ecosystems on the planet. In addition to their value in terms\\u000a of biodiversity, coral reefs provide food and resources for over 500 million people. Despite their importance, coral reefs\\u000a are declining at a rapid rate (1–2% per year) as a result of a range of local (e.g., overexploitation of fisheries, declining\\u000a water

Ove Hoegh-Guldberg

2011-01-01

305

Microbial photosynthesis in coral reef sediments (Heron Reef, Australia)  

NASA Astrophysics Data System (ADS)

We investigated microphytobenthic photosynthesis at four stations in the coral reef sediments at Heron Reef, Australia. The microphytobenthos was dominated by diatoms, dinoflagellates and cyanobacteria, as indicated by biomarker pigment analysis. Conspicuous algae firmly attached to the sand grains (ca. 100 ?m in diameter, surrounded by a hard transparent wall) were rich in peridinin, a marker pigment for dinoflagellates, but also showed a high diversity based on cyanobacterial 16S rDNA gene sequence analysis. Specimens of these algae that were buried below the photic zone exhibited an unexpected stimulation of respiration by light, resulting in an increase of local oxygen concentrations upon darkening. Net photosynthesis of the sediments varied between 1.9 and 8.5 mmol O 2 m -2 h -1 and was strongly correlated with Chl a content, which lay between 31 and 84 mg m -2. An estimate based on our spatially limited dataset indicates that the microphytobenthic production for the entire reef is in the order of magnitude of the production estimated for corals. Photosynthesis stimulated calcification at all investigated sites (0.2-1.0 mmol Ca 2+ m -2 h -1). The sediments of at least three stations were net calcifying. Sedimentary N 2-fixation rates (measured by acetylene reduction assays at two sites) ranged between 0.9 to 3.9 mmol N 2 m -2 h -1 and were highest in the light, indicating the importance of heterocystous cyanobacteria. In coral fingers no N 2-fixation was measurable, which stresses the importance of the sediment compartment for reef nitrogen cycling.

Werner, Ursula; Blazejak, Anna; Bird, Paul; Eickert, Gabriele; Schoon, Raphaela; Abed, Raeid M. M.; Bissett, Andrew; de Beer, Dirk

2008-03-01

306

Onondage pinnacle reefs in New York State  

SciTech Connect

Onondaga pinnacle reefs, part of the Onondaga Formation, developed in an epeiric setting of the lowermost Middle Devonian (Eifelian). The reefs were initiated as coral-crinoidal mounds in the Edgecliff Member of the formation. Whereas most Devonian reefs are composed of rugose corals. Coral is the predominant kind of fossil, followed by crinoids, brachiopods, mollusks, undifferentiated skeletal debris, and possible sponges. The initial mineralogy of the corals is inferred to have been calcite. The porosity of these reefs is almost unique among reef reservoirs. most reefs produce from secondary or diagenetic porosity; by contrast Onondaga reefs display primary intracoralline or framework porosity. Between framework builders and/or skeletal particles cryptocrystalline/microcrystalline cement fills pores. As observed in modern reefs this kind of cement resembles micrite, but probable formed as high-magnesian calcite in a high-energy setting. Syntaxial or rim cement common lines crinoid particles. Some of these pinnacle reefs, formerly gas producers, are presently under development as gas-storage reservoirs.

Friedman, G.M. [Brooklyn College and Graduate School of CUNY, Brooklyn, NY (United States)

1995-09-01

307

Satellite Remote Sensing of Coral Reefs  

NSDL National Science Digital Library

Coral reefs are one of the most endangered ecosystems as coral reef coverage has declined dramatically in the past three decades. In recent years, satellite remote sensing has become a popular and effective mapping tool for ecological studies, especially in marine science. This lesson plan designed for high school science students demonstrates how marine scientists use satellite remote sensing to gather detailed information about coral reefs worldwide. An in-depth review of both remote sensing and coral reefs is also included in this article.

Palandro, David; Muller-Karger, Frank; Kusek, Kristen; Thoms, Kristin; Greely, Teresa

2005-09-01

308

Impacts of Artificial Reefs on Surrounding Ecosystems  

NASA Astrophysics Data System (ADS)

Artificial reefs are becoming a popular biological and management component in shallow water environments characterized by soft seabed, representing both important marine habitats and tools to manage coastal fisheries and resources. An artificial reef in the marine environment acts as an open system with exchange of material and energy, altering the physical and biological characteristics of the surrounding area. Reef stability will depend on the balance of scour, settlement, and burial resulting from ocean conditions over time. Because of the unstable nature of sediments, they require a detailed and systematic investigation. Acoustic systems like high-frequency multibeam sonar are efficient tools in monitoring the environmental evolution around artificial reefs, whereas water turbidity can limit visual dive and ROV inspections. A high-frequency multibeam echo sounder offers the potential of detecting fine-scale distribution of reef units, providing an unprecedented level of resolution, coverage, and spatial definition. How do artificial reefs change over time in relation to the coastal processes? How accurately does multibeam technology map different typologies of artificial modules of known size and shape? How do artificial reefs affect fish school behavior? What are the limitations of multibeam technology for investigating fish school distribution as well as spatial and temporal changes? This study addresses the above questions and presents results of a new approach for artificial reef seafloor mapping over time, based upon an integrated analysis of multibeam swath bathymetry data and geoscientific information (backscatter data analysis, SCUBA observations, physical oceanographic data, and previous findings on the geology and sedimentation processes, integrated with unpublished data) from Senigallia artificial reef, northwestern Adriatic Sea (Italy) and St. Petersburg Beach Reef, west-central Florida continental shelf. A new approach for observation of fish aggregations associated with Senigallia reef based on the analysis of multibeam backscatter data in the water column is also explored. The settlement of the reefs and any terrain change are investigated over time providing a useful description of the local hydrodynamics and geological processes. All the artificial structures (made up by water-based concrete for Senigallia reef and mainly steel for St. Petersburg Beach reef) are identified and those showing substantial horizontal and/or vertical movements are analyzed in detail. Most artificial modules of Senigallia reef are not intact and scour signatures are well depicted around them, indicating reversals of the local current. This is due to both the wind pattern and to the quite close arrangement of the reef units that tend to deflect the bottom flow. As regards to the St. Petersburg Beach reef, all the man-made steel units are still in their upright position. Only a large barge shows a gradual collapse of its south side, and presents well-developed scouring at its east-northeast side, indicating dominant bottom flow from west-southwest to east-northeast. While an overall seafloor depth shallowing of about 0.30 m from down-current deposits was observed for Senigallia reef, an overall deepening of about 0.08 m due to scour was observed at the St. Petersburg Beach reef. Based on the backscatter data interpretation, surficial sediments are coarser in the vicinities of both artificial reefs than corresponding surrounding sediments. Scouring reveals this coarser layer underneath the prevalent mud sediment at Senigallia reef, and the predominant silt sediment at St. Petersburg Beach reef. In the ten years of Senigalia reef study, large-scale variations between clay and silt appear to be directly linked to large flood events that have occurred just prior to the change. As regards the water column investigation, acoustic backscatter from fish aggregations gives detailed information on their morphology and spatial distribution. In addition, relative fish biomass estimates can be extrapolated. Results suggest that most of

Manoukian, Sarine

309

Hypoxia Disruption of Vertebrate CNS Pathfinding through EphrinB2 Is Rescued by Magnesium  

PubMed Central

The mechanisms of hypoxic injury to the developing human brain are poorly understood, despite being a major cause of chronic neurodevelopmental impairments. Recent work in the invertebrate Caenorhabditis elegans has shown that hypoxia causes discrete axon pathfinding errors in certain interneurons and motorneurons. However, it is unknown whether developmental hypoxia would have similar effects in a vertebrate nervous system. We have found that developmental hypoxic injury disrupts pathfinding of forebrain neurons in zebrafish (Danio rerio), leading to errors in which commissural axons fail to cross the midline. The pathfinding defects result from activation of the hypoxia-inducible transcription factor (hif1) pathway and are mimicked by chemical inducers of the hif1 pathway or by expression of constitutively active hif1?. Further, we found that blocking transcriptional activation by hif1? helped prevent the guidance defects. We identified ephrinB2a as a target of hif1 pathway activation, showed that knock-down of ephrinB2a rescued the guidance errors, and showed that the receptor ephA4a is expressed in a pattern complementary to the misrouting axons. By targeting a constitutively active form of ephrinB2a to specific neurons, we found that ephrinB2a mediates the pathfinding errors via a reverse-signaling mechanism. Finally, magnesium sulfate, used to improve neurodevelopmental outcomes in preterm births, protects against pathfinding errors by preventing upregulation of ephrinB2a. These results demonstrate that evolutionarily conserved genetic pathways regulate connectivity changes in the CNS in response to hypoxia, and they support a potential neuroprotective role for magnesium.

Stevenson, Tamara J.; Trinh, Tony; Kogelschatz, Cory; Fujimoto, Esther; Lush, Mark E.; Piotrowski, Tatjana; Brimley, Cameron J.; Bonkowsky, Joshua L.

2012-01-01

310

Nocturnal relocation of adult and juvenile coral reef fishes in response to reef noise  

NASA Astrophysics Data System (ADS)

Juvenile and adult reef fishes often undergo migration, ontogenic habitat shifts, and nocturnal foraging movements. The orientation cues used for these behaviours are largely unknown. In this study, the use of sound as an orientation cue guiding the nocturnal movements of adult and juvenile reef fishes at Lizard Island, Great Barrier Reef was examined. The first experiment compared the movements of fishes to small patch reefs where reef noise was broadcast, with those to silent reefs. No significant responses were found in the 79 adults that were collected, but the 166 juveniles collected showed an increased diversity each morning on the reefs with broadcast noise, and significantly greater numbers of juveniles from three taxa (Apogonidae, Gobiidae and Pinguipedidae) were collected from reefs with broadcast noise. The second experiment compared the movement of adult and juvenile fishes to reefs broadcasting high (>570 Hz), or low (<570 Hz) frequency reef noise, or to silent reefs. Of the 122 adults collected, the highest diversity was seen at the low frequency reefs; and adults from two families (Gobiidae and Blenniidae) preferred these reefs. A similar trend was observed in the 372 juveniles collected, with higher diversity at the reefs with low frequency noises. This preference was seen in the juvenile apogonids; however, juvenile gobiids were attracted to both high and low sound treatments equally, and juvenile stage Acanthuridae preferred the high frequency noises. This evidence that juvenile and adult reef fishes orientate with respect to the soundscape raises important issues for management, conservation and the protection of sound cues used in natural behaviour.

Simpson, S. D.; Jeffs, A.; Montgomery, J. C.; McCauley, R. D.; Meekan, M. G.

2008-03-01

311

Conservation, precaution, and Caribbean reefs  

NASA Astrophysics Data System (ADS)

Some authors argue that overfishing is an important reason that reef corals have declined in recent decades. Their reasoning is that overfishing removes herbivores, releasing macroalgae to overgrow and kill the corals. The evidence suggests, however, that global climate change and emergent marine diseases make a far greater contribution to coral mortality, and that macroalgae generally grow on the exposed skeletal surfaces of corals that are already dead. Macroalgal dominance, therefore, is an effect rather than a cause of coral mortality. Marine protected areas (MPAs), which are usually established to protect stocks of reef fish, foster populations of herbivorous fish under at least some circumstances. Increased herbivory can reduce algal cover, potentially accelerating the recovery of coral populations inside MPAs; however, establishing MPAs will have only a limited impact on coral recovery unless policymakers confront the accelerating negative effects of the global-scale sources of coral mortality.

Aronson, Richard B.; Precht, William F.

2006-08-01

312

Biogeochemistry of inter-reef sediments on the northern and central Great Barrier Reef  

Microsoft Academic Search

The deposition and cycling of carbon and nitrogen in carbonate sediments located between coral reefs on the northern and central\\u000a sections of the Great Barrier Reef were examined. Rates of mass sediment accumulation ranged from 1.9 kg m?2 year?1 (inshore reefs) to 2.1–4.9 kg m?2 year?1 (between mid-shelf reefs); sedimentation was minimal off outer-shelf reefs. Rates of total organic carbon decomposition ranged\\u000a from 1.7 to 11.4 mol C m?2 year?1

D. M. Alongi; L. A. Trott; J. Pfitzner

2008-01-01

313

Bioindication in coral reef ecosystems.  

PubMed

The concept of bioindication in the sense of the use of organisms for detecting environmental stress has been employed in coral reef conservation and management for the past several years. Important tools are coral growth rates and various community parameters, notably hard coral cover. The present need is the optimal coordination of international efforts for the earliest possible institution of an effective monitoring system. PMID:2884790

Yap, H T

1986-01-01

314

A novel reef coral symbiosis  

Microsoft Academic Search

Reef building corals form close associations with unicellular microalgae, fungi, bacteria and archaea, some of which are symbiotic\\u000a and which together form the coral holobiont. Associations with multicellular eukaryotes such as polychaete worms, bivalves\\u000a and sponges are not generally considered to be symbiotic as the host responds to their presence by forming physical barriers\\u000a with an active growth edge in

O. Pantos; J. C. Bythell

2010-01-01

315

Simulation and template generation for LISA Pathfinder Data Analysis  

NASA Astrophysics Data System (ADS)

The LISA PathFinder (LPF) mission is a technology demonstration mission which aims at testing a number of critical technical challenges that the future LISA (Gravitational wave detection in space) mission will face: LPF can be seen as a complex laboratory experiment in space. It is therefore critical to be able to define which measurements and which actuations will be applied during the scientific part of the mission. The LISA Technology Package (LTP), part of ESA's hardware contribution to LPF, outlines hence the importance of developing an appropriate simulation tool in order to test these strate-gies before launch and to analyse the dynamical behaviour of the system during the mission. The detailed model of the simulation can be used in an off-line mode for further planning: cor-rect estimation of timeline priorities, risk factors, duty cycles, data analysis readiness. The Lisa Technology Package Data Analysis (LTPDA) team has developed an object-oriented MATLAB toolbox for general case of data analysis needs. However, to meet specific needs of LPF mis-sion, a template generation tool has been developed. It provides a recognizable data pattern, avoiding the risk of missing the model during mission's analysis. The aim of the template generator tool is to provide tools to analyse LTP system modeled in State Space Model (SSM). The SSM class, the aim of this poster, includes this tools within the LTPDA toolbox. It can be used to generate the time-domain response for any given actuation and/or noise, the frequency response using bode diagrams and the steady state of the system. It allows the user to project noises on system outputs to get spectra of outputs for given input noises spectra. This class is sufficiently general to be used with a variety of systems once the SSM of the system is provided in the library. Furthermore, one of the main objectives of the data analysis for LPF (the estimation of different parameters of the system), can be achieved by a new generation of estimators based on Kalman filtering, an efficient recursive Bayesian estimator implemented within this class. To validate performances of this template generator tool, the library of models was used to simulate LTP for specific test cases and has been compared to "experimentally simulated" data provided by the STOC (ESA's Science and Technology Operations Centre) LPF simulator. The STOC has the leading role in the analysis of the mission data and the STOC LPF simulator is considered as the reference to check and validate results against because of its mission-mimicking abilities. This presentation documents the work performed for the implementation of this template generator based on State-space models to simulate LPF. We report the performance of this tool and the results obtained when comparing it's outputs to those produced by the STOC simulator.

Rais, Boutheina; Grynagier, Adrien; Diaz-Aguiló, Marc; Armano, Michele

316

Coral reef evolution on rapidly subsiding margins  

NASA Astrophysics Data System (ADS)

A series of well-developed submerged coral reefs are preserved in the Huon Gulf (Papua New Guinea) and around Hawaii. Despite different tectonics settings, both regions have experienced rapid subsidence (2-6 m/ka) over the last 500 ka. Rapid subsidence, combined with eustatic sea-level changes, is responsible for repeated drowning and backstepping of coral reefs over this period. Because we can place quantitative constraints on these systems (i.e., reef drowning age, eustatic sea-level changes, subsidence rates, accretion rates, basement substrates, and paleobathymetry), these areas represent unique natural laboratories for exploring the roles of tectonics, reef accretion, and eustatic sea-level changes in controlling the evolution of individual reefs, as well as backstepping of the entire system. A review of new and existing bathymetric, radiometric, sedimentary facies and numerical modeling data indicate that these reefs have had long, complex growth histories and that they are highly sensitive, recording drowning not only during major deglaciations, but also during high-frequency, small-amplitude interstadial and deglacial meltwater pulse events. Analysis of five generalized sedimentary facies shows that reef drowning is characterized by a distinct biological and sedimentary sequence. Observational and numerical modeling data indicate that on precessional (20 ka) and sub-orbital timescales, the rate and amplitude of eustatic sea-level changes are critical in controlling initiation, growth, drowning or sub-aerial exposure, subsequent re-initiation, and final drowning. However, over longer timescales (> 100-500 ka) continued tectonic subsidence and basement substrate morphology influence broad scale reef morphology and backstepping geometries. Drilling of these reefs will yield greatly expanded stratigraphic sections compared with similar reefs on slowly subsiding, stable and uplifting margins, and thus they represent a unique archive of sea-level and climate changes, as well as a record of the response of coral reefs to these changes over the last six glacial cycles.

Webster, Jody M.; Braga, Juan Carlos; Clague, David A.; Gallup, Christina; Hein, James R.; Potts, Donald C.; Renema, Willem; Riding, Robert; Riker-Coleman, Kristin; Silver, Eli; Wallace, Laura M.

2009-03-01

317

Pathfinder Landing Site: Alternatives to Catastrophic Floods and An Antarctic Ice-Flow Analog for Outflow Channels on Mars.  

National Technical Information Service (NTIS)

The Pathfinder spacecraft landed successfully at the mouth of the outflow channels Ares and Tiu Valles, returning a wealth of information about the surrounding landscape. One goal of the mission was to ascertain that catastrophic floods formed the outflow...

B. K. Lucchitta

1998-01-01

318

Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve  

NSDL National Science Digital Library

Describes the unique Northwestern Hawaiian Islands (NWHI) Ecosystem Reserve. Provides resources focused on NWHI coral reef ecosystems, and introductions to reef research, management and protection activities. Educational outreach includes: teacher workshops; student activities, and a Discovery Center in Hilo, Hawaii that features exhibits and activities for schools and the public.

319

Silurian pinnacle reefs of the Canadian Arctic  

SciTech Connect

Pinnacle reefs are commonly an attractive target for oil exploration because they are usually porous carbonate bodies entombed in impervious, deep-water shales that provide both the source and the seal for hydrocarbons. Silurian pinnacle reefs, the first described in the Canadian Arctic Archipelago, are exposed on Ellesmere and Devon Islands. Two main reef trends occur, one of early middle Llandovery to middle Ludlow age and a second of middle Ludlow to Late Silurian or Early Devonian age. Reefs of both phases contain lime mudstone cores: some are stromatactoid-rich and others consist predominantly of microbialite-rich lime mudstone or microbial boundstone. Facies sequences of both reef phases show evidence of upward-shallowing overall, but, in the older reefs, isochronous capping facies are dominated either by coral-mirian or by stromatoporoid boundstone and floatstone. This difference perhaps reflects variation in wave stress and apparent ability of a few corals,thickly encrusted by or associated with microbial boundstone and skeletal algae, to withstand greater wave energy than a stromatoporoid-coral-rich reef community. These reefs constitute one of the bright prospects of hydrocarbon exploration in rocks of the Franklinian succession. 43 refs., 9 figs.

De Freitas, T.A.; Dixon, O.A. (Univ. of Ottawa, Ontario (Canada)); Mayr, U. (Institute of Sedimentary and Petroleum Geology, Alberta (Canada))

1993-04-01

320

Artificial Reefs--A Coastal Classroom Project.  

ERIC Educational Resources Information Center

Discusses the construction of artificial reefs for such uses as commercial fishing and recreational boating. Describes a class project in which students construct a small artificial reef and observe the changes over time in terms of temperature, salinity, flora and fauna. (TW)

Dindo, John J.

1986-01-01

321

Artificial Reefs--A Coastal Classroom Project.  

ERIC Educational Resources Information Center

|Discusses the construction of artificial reefs for such uses as commercial fishing and recreational boating. Describes a class project in which students construct a small artificial reef and observe the changes over time in terms of temperature, salinity, flora and fauna. (TW)|

Dindo, John J.

1986-01-01

322

Phosphorus and nitrogen in coral reef sediments  

Microsoft Academic Search

The occurrence of P and N in the sediments has been investigated on Davies Reef in the central region of the Great Barrier Reef Complex. Concentrations of inorganic P and N in the water were typical of nutrient-depleted tropical surface water. Carbonate sediments were found to contain a uniform pool of P (300 ppm by wt), principally in the form

BARRIE ENTSCH; KEVIN G. BOTO; ROBIN G. SIM; JOHN T. WELLINGTON

1983-01-01

323

Ancient reef ecosystem expansion and collapse  

Microsoft Academic Search

Platform carbonate and, particularly, reef ecosystem development (with reefs representing the acme of carbonate platform growth) were highly cyclical in early to mid Paleozoic time, especially in relation to known or postulated times of global warming or cooling. These cycles do not appear to correspond to postulated 26 Ma rhythms seen in diversity patterns, nor were they regular. There were

P. Copper

1994-01-01

324

Numerical Modeling of Atoll Reef Harbors.  

National Technical Information Service (NTIS)

The effect of the shape of a harbor cut through a reef on mitigating waves from the deep ocean was studied using a shallow water, nonlinear, long wave code called SWAN. A significant amount of the wave energy is dissipated over the reef regardless of the ...

C. L. Mader M. Vitousek S. Lukas

1986-01-01

325

Preliminary observations on coral reef plankton  

Microsoft Academic Search

ABSTBRCT Plankton collections near coral reefs were made by hand-towing nets while swimming and by using a suction device for sampling caves. Plankton in sheltered areas was con- sidcrably different from that in nonsheltered areas; some plankton forms maintained position near coral reefs, indicating that the terms planktonic and epibenthic may represent extremes of a behavior continuum. Copepods were observed

ALAN R. EMERY

1968-01-01

326

Artificial Reefs and Mass Marine Ecotourism  

Microsoft Academic Search

Deploying artificial reefs on the seabed has become popular in diving management. This practice has been advocated as a means towards meeting both ecological concerns and recreational divers’ demands for diversification and themed experiences. Nevertheless, the perceptions of the user community itself – the scuba divers – regarding the establishment of artificial reefs have received only limited attention in the

Amir Shani; Omer Polak; Nadav Shashar

2011-01-01

327

Artificial Reefs and Mass Marine Ecotourism  

Microsoft Academic Search

Deploying artificial reefs on the seabed has become popular in diving management. This practice has been advocated as a means towards meeting both ecological concerns and recreational divers’ demands for diversification and themed experiences. Nevertheless, the perceptions of the user community itself – the scuba divers – regarding the establishment of artificial reefs have received only limited attention in the

Amir Shani; Omer Polak; Nadav Shashar

2012-01-01

328

Bathymetric distribution of foraminifera in Jamaican reef environments  

SciTech Connect

Recent foraminifera inhabiting Jamaican north-coast fringing reefs display variations in distributional patterns that are related to bathymetry and reef morphology. Sediment samples containing foraminifera were collected along a profile that traversed the back reef (depth 1-2 m), fore-reef terrace (3-15 m), fore-reef escarpment (15-27 m), fore-reef slope (30-55 m), and upper deep fore reef (70 m). Approximately 150 species distributed among 80 genera were identified from the samples. Preliminary analyses indicate that diversity values (S, H') are lowest on the fore-reef terrace (79, 3.0, respectively), increase similarly in back-reef and fore-reef escarpment and slope settings (93, 3.4), and are highest on the deep fore reef (109, 3.7). Larger groupings (suborders) exhibit distinct bathymetric trends with miliolids occurring more commonly in back-reef (comprising 51% of the fauna) than in fore-reef (28%) zones, whereas agglutinated and planktonic species occur more commonly in deeper reef (> 15 m, 9% and 4%, respectively) than in shallower reef zones (< 15 m, 3%, and 0.5%, respectively). Among the more common species Amphistegina gibbosa (Rotolina) is much more abundant in fore-reef (3%) environments, and Sorites marginalis (Miliolina) occurs almost exclusively in the back reef, where it comprises 5.5% of the fauna. Q-mode cluster analysis, involving all species collected, enabled the delineation of back-reef, shallow fore-reef, and deeper fore-reef biofacies, also indicating the potential utility of foraminiferal distributions in detailed paleoenvironment interpretations of ancient reef settings.

Martin, R.E.; Liddell, W.D.

1985-02-01

329

The National Snow and Ice Data Center's Polar Pathfinder Sampler CD-ROM  

NASA Astrophysics Data System (ADS)

The NOAA/NASA Pathfinder Program is designed to facilitate user access to earth science data sets which address global change concerns. The Polar Pathfinders, a subgroup of the Pathfinder Program, addresses the comparison of parameters from different data sets with a common projection (the NSIDC Equal-Area Scalable Earth-Grid (EASE-Grid)), file naming conventions, and validation conventions. This ensures that consistently processed data sets are available to the cryospheric science community, for comparing and contrasting. The National Snow and Ice Data Center (NSIDC) has produced a CD-ROM called, "Polar Pathfinder Sampler: Combined AVHRR, SMMR-SSM/I, and TOVS Time Series and Samples." This CD-ROM includes sample data, time-series visualizations, and browse products, for temporal and spatial subsets of the AVHRR, SMMR-SSM/I and TOVS data sets, to illustrate the types of products available for the various data sets. Also included on this CD-ROM is the P-Cube, a multidimensional structure combining arctic SSM/I, AVHRR and TOVS data. The data highlighted on this CD-ROM serve a wide range of polar climate research applications, but are of particular interest to researchers working on large-scale atmospheric changes, sea ice modeling, and surface heat and mass balance studies. AVHRR products for both hemispheres, at 1.25 and 5 km resolutions, include calibrated channel data, surface broadband albedo, surface temperature, and ancillary data so that users can apply algorithms of their choice to calculate albedo and surface temperature. SSM/I brightness temperature data and time files are included, in each of three projections: Northern and Southern Hemispheres and an equatorial cylindrical projection. TOVS parameters derived from arctic (poleward of 60 degrees north latitude) radiances include atmospheric temperature profiles, water vapor, surface temperature, total effective cloud fraction, cloud top pressure and temperature, turning angle between geostrophic wind and surface stress over ice, emissivity, boundary layer stratification and geostrophic drag coefficient. The P-Cube combines arctic SSM/I, AVHRR and TOVS data, all mapped to a 100 km resolution EASE-Grid, thereby facilitating study of polar processes and interactions among them using data from multiple sensors. The current prototype version of the P-Cube includes the most important parameters from the three Polar Pathfinders noted above, and the temporal coverage extends from 1 January 1988 to 31 December 1989. Future versions of the P-Cube will have expanded temporal and spatial coverage, as well as additional parameters. Featured data products and tools on the Polar Pathfinder Sampler CD-ROM will be presented.

Thrasher Hybl, T. L.; Khalsa, S. S.; Holm, M.

2001-05-01

330

Habitat effects and sampling bias on Phanerozoic reef distribution  

Microsoft Academic Search

Incomplete preservation, heterogeneous geographic sampling, uncertainties in palaeogeographic reconstructions and inconsistencies of reef definitions bias global reef patterns observed in the geological record. This sampling bias is added to a biological habitat area effect, which is thought to be of paramount importance for modern reefs. To evaluate the importance of sampling bias of ancient reefs, I first tested the habitat

Wolfgang Kiessling

2005-01-01

331

Artificial reef debate: Habitat enhancement or waste disposal?  

Microsoft Academic Search

Modern artificial reef projects are taking novel approaches to fishery habitat construction. Development of these reefs may involve the use of obsolete oil platforms, concrete blocks mixed with municipal incinerator ash, or even automobile tires. Because modern reef designs make use of materials heavily regulated by ocean dumping agreements and statutes, concern arises as to the effects of these reefs

John M. Macdonald

1994-01-01

332

Wave Forced Normal Modes on Fringing Reefs  

NASA Astrophysics Data System (ADS)

In an effort to assess wave-driven coastal inundation at the shoreline of fringing reefs, pressure and current observations were collected at reefs on Guam (Ipan) and Oahu, Hawaii (Mokuleia) as part of the PILOT (Pacific Island Land-Ocean Typhoon) experiment. Similar to dissipative sandy beaches, nearshore surface elevation at both reefs is dominated by energy in the infragravity frequency band. Coherent infragravity oscillations across the reef tend to occur at discrete frequencies and with standing wave cross-shore structures that are consistent with open basin resonant modes. The modes are forced by swell wave groups, similar to a time-dependent setup. The resonant modes are most apparent during energetic wave events, in part because wave setup over the reef increases the low mode resonant frequencies to a range that is conducive to wave group forcing. Evidence of the excitation of resonant modes during tropical storm Man-Yi at Ipan, Guam is presented.

Pequignet, A. N.; Becker, J. M.; Merrifield, M. M.; Aucan, J.

2008-12-01

333

Edgecliff reefs - Devonian temperate water carbonate deposition  

SciTech Connect

The Middle Devonian Edgecliff Member of the Onondaga Formation in New York and Ontario, Canada, is a coral-rich, reefy,' crinoidal grainstone/packstone. The reefs contain only rare stromatoporoids and are devoid of algae, having been constructed by a fauna of mound and thicket-forming branching colonial rugosans, and large sheet favositids that populated grainstone/packstone flank beds and banks. Despite the restricted fauna, the reefs display a variety of growth patterns. Rugosan mounds range in size from 2-3 m diameter by 1 m thick, up to 230 m diameter by 15 m thick. Composite structures consist of interbedded rugosan buildups and packstone/grainstone flanks, ranging from shield-shaped reefs (240 m diameter by 6 m thick) in which the rugosans occur only as thickets, to pinnacle reefs (up to 3 km diameter by 60 m thick) in which rugosan mounds are interbedded with crinoidal flanks. Geographic distribution of these reef types and analysis of surrounding facies suggests that reef growth pattern was controlled by water depth and local rate of subsidence. Despite superfacial resemblance to modern deep water ahermatypic coral mounds and thickets, abundant coral breakage and overturning, and erosion of at least one reef core during an intermediate stage of reef growth supports a shallow water origin of these reefs. It is suggested that the Edgecliff and its reefs represent an example of Devonian cool water carbonate deposition, a hypothesis supported by a trend of increasing stromatoporoid abundance westwards across New York (in the direction of the paleo-equator).

Wolosz, T.H. (State Univ. of New York, Plattsburgh (United States))

1991-03-01

334

Patterns in the distribution of the crinoid community at Davies Reef on the central Great Barrier Reef  

Microsoft Academic Search

The crinoid community of Davies Reef, a midshelf reef in the central Great Barrier Reef, was systematically sampled in all major crinoid habitats. A total of 294 individuals of 27 species-level taxa was found in 25 sites across the reef. Of these 27 taxa, 20 were confidently assigned to known species. The 25 sitesx27 taxa matrix was subjected to an

R. H. Bradbury; R. E. Reichelt; D. L. Meyer; R. A. Birtles

1987-01-01

335

Estimation of photosynthesis and calcification rates at a fringing reef by accounting for diurnal variations and the zonation of coral reef communities on reef flat and slope: a case study for the Shiraho reef, Ishigaki Island, southwest Japan  

Microsoft Academic Search

Seven coral reef communities were defined on Shiraho fringing reef, Ishigaki Island, Japan. Net photosynthesis and calcification\\u000a rates were measured by in situ incubations at 10 sites that included six of the defined communities, and which occupied most\\u000a of the area on the reef flat and slope. Net photosynthesis on the reef flat was positive overall, but the reef flat

T. Nakamura; T. Nakamori

2009-01-01

336

Regulation of axonal outgrowth and pathfinding by integrin-ECM interactions  

PubMed Central

Developing neurons use a combination of guidance cues to assemble a functional neural network. A variety of proteins immobilized within the extracellular matrix (ECM) provide specific binding sites for integrin receptors on neurons. Integrin receptors on growth cones associate with a number of cytosolic adaptor and signaling proteins that regulate cytoskeletal dynamics and cell adhesion. Recent evidence suggests that soluble growth factors and classic axon guidance cues may direct axon pathfinding by controlling integrin-based adhesion. Moreover, since classic axon guidance cues themselves are immobilized within the ECM and integrins modulate cellular responses to many axon guidance cues, interactions between activated receptors modulate cell signals and adhesion. Ultimately, growth cones control axon outgrowth and pathfinding behaviors by integrating distinct biochemical signals to promote the proper assembly of the nervous system. In this review, we discuss our current understanding how ECM proteins and their associated integrin receptors control neural network formation.

Myers, Jonathan P.; Santiago-Medina, Miguel; Gomez, Timothy M.

2011-01-01

337

Pathfinding of corticothalamic axons relies on a rendezvous with thalamic projections  

PubMed Central

Summary Major outputs of the neocortex are conveyed by corticothalamic axons (CTA), which form reciprocal connections with thalamocortical axons, and corticosubcerebral axons (CSA) headed to more caudal parts of the nervous system. Previous findings establish that transcriptional programs define cortical neurons identity and suggest that CTA and thalamic axons may guide each other, but the mechanisms governing CTA versus CSA pathfinding remain elusive. Here, we show that thalamocortical axons are required to guide pioneer CTA away from a default CSA-like trajectory. This process relies on a hold in the progression of cortical axons, or waiting period, during which thalamic projections navigate towards cortical axons. At the molecular level, Sema3E/PlexinD1 signaling in pioneer cortical neurons mediates a “waiting signal” required to orchestrate the mandatory meeting with reciprocal thalamic axons. Our study reveals that temporal control of axonal progression contributes to spatial pathfinding of cortical projections and opens novel perspectives on brain wiring.

Deck, M.; Lokmane, L.; Chauvet, S.; Mailhes, C.; Keita, M.; Niquille, M.; Yoshida, M.; Yoshida, Y.; Lebrand, C.; Mann, F.; Grove, E.A.; Garel, S.

2013-01-01

338

Pathfinding of corticothalamic axons relies on a rendezvous with thalamic projections.  

PubMed

Major outputs of the neocortex are conveyed by corticothalamic axons (CTAs), which form reciprocal connections with thalamocortical axons, and corticosubcerebral axons (CSAs) headed to more caudal parts of the nervous system. Previous findings establish that transcriptional programs define cortical neuron identity and suggest that CTAs and thalamic axons may guide each other, but the mechanisms governing CTA versus CSA pathfinding remain elusive. Here, we show that thalamocortical axons are required to guide pioneer CTAs away from a default CSA-like trajectory. This process relies on a hold in the progression of cortical axons, or waiting period, during which thalamic projections navigate toward cortical axons. At the molecular level, Sema3E/PlexinD1 signaling in pioneer cortical neurons mediates a "waiting signal" required to orchestrate the mandatory meeting with reciprocal thalamic axons. Our study reveals that temporal control of axonal progression contributes to spatial pathfinding of cortical projections and opens perspectives on brain wiring. PMID:23395374

Deck, Marie; Lokmane, Ludmilla; Chauvet, Sophie; Mailhes, Caroline; Keita, Maryama; Niquille, Mathieu; Yoshida, Michio; Yoshida, Yutaka; Lebrand, Cécile; Mann, Fanny; Grove, Elizabeth A; Garel, Sonia

2013-02-01

339

Review of the trajectory and atmospheric structure reconstruction for Mars Pathfinder  

NASA Astrophysics Data System (ADS)

Mars Pathfinder landed on Mars on July 4, 1997. It used a novel deceleration procedure, consisting of a hypersonic aeroshell, a transonic parachute, retro-rockets, and airbags, to reach the surface safely. Its aerodynamic properties passively maintained a near-zero angle of attack throughout its entry. There were no gyroscopes to monitor attitude. Several different trajectory reconstructions have been based on the assumptions that accelerations along its symmetry axis are directed along its flight path and that accelerations in other directions are insignificant. The aerodynamics of Pathfinder once its parachute opened are still not well-understood and the available observations are probably not sufficient to improve matters significantly in the future.

Withers, Paul; Towner, Martin; Hathi, Brijen; Zarnecki, John

2004-02-01

340

Assessing the effects of non-point source pollution on American Samoa's coral reef communities.  

PubMed

Surveys were completed on Tutuila Island, American Samoa, to characterize reef development and assess the impacts of non-point source pollution on adjacent coral reefs at six sites. Multivariate analyses of benthic and coral community data found similar modern reef development at three locations; Aoa, Alofau, and Leone. These sites are situated in isolated bays with gentle sloping foundations. Aoa reefs had the highest estimates of crustose coralline algae cover and coral species richness, while Leone and Alofau showed high abundances of macroalgae and Porites corals. Aoa has the largest reef flat between watershed discharge and the reef slope, and the lowest human population density. Masefau and Fagaalu have a different geomorphology consisting of cemented staghorn coral fragments and steep slopes, however, benthic and coral communities were not similar. Benthic data suggest Fagaalu is heavily impacted compared with all other sites. Reef communities were assessed as bio-criteria indicators for waterbody health, using the EPA aquatic life use support designations of (1) fully supportive, (2) partially supportive, and (3) non-supportive for aquatic life. All sites resulted in a partially supportive ranking except Fagaalu, which was non-supportive. The results of this rapid assessment based upon relative benthic community measures are less desirable than long-term dataset analyses from monitoring programs, however it fills an important role for regulatory agencies required to report annual waterbody assessments. Future monitoring sites should be established to increase the number of replicates within each geological and physical setting to allow for meaningful comparisons along a gradient of hypothesized pollution levels. PMID:16418902

Houk, Peter; Didonato, Guy; Iguel, John; Van Woesik, Robert

2005-08-01

341

A novel reef coral symbiosis  

NASA Astrophysics Data System (ADS)

Reef building corals form close associations with unicellular microalgae, fungi, bacteria and archaea, some of which are symbiotic and which together form the coral holobiont. Associations with multicellular eukaryotes such as polychaete worms, bivalves and sponges are not generally considered to be symbiotic as the host responds to their presence by forming physical barriers with an active growth edge in the exoskeleton isolating the invader and, at a subcellular level, activating innate immune responses such as melanin deposition. This study describes a novel symbiosis between a newly described hydrozoan ( Zanclea margaritae sp. nov.) and the reef building coral Acropora muricata (= A. formosa), with the hydrozoan hydrorhiza ramifying throughout the coral tissues with no evidence of isolation or activation of the immune systems of the host. The hydrorhiza lacks a perisarc, which is typical of symbiotic species of this and related genera, including species that associate with other cnidarians such as octocorals. The symbiosis was observed at all sites investigated from two distant locations on the Great Barrier Reef, Australia, and appears to be host species specific, being found only in A. muricata and in none of 30 other species investigated at these sites. Not all colonies of A. muricata host the hydrozoans and both the prevalence within the coral population (mean = 66%) and density of emergent hydrozoan hydranths on the surface of the coral (mean = 4.3 cm-2, but up to 52 cm-2) vary between sites. The form of the symbiosis in terms of the mutualism-parasitism continuum is not known, although the hydrozoan possesses large stenotele nematocysts, which may be important for defence from predators and protozoan pathogens. This finding expands the known A. muricata holobiont and the association must be taken into account in future when determining the corals’ abilities to defend against predators and withstand stress.

Pantos, O.; Bythell, J. C.

2010-09-01

342

Morphologies of rocks within and near the Rock Garden at the Mars Pathfinder landing site  

Microsoft Academic Search

This paper considers the morphology of several rocks and rock fragments within and near the Rock Garden at the Mars Pathfinder landing site. We have analyzed stereo images taken both by the lander IMP camera and by the rover forward cameras. The rocks were found to differ in their roundness\\/angularity and in their densities of millimeter-to-centimeter-sized pits and flute-like features

A. T. Basilevsky; W. J. Markiewicz; N. Thomas; H. U. Keller

1999-01-01

343

General circulation model simulations of the Mars Pathfinder atmospheric structure investigation\\/meteorology data  

Microsoft Academic Search

The NASA Ames Mars General Circulation Model is used to interpret selected results from the Mars Pathfinder atmospheric structure instrument\\/meteorology (ASI\\/MET) experiment. The present version of the model has an improved soil thermal model, a new boundary layer scheme, and a correction for non-local thermodynamic equilibrium effects at solar wavelengths. We find good agreement with the ASI\\/MET entry data if

Robert M. Haberle; Manoj M. Joshi; James R. Murphy; Jeffrey R. Barnes; John T. Schofield; Greg Wilson; Miguel Lopez-Valverde; Jeffery L. Hollingsworth; Alison F. C. Bridger; James Schaeffer

1999-01-01

344

A new variant of the Pathfinder algorithm to generate large visual science maps in cubic time  

Microsoft Academic Search

Abstract In the last few years, there is an increasing interest to generate visual representations of very large scientific domains. A methodology,based on the combined,use of ISI–JCR category cocitation and social networks,analysis through the use of the Pathfinder algorithm has demonstrated its ability to achieve high quality, schematic visualizations for these kinds of domains. Now, the next step would be

Arnaud Quirin; Oscar Cordón; Jose Santamaría; Benjamín Vargas-quesada; Félix De Moya Anegón

2008-01-01

345

THE JOINT MILLI-ARCSECOND PATHFINDER SURVEY (J-MAPS): MISSION OVERVIEW  

Microsoft Academic Search

We describe the Joint Milli-Arcsecond Pathfinder Survey (J-MAPS). J-MAPS is an all-sky space-based astrometric survey mission with a primary mission objective of measuring stellar positions and motions to better than 1 milliarcsecond (mas) and 1 mas per year, respectively. J-MAPS will completely update the Hipparcos catalog (1 mas @ epoch=1991.25; 16 mas @ epoch=2006) and the twenty year baseline between

Bryan Dorland; Ralph Gaume; Norbert Zacharias; Valeri Makarov; Kenneth Johnston

346

Structural design and analysis of test mass module for DECIGO Pathfinder  

Microsoft Academic Search

Deci-hertz Interferometer Gravitational-Wave Observatory: DECIGO is a project aimed at future detection of deci-hertz gravitational waves in space. DECIGO Pathfinder: DPF is a precursor mission to test the key technologies with one spacecraft. Our work in this article was to examine the strength of the DPF test mass module to ensure that it is sufficiently robust for launch with a

Y. Wakabayashi; Y. Obuchi; N. Okada; Y. Torii; Y. Ejiri; R. Suzuki; A. Ueda; S. Kawamura; A. Araya; M. Ando; S. Sato; A. Sugamoto

2010-01-01

347

Do cleaning organisms reduce the stress response of client reef fish?  

Microsoft Academic Search

BACKGROUND: Marine cleaning interactions in which cleaner fish or shrimps remove parasites from visiting 'client' reef fish are a textbook example of mutualism. However, there is yet no conclusive evidence that cleaning organisms significantly improve the health of their clients. We tested the stress response of wild caught individuals of two client species, Chromis dimidiata and Pseudanthias squamipinnis, that had

Redouan Bshary; Rui F Oliveira; Tânia SF Oliveira; Adelino VM Canário

2007-01-01

348

Activity-dependent competition regulates motor neuron axon pathfinding via PlexinA3.  

PubMed

The role of electrical activity in axon guidance has been extensively studied in vitro. To better understand its role in the intact nervous system, we imaged intracellular Ca(2+) in zebrafish primary motor neurons (PMN) during axon pathfinding in vivo. We found that PMN generate specific patterns of Ca(2+) spikes at different developmental stages. Spikes arose in the distal axon of PMN and were propagated to the cell body. Suppression of Ca(2+) spiking activity in single PMN led to stereotyped errors, but silencing all electrical activity had no effect on axon guidance, indicating that an activity-based competition rule regulates this process. This competition was not mediated by synaptic transmission. Combination of PlexinA3 knockdown with suppression of Ca(2+) activity in single PMN produced a synergistic increase in the incidence of pathfinding errors. However, expression of PlexinA3 transcripts was not regulated by activity. Our results provide an in vivo demonstration of the intersection of spontaneous electrical activity with the PlexinA3 guidance molecule receptor in regulation of axon pathfinding. PMID:23302694

Plazas, Paola V; Nicol, Xavier; Spitzer, Nicholas C

2013-01-09

349

Estimating Discharge from Ares Vallis Using Pathfinder Images and MOLA Topography  

NSDL National Science Digital Library

On July 4th, 1997, Mars Pathfinder landed at the mouth of Ares Vallis, a large channel that drains into the Chryse Planitia basin. While there remains a great deal to debate about the origin of the channels, one of the leading hypotheses at present is the idea that these features are the result of catastrophic flooding. If this is correct, then the plains where Pathfinder landed may be rich in debris eroded out of the Martian highlands across which the Ares Vallis channel passes, providing a golden combinationa relatively safe landing site which still provides access to a wide variety of different rock types. [If you would like to learn more about the many Pathfinder results, explore the April, 1999 and January, 2000 issues of the Journal of Geophysical ResearchPlanets (the green one) in the library.] For the sake of this lab assignment you will hypothesize that the Ares Vallis and associated deposits were indeed produced by catastrophic flooding, and will use the information at your disposal to learn all you can about the putative flooding event.

Grosfils, Eric

350

Overview of the development of the pathfinder ultra-long duration balloon system  

NASA Astrophysics Data System (ADS)

The ultra-long duration balloon (ULDB) Pathfinder Project is developing a small pumpkin balloon system and a new communication package based on the iridium satellites technology to demonstrate a global, 100-day duration capability that is scalable to the full-scale ULDB. A set of trade studies has been conducted to determine the volume, mass and cost of the balloon system to support up to 90 kg payload mass to an altitude of 35 km. The Pathfinder test balloons will provide valuable data in the development of performance models for future ULDB flights. The iridium based communication package will include a power subsystem, a command and data-handling unit, a GPS receiver, and an iridium L-Band Transceiver (LBT) for global communications. The flight data will include, at a minimum: latitude, longitude, altitude, horizontal and vertical speeds, heading, time, and other balloon performance parameters (i.e., system voltages, temperatures, etc.). Although the system will be designed for global launch capability, initial flights will be launched from the proposed full-scale ULDB mission launch locations. This paper will present and discuss the initial series of trade studies conducted for the development of the pathfinder balloon and the design concept of the iridium based communication package.

Said, Magdi A.; Stuchlik, David; Corbin, Brian; Smolinski, Michael; Abresch, Brian; Shreves, Christopher; Stancil, Robert; Cathey, Henry M.; Cannon, Scott

2004-01-01

351

Estimating Discharge from Ares Vallis Using Pathfinder Images and MOLA Topography  

NSDL National Science Digital Library

On July 4th, 1997, Mars Pathfinder landed at the mouth of Ares Vallis, a large channel that drains into the Chryse Planitia basin. While there remains a great deal to debate about the origin of the channels, one of the leading hypotheses at present is the idea that these features are the result of catastrophic flooding. If this is correct, then the plains where Pathfinder landed may be rich in debris eroded out of the Martian highlands across which the Ares Vallis channel passes, providing a golden combinationâa relatively safe landing site which still provides access to a wide variety of different rock types. [If you would like to learn more about the many Pathfinder results, explore the April, 1999 and January, 2000 issues of the journal Journal of Geophysical ResearchâPlanets (the green one) in the library.] For the sake of this lab assignment you will hypothesize that the Ares Vallis and associated deposits were indeed produced by catastrophic flooding, and will use the information at your disposal to learn all you can about the putative flooding event.

Grosfils, Eric

352

pathFinder: A Static Network Analysis Tool for Pharmacological Analysis of Signal Transduction Pathways  

NSDL National Science Digital Library

The study of signal transduction is becoming a de facto part of the analysis of gene expression and protein profiling techniques. Many online tools are used to cluster genes in various ways or to assign gene products to signal transduction pathways. Among these, pathFinder is a unique tool that can find signal transduction pathways between first, second, or nth messengers and their targets within the cell. pathFinder can identify qualitatively all possible signal transduction pathways connecting any starting component and target within a database of two-component pathways (directional dyads). One or more intermediate pathway components can be excluded to simulate the use of pharmacological inhibitors or genetic deletion (knockout). Missing elements in a pathway connecting the activator or initiator and target can also be inferred from a null pathway result. The value of this static network analysis tool is illustrated by the predication from pathFinder analysis of a novel cyclic AMP–dependent, protein kinase A–independent signaling pathway in neuroendocrine cells, which has been experimentally confirmed.

Babru B. Samal (NIH;National Institute of Mental Health--Intramural Research Programs (NIMH-IRP) Bioinformatics Core REV); Lee E. Eiden (NIH;Section on Molecular Neuroscience REV)

2008-08-05

353

Origins and development of Holocene coral reefs: a revisited model based on reef boreholes in the Seychelles, Indian Ocean  

Microsoft Academic Search

Until recently, concepts of coral reef growth and accumulation have been predominantly based on a Darwinian model. In this,\\u000a the upwards and outwards growth of a reef core (a coral framework) takes place over a foreslope consisting of reef talus,\\u000a with the simultaneous filling of the back-reef lagoon by reef-derived debris. The principal adaptations of this pattern relate\\u000a to the

C. J. R. Braithwaite; L. F. Montaggioni; G. F. Camoin; H. Dalmasso; W. C. Dullo; A. Mangini

2000-01-01

354

Climate change and coral reef bleaching: An ecological assessment of long-term impacts, recovery trends and future outlook  

NASA Astrophysics Data System (ADS)

Since the early 1980s, episodes of coral reef bleaching and mortality, due primarily to climate-induced ocean warming, have occurred almost annually in one or more of the world's tropical or subtropical seas. Bleaching is episodic, with the most severe events typically accompanying coupled ocean-atmosphere phenomena, such as the El Niño-Southern Oscillation (ENSO), which result in sustained regional elevations of ocean temperature. Using this extended dataset (25+ years), we review the short- and long-term ecological impacts of coral bleaching on reef ecosystems, and quantitatively synthesize recovery data worldwide. Bleaching episodes have resulted in catastrophic loss of coral cover in some locations, and have changed coral community structure in many others, with a potentially critical influence on the maintenance of biodiversity in the marine tropics. Bleaching has also set the stage for other declines in reef health, such as increases in coral diseases, the breakdown of reef framework by bioeroders, and the loss of critical habitat for associated reef fishes and other biota. Secondary ecological effects, such as the concentration of predators on remnant surviving coral populations, have also accelerated the pace of decline in some areas. Although bleaching severity and recovery have been variable across all spatial scales, some reefs have experienced relatively rapid recovery from severe bleaching impacts. There has been a significant overall recovery of coral cover in the Indian Ocean, where many reefs were devastated by a single large bleaching event in 1998. In contrast, coral cover on western Atlantic reefs has generally continued to decline in response to multiple smaller bleaching events and a diverse set of chronic secondary stressors. No clear trends are apparent in the eastern Pacific, the central-southern-western Pacific or the Arabian Gulf, where some reefs are recovering and others are not. The majority of survivors and new recruits on regenerating and recovering coral reefs have originated from broadcast spawning taxa with a potential for asexual growth, relatively long distance dispersal, successful settlement, rapid growth and a capacity for framework construction. Whether or not affected reefs can continue to function as before will depend on: (1) how much coral cover is lost, and which species are locally extirpated; (2) the ability of remnant and recovering coral communities to adapt or acclimatize to higher temperatures and other climatic factors such as reductions in aragonite saturation state; (3) the changing balance between reef accumulation and bioerosion; and (4) our ability to maintain ecosystem resilience by restoring healthy levels of herbivory, macroalgal cover, and coral recruitment. Bleaching disturbances are likely to become a chronic stress in many reef areas in the coming decades, and coral communities, if they cannot recover quickly enough, are likely to be reduced to their most hardy or adaptable constituents. Some degraded reefs may already be approaching this ecological asymptote, although to date there have not been any global extinctions of individual coral species as a result of bleaching events. Since human populations inhabiting tropical coastal areas derive great value from coral reefs, the degradation of these ecosystems as a result of coral bleaching and its associated impacts is of considerable societal, as well as biological concern. Coral reef conservation strategies now recognize climate change as a principal threat, and are engaged in efforts to allocate conservation activity according to geographic-, taxonomic-, and habitat-specific priorities to maximize coral reef survival. Efforts to forecast and monitor bleaching, involving both remote sensed observations and coupled ocean-atmosphere climate models, are also underway. In addition to these efforts, attempts to minimize and mitigate bleaching impacts on reefs are immediately required. If significant reductions in greenhouse gas emissions can be achieved within the next two to three decades, maximizing coral surv

Baker, Andrew C.; Glynn, Peter W.; Riegl, Bernhard

2008-12-01

355

Coral-reef hydrology: field studies of water movement within a barrier reef  

NASA Astrophysics Data System (ADS)

Water movement through the framework of Davies Reef, a coral reef in the central Australian Great Barrier Reef, was studied using field and laboratory determinations of permeability, tide gauge measurements of water levels, dye tracers, and pore water chemistry. Flow is driven by current, wind-induced, or tide-induced water level differences which were shown to occur between reef front and lagoon. The reef is hydraulically very heterogeneous with bulk flow occurring through high permeability zones (voids and rubble) at a velocity on the order of 10 m/d. Pore water exchange in less permeable zones occurs at a much slower rate. Vertical components of flow are significant. Chemical data indicate that carbonate precipitation and solution occur so that porosities, permeabilities, and flow paths may change with time. Implications for nutrient transfer through the benthic sediments and for fresh water resources on reef islands are discussed.

Oberdorfer, J. A.; Buddemeier, R. W.

1986-08-01

356

Miocene reef carbonates of Mariana Islands  

SciTech Connect

Miocene carbonates in the southern Mariana Islands are impressive for their lithologic diversity, thicknesses (over 250 m), and geographic extent (> 20% combined outcrop coverage over four major high islands: Guam, Rota, Tinian and Saipan). Sections are dominated either by lagoonal algal-foraminiferal wackestones and mudstones with locally abundant high-energy shelly-skeletal facies, or by rubbly to muddy, fore-reef-to-bank deposits of packstones and grainstones with highly diverse and variable biogenic clasts. Fresh to deeply weathered volcaniclastic material may comprise at least 80% of some high-energy fore-reef facies, whereas lagoonal and bank deposits usually contain less than 0.5% terrigenous material. Surprisingly, the Miocene in the Marianas lacks almost completely any reef-core facies. Several poorly developed coral-rich mounds on Saipan and localized laminated red algal buildups on Guam appear to constitute the extant reef-wall facies in the Miocene. The lack of buildups may be a matter of differential survival; it may result from headland erosion and benching associated with emergence of narrow reef tracts as has been postulated by others for south Guam. Alternatively, the authors are proposing that Miocene bathymetry and the volume of terrigenous influx militated against significant reef core formation. Radiometric age dating of these reef carbonates has proven unsuccessful because pervasive diagenesis has transformed the entire Miocene section into low-magnesium calcite with minor and occasional dolomite. Freshwater phreatic diagenesis accounts for the principal porosity variation and trace element distribution.

Siegrist, H.G. Jr.

1988-02-01

357

Uptake of picophytoplankton, bacterioplankton and virioplankton by a fringing coral reef community (Ningaloo Reef, Australia)  

Microsoft Academic Search

We examined the importance of picoplankton and virioplankton to reef trophodynamics at Ningaloo Reef, (north-western Australia),\\u000a in May and November 2008. Picophytoplankton (Prochlorococcus, Synechococcus and picoeukaryotes), bacterioplankton (inclusive of bacteria and Archaea), virioplankton and chlorophyll a (Chl a) were measured at five stations following the consistent wave-driven unidirectional mean flow path of seawater across the\\u000a reef and into the lagoon.

N. L. PattenA; A. S. J. Wyatt; R. J. Lowe; A. M. Waite

2011-01-01

358

Nocturnal relocation of adult and juvenile coral reef fishes in response to reef noise  

Microsoft Academic Search

Juvenile and adult reef fishes often undergo migration, ontogenic habitat shifts, and nocturnal foraging movements. The orientation\\u000a cues used for these behaviours are largely unknown. In this study, the use of sound as an orientation cue guiding the nocturnal\\u000a movements of adult and juvenile reef fishes at Lizard Island, Great Barrier Reef was examined. The first experiment compared\\u000a the movements

S. D. Simpson; A. Jeffs; J. C. Montgomery; R. D. McCauley; M. G. Meekan

2008-01-01

359

Remote sensing of sea surface temperatures during 2002 Barrier Reef coral bleaching  

NASA Astrophysics Data System (ADS)

Early in 2002, satellites of the U.S. National Oceanic and Atmospheric Administration (NOAA) detected anomalously high sea surface temperatures (SST) developing in the western Coral Sea, midway along Australia's Great Barrier Reef (GBR). This was the beginning of what was to become the most significant GBR coral bleaching event on record [Wilkinson, 2002]. During this time, NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) provided satellite data as part of ongoing collaborative work on coral reef health with the Australian Institute of Marine Science (AIMS) and the Great Barrier Reef Marine Park Authority (GBRMPA). These data proved invaluable to AIMS and GBRMPA as they monitored and assessed the development and evolution of SSTs throughout the austral summer, enabling them to keep stakeholders, government, and the general public informed and up to date.

Liu, Gang; Strong, Alan E.; Skirving, William

360

Ocean acidification accelerates reef bioerosion.  

PubMed

In the recent discussion how biotic systems may react to ocean acidification caused by the rapid rise in carbon dioxide partial pressure (pCO(2)) in the marine realm, substantial research is devoted to calcifiers such as stony corals. The antagonistic process - biologically induced carbonate dissolution via bioerosion - has largely been neglected. Unlike skeletal growth, we expect bioerosion by chemical means to be facilitated in a high-CO(2) world. This study focuses on one of the most detrimental bioeroders, the sponge Cliona orientalis, which attacks and kills live corals on Australia's Great Barrier Reef. Experimental exposure to lowered and elevated levels of pCO(2) confirms a significant enforcement of the sponges' bioerosion capacity with increasing pCO(2) under more acidic conditions. Considering the substantial contribution of sponges to carbonate bioerosion, this finding implies that tropical reef ecosystems are facing the combined effects of weakened coral calcification and accelerated bioerosion, resulting in critical pressure on the dynamic balance between biogenic carbonate build-up and degradation. PMID:23028797

Wisshak, Max; Schönberg, Christine H L; Form, Armin; Freiwald, André

2012-09-18

361

Coral Reef Adventure Fun Zone  

NSDL National Science Digital Library

The Memory Game beginner is the best game for students of all ages to play unless there is a student who knows an unusual amount of information about coral reefs. In this case, that student can play the expert level where he/she will match the name or phrase with a picture.To begin, students should click on the GO! icon on the Memory Game and then again on the GO! icon on the pop-up screen. The beginner version requires students to match alike pictures. Students should click on the images to find the matching pairs. As they click on an image and then click on another, the previous image goes away if it's not a match.so students need to remember where they clicked on each image.Once students find a matching pair, they need to click on one image and then click on its matching image to keep the matching pair on the screen. Students should continue this process until all the images are found. On the bottom left of this screen there is a Move counter that keeps track of how many times students click on an image. If students want to try again to achieve a better score, then they can start the game over on a new screen. As noted below, there are other games that would be suitable for playing after students learn more about coral reefs.

Science NetLinks (AAAS;)

2007-04-29

362

Ocean Acidification Accelerates Reef Bioerosion  

PubMed Central

In the recent discussion how biotic systems may react to ocean acidification caused by the rapid rise in carbon dioxide partial pressure (pCO2) in the marine realm, substantial research is devoted to calcifiers such as stony corals. The antagonistic process – biologically induced carbonate dissolution via bioerosion – has largely been neglected. Unlike skeletal growth, we expect bioerosion by chemical means to be facilitated in a high-CO2 world. This study focuses on one of the most detrimental bioeroders, the sponge Cliona orientalis, which attacks and kills live corals on Australia’s Great Barrier Reef. Experimental exposure to lowered and elevated levels of pCO2 confirms a significant enforcement of the sponges’ bioerosion capacity with increasing pCO2 under more acidic conditions. Considering the substantial contribution of sponges to carbonate bioerosion, this finding implies that tropical reef ecosystems are facing the combined effects of weakened coral calcification and accelerated bioerosion, resulting in critical pressure on the dynamic balance between biogenic carbonate build-up and degradation.

Wisshak, Max; Schonberg, Christine H. L.; Form, Armin; Freiwald, Andre

2012-01-01

363

Numerical modeling of atoll reef harbors  

SciTech Connect

The effect of the shape of a harbor cut through a reef on mitigating waves from the deep ocean was studied using a shallow water, nonlinear, long wave code called SWAN. A significant amount of the wave energy is dissipated over the reef regardless of the design of the harbor. The reef resulted in decreasing the wave height by a factor 3. The wave height at the shore can be further decreased by another factor of 2 by a ''V'' shaped or parabolic bottom design.

Mader, C.L.; Vitousek, M.; Lukas, S.

1986-01-01

364

Geomorphology of unique reefs on the western Canadian shelf: sponge reefs mapped by multibeam bathymetry  

NASA Astrophysics Data System (ADS)

Multibeam imagery of siliceous sponge reefs (Hexactinellida, Hexactinosida) reveals the setting, form, and organization of five reef complexes on the western Canadian continental shelf. The reefs are built by framework skeleton sponges which trap clay-rich sediments resulting in a distinctive pattern of low intensity backscatter from the reefs that colonize more reflective glacial sediments of higher backscatter intensity. Bathymetry and backscatter maps show the distribution and form of reefs in two large complexes in the Queen Charlotte Basin (QCB) covering hundreds of km2, and three smaller reef complexes in the Georgia Basin (GB). Ridges up to 7 km long and 21 m in height, together with diversely shaped, coalescing bioherms and biostromes form the principal reef shape in the QCB whereas chains of wave-form, streamlined mounds up to 14 m in height have developed in the GB. Reef initiation is dependent on the distribution of high backscatter-intensity relict glacial surfaces, and the variation in reef complex morphology is probably the result of tidally driven, near seabed currents.

Conway, Kim W.; Barrie, J. Vaughn; Krautter, Manfred

2005-09-01

365

Reef fish and habitat relationships in a Caribbean seascape: the importance of reef context  

NASA Astrophysics Data System (ADS)

Marine protected area (MPA) effectiveness is contingent on understanding key ecological patterns and processes at appropriate spatial scales and may depend upon maintaining critical linkages among essential habitat patches to conserve reef-fish communities. Hypotheses were tested to investigate the importance of habitat linkages in the US Virgin Islands. As expected, reef context (the spatial pattern of surrounding habitat patches) was a strong predictor of reef fish assemblage structure. Specific relationships were functionally consistent with the ecology of the fishes of interest. For example, reefs with large amounts of seagrass nearby harbored the greatest numerical abundance of fishes, particularly mobile invertebrate feeders and the exploited fish families of Haemulidae (grunts) and Lutjanidae (snappers). Species richness for the entire fish community and within these fish groups was also strongly associated with reef context. Furthermore, reef fish mobility influenced how fishes related to reef context. Fish-habitat relationships were detected as far as 1 km from study reefs, suggesting that fish movements result in habitat encounter rates that may influence their patterns of distribution. Consequently, functional habitat connectivity of habitat patches appears important in structuring reef-fish assemblages, and suggests that landscape-scale metrics may provide insights useful to managers in the design of MPAs.

Grober-Dunsmore, R.; Frazer, T. K.; Lindberg, W. J.; Beets, J.

2007-03-01

366

Florida's Fragile Reefs: What's Happening to this Underwater World?  

NSDL National Science Digital Library

This BioBulletin Web site takes an in-depth look at coral reefs and how they are affected by human activities: everything from agricultural pollution and ship grounding to snorkeling and overfishing. With Florida's fragile reefs as the backdrop, the site includes text, videos and photographs. The Introduction explains the fragility of these the massive underwater structures. What Are Reefs? discusses how these "rain forests of the sea" support an even more astonishing variety of life. Reefs in Hot Water presents the factors behind why reefs around the world are declining at an unprecedented rate. Monitoring a Reef at Risk covers the Florida Keys Coral Reef Monitoring Project, funded by the Environmental Protection Agency. Treating Reefs Right lists ways in which boaters, fishermen, swimmers, and divers can do their part to protect coral reefs.

367

Coral reefs of the Mascarenes, Western Indian Ocean.  

PubMed

The reefs of the Mascarenes differ in structure and stage of development. Mauritius is the oldest island, bound by a discontinuous fringing reef and small barrier reef, with large lagoon patch reefs. Rodrigues has nearly continuous fringing reefs bounding an extensive lagoon with deep channels and few patch reefs. Reunion, the youngest island, has short stretches of narrow fringing reefs along southwestern coasts. The islets of St Brandon are bound to the east by an extensive arc of fringing reef. Reef mapping of the Mascarenes using satellite imagery provides an estimate of 705 km2 of shallow reef habitats. These areas have been modified over geological time by changes in sea level, ocean-atmosphere disturbances and biological and chemical forcing. Further modification has resulted from historical changes in land-use patterns. Recent economic development has placed many of these reefs at risk from anthropogenic impact. The reefs of the Mascarenes have escaped mass mortality from bleaching to date, which increases their conservation significance within the wider Indian Ocean. The reefs are poorly protected. A case study shows how a geographic information system incorporating reef-habitat maps can help formulate and demonstrate Marine Protected Area boundaries. PMID:15598634

Turner, John; Klaus, Rebecca

2005-01-15

368

Reef Ecosystem Services and Decision Support Database  

EPA Science Inventory

This scientific and management information database utilizes systems thinking to describe the linkages between decisions, human activities, and provisioning of reef ecosystem goods and services. This database provides: (1) Hierarchy of related topics - Click on topics to navigat...

369

Climate Change: Effects on Reef Island Resources.  

National Technical Information Service (NTIS)

The salinity, depth, quantity, and reliability of fresh groundwater resources on coral reef islands and coastlines are environmentally important parameters. Groundwater influences or controls the terrestrial flora, salinity, and nutrient levels in the nea...

J. A. Oberdorfer R. W. Buddemeier

1988-01-01

370

Extinction vulnerability of coral reef fishes  

PubMed Central

With rapidly increasing rates of contemporary extinction, predicting extinction vulnerability and identifying how multiple stressors drive non-random species loss have become key challenges in ecology. These assessments are crucial for avoiding the loss of key functional groups that sustain ecosystem processes and services. We developed a novel predictive framework of species extinction vulnerability and applied it to coral reef fishes. Although relatively few coral reef fishes are at risk of global extinction from climate disturbances, a negative convex relationship between fish species locally vulnerable to climate change vs. fisheries exploitation indicates that the entire community is vulnerable on the many reefs where both stressors co-occur. Fishes involved in maintaining key ecosystem functions are more at risk from fishing than climate disturbances. This finding is encouraging as local and regional commitment to fisheries management action can maintain reef ecosystem functions pending progress towards the more complex global problem of stabilizing the climate.

Graham, Nicholas A J; Chabanet, Pascale; Evans, Richard D; Jennings, Simon; Letourneur, Yves; Aaron MacNeil, M; McClanahan, Tim R; Ohman, Marcus C; Polunin, Nicholas V C; Wilson, Shaun K

2011-01-01

371

Oysters and Oyster Reef Communities in Florida.  

ERIC Educational Resources Information Center

The habitat, life history, feeding, classification, anatomy and pearl production of the American oyster (Crassostrea virginica) are presented. A list of other oyster reef inhabitants and predators is provided. Harvest and habitat loss are discussed. (CW)

Knight, Jean; Bly, Joe

1989-01-01

372

Paleobiologic and paleoenvironmental context of coral-bearing Early Cambrian reefs: Implications for Phanerozoic reef development  

NASA Astrophysics Data System (ADS)

Early Cambrian corals from South Australia have been found within fossil reefs of unusual biological and paleoecological composition. The framework of these reefs is composed of a diverse assemblage of calcareous sponges (e.g., archaeocyaths and sphinctozoans), calci-microbes, and at least two species of coral-like organisms, one of which is first reported herein and bears similarities to younger Paleozoic tabulate corals. Complex growth interactions occur among these organisms, suggesting that space was a limiting factor in Early Cambrian reef ecosystems, as it is today in modern scleractinian reefs. In striking contrast to most Early Cambrian archaeocyath-calcimicrobe reefs, these South Australian reefs flourished within energetic, mixed silici-clastic-carbonate shallow-marine environments along the margins of arid, coarse-grained, sea-marginal alluvial fans. The implications of these coral-bearing reefs are multifold. First, their existence not only extends the range of tabulatelike corals to the Botomian (middle Early Cambrian), but it adds an additional clade of participants to the Early Cambrian metazoan radiation event. Second, the existence of Botomian-aged skeletonized colonial cnidarians necessitates an earliest Cambrian or Neoproterozoic ancestor for the group. Third, the presence of tabulatelike corals and their involvement in reef building prior to the Toyonian extinction (late Early Cambrian) challenges hypotheses (e.g., lack of a suitable reef builder after the extinction of archaeocyaths until the Ordovician) used to explain the paucity of Middle and Late Cambrian reefs worldwide. The presence of these corals on sea-marginal fans contradicts the perception that early reefs were restricted to low-energy, predominantly carbonate subtidal environments.

Savarese, Michael; Mount, Jeffrey F.; E., James; Bucklin, Louis

1993-10-01

373

Remote Sensing of Coral Reef Processes  

Microsoft Academic Search

\\u000a Digital remote sensing of coral reefs dates to the first Landsat mission of the mid-1970s. Early studies utilized moderate-spatial-resolution\\u000a satellite broadband multispectral image data and focused on reef geomorphology. Technological advances have since led to development\\u000a of airborne narrow-band hyperspectral sensors, airborne hydrographic lidar systems, and commercial high-spatial-resolution\\u000a satellite broadband multispectral imagers. High quality remote sensing data have become widely

Eric J. Hochberg

374

Mass Spawning in Tropical Reef Corals  

NASA Astrophysics Data System (ADS)

Synchronous multispecific spawning by a total of 32 coral species occurred a few nights after late spring full moons in 1981 and 1982 at three locations on the Great Barrier Reef, Australia. The data invalidate the generalization that most corals have internally fertilized, brooded planula larvae. In every species observed, gametes were released; external fertilization and development then followed. The developmental rates of externally fertilized eggs and longevities of planulae indicate that planulae may be dispersed between reefs.

Harrison, Peter L.; Babcock, Russell C.; Bull, Gordon D.; Oliver, James K.; Wallace, Carden C.; Willis, Bette L.

1984-03-01

375

Relationships between coral reef substrata and fish  

Microsoft Academic Search

.  ?The objective of this work is to identify which substrata characteristics (such as coral morphology, coral diversity, coral\\u000a species richness, percentage coverage by live coral or by algae) influence the structure and abundance of fish communities.\\u000a The study was carried out at Reunion Island, Indian Ocean, where six sites were sampled in two zones (reef flat and outer\\u000a reef slope).

P. Chabanet; H. Ralambondrainy; M. Amanieu; G. Faure; R. Galzin

1997-01-01

376

Shallow pore water sampling in reef sediments  

Microsoft Academic Search

Several new techniques have been developed to allow the geochemical characterization of shallow pore waters in reefs. First,\\u000a a new method was developed for using non-metallic well-points to sample pore waters from shallow depths (<1?m) in coral reefs\\u000a with unconsolidated substrates. These PVC well-points can be made faster and at less expense than well-points made of stainless\\u000a steel. They also

J. L. Falter; F. J. Sansone

2000-01-01

377

Macroalgal blooms on southeast Florida coral reefs  

Microsoft Academic Search

Abstract Invasive bloomsof the siphonaceous greenalgae Codiumspp. have been considered a symptom ofcoastal eutrophicationbut, to date, only limitedbiochemical evidence supports a linkage to land-based nutrient pollution. Beginningin the summer of 1990, spectacular blooms,of unattached Codium isthmocladum,developed on deep coral reef habitats in southern Palm Beach County and northern Broward County, and in subsequent years, attached populations formed on reefs in

Brian E. Lapointe; Peter J. Barile; Mark M. Littler; Diane S. Littler; Bradley J. Bedford; Constance Gasque

378

Development of a field test environment for the validation of coastal remote sensing algorithms: Enrique Reef, Puerto Rico  

NASA Astrophysics Data System (ADS)

Remote sensing is increasingly being used as a tool to quantitatively assess the location, distribution and relative health of coral reefs and other shallow aquatic ecosystems. As the use of this technology continues to grow and the analysis products become more sophisticated, there is an increasing need for comprehensive ground truth data as a means to assess the algorithms being developed. The University of Puerto Rico at Mayaguez (UPRM), one of the core partners in the NSF sponsored Center for Subsurface Sensing and Imaging Systems (CenSSIS), is addressing this need through the development of a fully-characterized field test environment on Enrique Reef in southwestern Puerto Rico. This reef area contains a mixture of benthic habitats, including areas of seagrass, sand, algae and coral, and a range of water depths, from a shallow reef flat to a steeply sloping forereef. The objective behind the test environment is to collect multiple levels of image, field and laboratory data with which to validate physical models, inversion algorithms, feature extraction tools and classification methods for subsurface aquatic sensing. Data collected from Enrique Reef currently includes airborne, satellite and field-level hyperspectral and multispectral images, in situ spectral signatures, water bio-optical properties and information on habitat composition and benthic cover. We present a summary of the latest results from Enrique Reef, discuss our concept of an open testbed for the remote sensing community and solicit other users to utilize the data and participate in ongoing system development.

Goodman, James A.; Vélez-Reyes, Miguel; Hunt, Shawn; Armstrong, Roy

2006-10-01

379

Miocene reef carbonates of Mariana Islands  

SciTech Connect

Miocene carbonates in the southern Mariana Islands are impressive for their lithologic diversity, thicknesses (over 250 m), and geographic extend (>20% combined outcrop coverage over four major high islands: Guam, Rota, Tinian and Saipan). Sections are dominated either by lagoonal algal-foraminiferal wackestones and mudstones with locally abundant high-energy shelly-skeletal facies, or by rubbly to muddy, fore-reef-to-bank deposits of packstones and grainstones with highly diverse and variable biogenic clasts. Fresh to deeply weathered volcaniclastic material may comprise at least 80% of some high-energy fore-reef facies, whereas lagoonal and bank deposits usually contain less than 0.5% terrigenous material. Surprisingly, the Miocene in the Marianas lacks almost completely any reef-core facies. Several poorly developed coral-rich mounds on Saipan and localized laminated red algal buildups on Guam appear to constitute the extant reef-wall facies in the Miocene. The lack of buildups may be a matter of differential survival; it may result from headland erosion and benching associated with emergency of narrow reef tracts as has been postulated by others for south Guam. Radiometric age dating of these reef carbonates has proven unsuccessful because pervasive diagenesis has transformed the entire Miocene section into low-magnesium calcite with minor and occasional dolomite. Freshwater phreatic diagenesis accounts for the principal porosity variation and trace element distribution.

Siegrist, H.G. Jr.

1988-01-01

380

Coral reefs and the World Bank.  

PubMed

The World Bank¿s involvement in coral reef conservation is part of a larger effort to promote the sound management of coastal and marine resources. This involves three major thrusts: partnerships, investments, networks and knowledge. As an initial partner and early supporter of the International Coral Reef Initiative (ICRI), the Bank serves as the executive planning committee of ICRI. In partnership with the World Conservation Union and the Great Barrier Reef Marine Park Authority, the Bank promotes the efforts towards the establishment and maintenance of a globally representative system of marine protected areas. In addition, the Bank invested over $120 million in coral reef rehabilitation and protection programs in several countries. Furthermore, the Bank developed a ¿Knowledge Bank¿ that would market ideas and knowledge to its clients along with investment projects. This aimed to put the best global knowledge on environmentally sustainable development in the hands of its staff and clients. During the celebration of 1997, as the International Year of the Reef, the Bank planned to cosponsor an associated event that would highlight the significance of coral reefs and encourage immediate action to halt their degradation to conserve this unique ecosystem. PMID:12295815

Hatziolos, M

1997-01-01

381

Philippine Coral Reefs Under Threat: The Economic Losses Caused by Reef Destruction  

Microsoft Academic Search

In the Philippines, coral reef fisheries provide livelihood for more than a million small-scale fishers who contribute almost US$ 1 billion annually to the country’s economy. The rapidly growing population needs increasing amounts of fish and other marine organisms. However, overfishing, destructive fishing methods and sedimentation have damaged or destroyed many reef areas. Fish catches have fallen well below the

Alan T White; Helge P Vogt; Tijen Arin

2000-01-01

382

Grazing pressure of herbivorous coral reef fishes on low coral-cover reefs  

NASA Astrophysics Data System (ADS)

The impact of grazing by herbivorous fishes (Acanthuridae, Scaridae, and Pomacentridae) on low coral-cover reefs was assessed by measuring rates of benthic algal production and consumption on inshore and offshore reefs in the upper Florida Keys. Algal production rates, determined in situ with caged and uncaged experimental plates, were low (mean 1.05gCm-2 day-1) and similar among reef types. Algal consumption rates were estimated using two different models, a detailed model incorporating fish bite rates and algal yield-per-bite for one species extrapolated to a guild-wide value, and a general regression relating fish biomass to algal consumption. Algal consumption differed among reef types: a majority of algal production was consumed on offshore reefs (55-100%), whereas consumption on inshore patch reefs was 31-51%. Spatial variation in algal consumption was driven by differences in herbivorous fish species composition, density, and size-structure among reef types. Algal consumption rates also varied temporally due to seasonal declines in bite rates and intermittent presence of large-bodied, vagile, schooling species. Spatial coherence of benthic community structure and temporal stability of algal turf over 3 years suggests that grazing intensity is currently sufficient to limit further spread of macroalgal cover on these low coral-cover reefs, but not to exclude it from the system.

Paddack, Michelle J.; Cowen, Robert K.; Sponaugle, Su

2006-08-01

383

Reef corals of Johnston Atoll: one of the world's most isolated reefs  

Microsoft Academic Search

Johnston Atoll lies 800 km southwest of the nearest reefs of Hawaii and over 1,500 km from other shallow reefs to the south and west. Only 33 species and 16 genera and subgenera of shallow water stony corals have been reported from the atoll. Endemic species are absent despite Johnston's great age and favorable environment. With few exceptions, only species

James E. Maragos; Paul L. Jokiel

1986-01-01

384

U.S. CORAL REEF TASK FORCE CORAL REEFS AND CLIMATE INITIATIVE (NOAA, DOI)  

EPA Science Inventory

In October 2002, the U.S. Coral Reef Task Force passed two resolutions highlighting the impacts of climate change and coral bleaching on coral reefs and calling for an interagency, public/private partnership to advance understanding and management of this issue. In response, the ...

385

Coal Waste Artificial Reef Program: Reef Measurements Over Four Years in the Sea.  

National Technical Information Service (NTIS)

In September 1980, a fishing reef was constructed off the shore of Long Island, southeast of the Fire Island Inlet. The reef consisted of 15,000 blocks made from coal waste materials. The report documents the conclusions of a four-year project that monito...

P. M. J. Woodhead

1987-01-01

386

Soundscapes from a Tropical Eastern Pacific reef and a Caribbean Sea reef  

NASA Astrophysics Data System (ADS)

Underwater soundscapes vary due to the abiotic and biological components of the habitat. We quantitatively characterized the acoustic environments of two coral reef habitats, one in the Tropical Eastern Pacific (Panama) and one in the Caribbean (Florida Keys), over 2-day recording durations in July 2011. We examined the frequency distribution, temporal variability, and biological patterns of sound production and found clear differences. The Pacific reef exhibited clear biological patterns and high temporal variability, such as the onset of snapping shrimp noise at night, as well as a 400-Hz daytime band likely produced by damselfish. In contrast, the Caribbean reef had high sound levels in the lowest frequencies, but lacked clear temporal patterns. We suggest that acoustic measures are an important element to include in reef monitoring programs, as the acoustic environment plays an important role in the ecology of reef organisms at multiple life-history stages.

Staaterman, E.; Rice, A. N.; Mann, D. A.; Paris, C. B.

2013-06-01

387

Variation in depth of whitetip reef sharks: does provisioning ecotourism change their behaviour?  

NASA Astrophysics Data System (ADS)

In the dive tourism industry, shark provisioning has become increasingly popular in many places around the world. It is therefore important to determine the impacts that provisioning may have on shark behaviour. In this study, eight adult whitetip reef sharks Triaenodon obesus were tagged with time-depth recorders at Osprey Reef in the Coral Sea, Australia. Tags collected time and depth data every 30 s. The absolute change in depth over 5-min blocks was considered as a proxy for vertical activity level. Daily variations in vertical activity levels were analysed to determine the effects of time of day on whitetip reef shark behaviour. This was done for days when dive boats were absent from the area, and for days when dive boats were present, conducting shark provisioning. Vertical activity levels varied between day and night, and with the presence of boats. In natural conditions (no boats present), sharks remained at more constant depths during the day, while at night animals continuously moved up and down the water column, showing that whitetip reef sharks are nocturnally active. When boats were present, however, there were also long periods of vertical activity during the day. If resting periods during the day are important for energy budgets, then shark provisioning may affect their health. So, if this behaviour alteration occurs frequently, e.g., daily, this has the potential to have significant negative effects on the animals' metabolic rates, net energy gain and overall health, reproduction and fitness.

Fitzpatrick, Richard; Abrantes, Kátya G.; Seymour, Jamie; Barnett, Adam

2011-09-01

388

The Structure of Mediterranean Rocky Reef Ecosystems across Environmental and Human Gradients, and Conservation Implications  

PubMed Central

Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m?2). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas.

Sala, Enric; Ballesteros, Enric; Dendrinos, Panagiotis; Di Franco, Antonio; Ferretti, Francesco; Foley, David; Fraschetti, Simonetta; Friedlander, Alan; Garrabou, Joaquim; Guclusoy, Harun; Guidetti, Paolo; Halpern, Benjamin S.; Hereu, Bernat; Karamanlidis, Alexandros A.; Kizilkaya, Zafer; Macpherson, Enrique; Mangialajo, Luisa; Mariani, Simone; Micheli, Fiorenza; Pais, Antonio; Riser, Kristin; Rosenberg, Andrew A.; Sales, Marta; Selkoe, Kimberly A.; Starr, Rick; Tomas, Fiona; Zabala, Mikel

2012-01-01

389

Reef Odor: A Wake Up Call for Navigation in Reef Fish Larvae  

PubMed Central

The behavior of reef fish larvae, equipped with a complex toolbox of sensory apparatus, has become a central issue in understanding their transport in the ocean. In this study pelagic reef fish larvae were monitored using an unmanned open-ocean tracking device, the drifting in-situ chamber (DISC), deployed sequentially in oceanic waters and in reef-born odor plumes propagating offshore with the ebb flow. A total of 83 larvae of two taxonomic groups of the families Pomacentridae and Apogonidae were observed in the two water masses around One Tree Island, southern Great Barrier Reef. The study provides the first in-situ evidence that pelagic reef fish larvae discriminate reef odor and respond by changing their swimming speed and direction. It concludes that reef fish larvae smell the presence of coral reefs from several kilometers offshore and this odor is a primary component of their navigational system and activates other directional sensory cues. The two families expressed differences in their response that could be adapted to maintain a position close to the reef. In particular, damselfish larvae embedded in the odor plume detected the location of the reef crest and swam westward and parallel to shore on both sides of the island. This study underlines the critical importance of in situ Lagrangian observations to provide unique information on larval fish behavioral decisions. From an ecological perspective the central role of olfactory signals in marine population connectivity raises concerns about the effects of pollution and acidification of oceans, which can alter chemical cues and olfactory responses.

Paris, Claire B.; Kingsford, Michael; Gerlach, Gabriele; Guigand, Cedric M.

2013-01-01

390

Zebrafish foxP2 zinc finger nuclease mutant has normal axon pathfinding.  

PubMed

foxP2, a forkhead-domain transcription factor, is critical for speech and language development in humans, but its role in the establishment of CNS connectivity is unclear. While in vitro studies have identified axon guidance molecules as targets of foxP2 regulation, and cell culture assays suggest a role for foxP2 in neurite outgrowth, in vivo studies have been lacking regarding a role for foxP2 in axon pathfinding. We used a modified zinc finger nuclease methodology to generate mutations in the zebrafish foxP2 gene. Using PCR-based high resolution melt curve analysis (HRMA) of G0 founder animals, we screened and identified three mutants carrying nonsense mutations in the 2(nd) coding exon: a 17 base-pair (bp) deletion, an 8bp deletion, and a 4bp insertion. Sequence analysis of cDNA confirmed that these were frameshift mutations with predicted early protein truncations. Homozygous mutant fish were viable and fertile, with unchanged body morphology, and no apparent differences in CNS apoptosis, proliferation, or patterning at embryonic stages. There was a reduction in expression of the known foxP2 target gene cntnap2 that was rescued by injection of wild-type foxP2 transcript. When we examined axon pathfinding using a pan-axonal marker or transgenic lines, including a foxP2-neuron-specific enhancer, we did not observe any axon guidance errors. Our findings suggest that foxP2 is not necessary for axon pathfinding during development. PMID:22937139

Xing, Lingyan; Hoshijima, Kazuyuki; Grunwald, David J; Fujimoto, Esther; Quist, Tyler S; Sneddon, Jacob; Chien, Chi-Bin; Stevenson, Tamara J; Bonkowsky, Joshua L

2012-08-24

391

Type III neuregulin 1 regulates pathfinding of sensory axons in the developing spinal cord and periphery  

PubMed Central

Sensory axons must develop appropriate connections with both central and peripheral targets. Whereas the peripheral cues have provided a classic model for neuron survival and guidance, less is known about the central cues or the coordination of central and peripheral connectivity. Here we find that type III Nrg1, in addition to its known effect on neuron survival, regulates axon pathfinding. In type III Nrg1–/– mice, death of TrkA+ nociceptive/thermoreceptive neurons was increased, and could be rescued by Bax elimination. In the Bax and type III Nrg1 double mutants, axon pathfinding abnormalities were seen for TrkA+ neurons both in cutaneous peripheral targets and in spinal cord central targets. Axon guidance phenotypes in the spinal cord included penetration of axons into ventral regions from which they would normally be repelled by Sema3A. Accordingly, sensory neurons from type III Nrg1–/– mice were unresponsive to the repellent effects of Sema3A in vitro, which might account, at least in part, for the central projection phenotype, and demonstrates an effect of type III Nrg1 on guidance cue responsiveness in neurons. Moreover, stimulation of type III Nrg1 back-signaling in cultured sensory neurons was found to regulate axonal levels of the Sema3A receptor neuropilin 1. These results reveal a molecular mechanism whereby type III Nrg1 signaling can regulate the responsiveness of neurons to a guidance cue, and show that type III Nrg1 is required for normal sensory neuron survival and axon pathfinding in both central and peripheral targets.

Hancock, Melissa L.; Nowakowski, Dan W.; Role, Lorna W.; Talmage, David A.; Flanagan, John G.

2011-01-01

392

The end-to-end testbed of the optical metrology system on-board LISA Pathfinder  

NASA Astrophysics Data System (ADS)

LISA Pathfinder is a technology demonstration mission for the Laser Interferometer Space Antenna (LISA). The main experiment on-board LISA Pathfinder is the so-called LISA Technology Package (LTP) which has the aim to measure the differential acceleration between two free-falling test masses with an accuracy of 3 × 10-14 ms-2 Hz-1/2 between 1 mHz and 30 mHz. This measurement is performed interferometrically by the optical metrology system (OMS) on-board LISA Pathfinder. In this paper, we present the development of an experimental end-to-end testbed of the entire OMS. It includes the interferometer and its sub-units, the interferometer backend which is a phasemeter and the processing of the phasemeter output data. Furthermore, three-axes piezo-actuated mirrors are used instead of the free-falling test masses for the characterization of the dynamic behaviour of the system and some parts of the drag-free and attitude control system (DFACS) which controls the test masses and the satellite. The end-to-end testbed includes all parts of the LTP that can reasonably be tested on earth without free-falling test masses. At its present status it consists mainly of breadboard components. Some of those have already been replaced by engineering models of the LTP experiment. In the next steps, further engineering and flight models will also be inserted in this testbed and tested against well-characterized breadboard components. The presented testbed is an important reference for the unit tests and can also be used for validation of the on-board experiment during the mission.

Steier, F.; Guzmán Cervantes, F.; García Marín, A. F.; Gerardi, D.; Heinzel, G.; Danzmann, K.

2009-05-01

393

A phased approach to commissioning MCAO: Status and plans for the Linc-Nirvana Pathfinder  

NASA Astrophysics Data System (ADS)

Layer-oriented multi-conjugate adaptive optics (MCAO) systems apply two or more wavefront-sensor/deformable-mirror (WFS/DM) pairs, each conjugate to a different turbulent layer in the atmosphere. Because these pairs apply correction in series, they are largely decoupled from one another, lending them to a phased commissioning approach. Commissioning instruments on large telescopes, while almost always successful in the end, can be, experience has shown, inefficient and difficult to schedule. For Linc-Nirvana we plan to take advantage of the natural decoupling between the ground-layer subsystem (a 12-star pyramid WFS operating in conjunction with the LBT adaptive secondary) and the mid-high subsystem (an 8-star pyramid WFS working in conjunction with a Xynetics 349 actuator DM) to mitigate the difficulties that have been experienced commissioning complex instruments on large, over-subscribed, telescopes. Pathfinder is a test-bed, consisting of only those subsystems needed to operate, stand-alone, one of the two Linc-Nirvana ground-layer subsystems. The Pathfinder effort will tease out top-level interface issues; while at the same time providing a valuable characterization of the Mount Graham ground-layer. To what extent will this ground-layer system provide a seeing-corrected image to the next WFS/DM pair in the Linc-Nirvana system: the mid-high wavefront-sensor (MHWS)? We will present status and plans for the Linc-Nirvana Pathfinder effort, a novel approach for commissioning MCAO systems on large telescopes.

Conrad, Al; Bertram, Thomas; Kürster, Martin; Herbst, Tom; Ragazzoni, Roberto; Farinato, Jacopo; Viotto, Valentina; Bergomi, Maria; Brunelli, Alessandro; Arcidiacono, Carmelo; Bizenberger, Peter; Briegel, Florian; Hofferbert, Ralph; Gässler, Wolfgang; Meschke, Daniel; Mohr, Lars; Baumeister, Harald; Zhang, Xianyu; Trowitzsch, Jan; Berwein, Jürgen; Kittmann, Frank; Pott, Jorg-Uwe; Rohloff, Ralf-Rainer; Bonis, De Fulvio

2011-09-01

394

The readout system and the trigger algorithm implementation for the UFFO Pathfinder  

NASA Astrophysics Data System (ADS)

Since the launch of the SWIFT, Gamma-Ray Bursts (GRBs) science has been much progressed. Especially supporting many measurements of GRB events and sharing them with other telescopes by the Gamma-ray Coordinate Network (GCN) have resulted the richness of GRB events, however, only a few of GRB events have been measured within a minute after the gamma ray signal. This lack of sub-minute data limits the study for the characteristics of the UV-optical light curve of the short-hard type GRB and the fast-rising GRB. Therefore, we have developed the telescope named the Ultra-Fast Flash Observatory (UFFO) Pathfinder, to take the sub-minute data for the early photons from GRB. The UFFO Pathfinder has a coded-mask X-ray camera to search the GRB location by the UBAT trigger algorithm. To determine the direction of GRB as soon as possible it requires the fast processing. We have ultimately implemented all algorithms in field programmable gate arrays (FPGA) without microprocessor. Although FPGA, when compared with microprocessor, is generally estimated to support the fast processing rather than the complex processing, we have developed the implementation to overcome the disadvantage and to maximize the advantage. That is to measure the location as accurate as possible and to determine the location within the sub-second timescale. In the particular case for a accuracy of the X-ray trigger, it requires special information from the satellite based on the UFFO central control system. We present the implementation of the UBAT trigger algorithm as well as the readout system of the UFFO Pathfinder.

Na, G. W.; Ahmad, S.; Barrillon, P.; Brandt, S.; Budtz-Jørgensen, C.; Castro-Tirado, A. J.; Chen, P.; Choi, Y. J.; Connell, P.; Dagoret-Campagne, S.; Eyles, C.; Grossan, B.; Huang, M.-H. A.; Jeong, S.; Jung, A.; Kim, J. E.; Kim, M. B.; Kim, S.-W.; Kim, Y. W.; Krasnov, Aleksey S.; Lee, J.; Lim, H.; Linder, E. V.; Liu, T.-C.; Lund, N.; Min, K. W.; Nam, J. W.; Park, I. H.; Panasyuk, M. I.; Ripa, J.; Reglero, V.; Rodrigo, J. M.; Smoot, G. F.; Suh, J. E.; Svertilov, S.; Vedenkin, N.; Wang, M.-Z.; Yashin, I.

2012-09-01

395

Coral reef formation theory may apply to oil, gas exploration  

SciTech Connect

This paper reports a coral reef formation theory that has implications for hydrocarbon exploration. The theory states that many coral reefs and carbonate buildups from at and are dependent upon nutrient rich fluids seeping through the seabed.

Not Available

1990-12-10

396

Geologic Measurements using Rover Images: Lessons from Pathfinder with Application to Mars 2001  

NASA Astrophysics Data System (ADS)

The Pathfinder Sojourner rover successfully acquired images that provided important and exciting information on the geology of Mars. This included the documentation of rock textures, barchan dunes, soil crusts, wind tails, and ventifacts. It is expected that the Marie Curie rover cameras will also successfully return important information on landing site geology. Critical to a proper analysis of these images will be a rigorous determination of rover location and orientation. Here, the methods that were used to compute rover position for Sojourner image analysis are reviewed. Based on this experience, specific recommendations are made that should improve this process on the '01 mission.

Bridges, N. T.; Haldemann, A. F. C.; Herkenhoff, K. E.

1999-01-01

397

Midline governs axon pathfinding by coordinating expression of two major guidance systems.  

PubMed

Formation of the neural network requires concerted action of multiple axon guidance systems. How neurons orchestrate expression of multiple guidance genes is poorly understood. Here, we show that Drosophila T-box protein Midline controls expression of genes encoding components of two major guidance systems: Frazzled, ROBO, and Slit. In midline mutant, expression of all these molecules are reduced, resulting in severe axon guidance defects, whereas misexpression of Midline induces their expression. Midline is present on the promoter regions of these genes, indicating that Midline controls transcription directly. We propose that Midline controls axon pathfinding through coordinating the two guidance systems. PMID:19451216

Liu, Qing-Xin; Hiramoto, Masaki; Ueda, Hitoshi; Gojobori, Takashi; Hiromi, Yasushi; Hirose, Susumu

2009-05-15

398

Interior structure and seasonal mass redistribution of Mars from radio tracking of Mars Pathfinder.  

PubMed

Doppler and range measurements to the Mars Pathfinder lander made using its radio communications system have been combined with similar measurements from the Viking landers to estimate improved values of the precession of Mars' pole of rotation and the variation in Mars' rotation rate. The observed precession of -7576 +/- 35 milliarc seconds of angle per year implies a dense core and constrains possible models of interior composition. The estimated annual variation in rotation is in good agreement with a model of seasonal mass exchange of carbon dioxide between the atmosphere and ice caps. PMID:9388168

Folkner, W M; Yoder, C F; Yuan, D N; Standish, E M; Preston, R A

1997-12-01

399

Coralline reefs classification in Banco Chinchorro, Mexico  

NASA Astrophysics Data System (ADS)

The coralline reefs in Banco Chinchorro, Mexico, are part of the great reef belt of the western Atlantic. This reef complex is formed by an extensive coralline structure with great biological richness and diversity of species. These colonies are considered highly valuable ecologically, economically, socially and culturally, and they also inherently provide biological services. Fishing and scuba diving have been the main economic activities in this area for decades. However, in recent years, there has been a bleaching process and a decrease of the coral colonies in Quintana Roo, Mexico. This drop is caused mainly by the production activities performed in the oil platforms and the presence of hurricanes among other climatic events. The deterioration of the reef system can be analyzed synoptically using remote sensing. Thanks to this type of analysis, it is possible to have updated information of the reef conditions. In this paper, satellite imagery in Landsat TM and SPOT 5 is applied in the coralline reefs classification in the 1980- 2006 time period. Thus, an integral analysis of the optical components of the water surrounding the coralline reefs, such as on phytoplankton, sediments, yellow substance and even on the same water adjacent to the coral colonies, is performed. The use of a texture algorithm (Markov Random Field) was a key tool for their identification. This algorithm, does not limit itself to image segmentation, but also works on edge detection. In future work the multitemporal analysis of the results will determine the deterioration degree of these habitats and the conservation status of the coralline areas.

Contreras-Silva, Ameris I.; López-Caloca, Alejandra A.

2009-09-01

400

Upper Carboniferous reef mounds and climate change  

SciTech Connect

Tetractinomorph demosponges (chaetetids) are a minor component of extant tropical reefs, but they were the major framebuilder of reef mounds during the Westphalian (Carboniferous). These chaetetids were confined to tropical latitudes during the Carboniferous, reached an abundance peak in the Westphalian, and then declined suddenly until the Upper Triassic. After their decline, red and green algae became the dominant reef builders of the Stephanian. The marked decline of chaetetids corresponds with the disappearance, and/or decline of other marine benthic invertebrates, as well as some terrestrial plants and is the basis for the biostratigraphic boundary between the Westphalian and Stephanian (Desmoinesian and Missourian). This biostratigraphic boundary coincides with a minor extinction event and a major'' climatic change. The Westphalian climate was wetter than that of the Stephanian, and in the midcontinent this change is recorded by a gradual decline in coals and siliciclastic lithologies and a corresponding increase in carbonate lithologies. A rise in water temperature might be expected in a drier tropical climate, and if extant chaetetids are any clue, elevated water temperature may have been detrimental. Extant chaetetids are associated with tropical coral reefs that are confined to a narrow temperature range. It is not unreasonable to suggest that elevated seawater temperatures were responsible, in part, for the disappearance of chaetetid reef mounds. Red and green algae, presumably more tolerate of higher water temperatures, became the major framebuilders of reef mounds in the Stephanian. Thus, the demise of chaetetid reef mounds, and other organisms at the end of the Westphalian, may be the result of global warming.

West, R.R.; Archer, A.W. (Kansas State Univ., Manhattan, KS (United States))

1992-01-01

401

Reef-sourced slope deposits, Holocene, Bahamas  

SciTech Connect

Observations and sampling to 350 m from a two-person submersible off Chub Cay, Berry Island, Bahamas, support the idea that the Holocene deep reef is a principal source of talus, now cemented, that foots the windward margins of Great Bahama Bank. At the Chub Cay dive site, a wall extends from 30 to 170 m subsea; below is a low-relief fore reef slope, ca. 50/sup 0/, of limestone veneered with sediment. The upper wall from 30 to 80 m, the deep reef, has a luxuriant growth of corals and a profusion of the calcareous alga halimeda spp. Below 50 m, living coral decreases, and from 80 to 170 m the wall is highly irregular with discontinuous ledges and blind-end caves. At depths from 150 to 170 m, the wall gives way to the fore reef slope whose relative smooth surface dips at 50/sup 0/ to 60/sup 0/ and extends to 350 m. The fore reef is limestone, but its topography resembles that of alluvial fans; rounded ridges rise a few meters above the intervening valleys that are tens of meters wide. The limestone surface has a discontinuous veneer of fine sediment and algal plates, and locally loose cobble and boulder-sized blocks of limestone. A sample of the limestone slope is of well-cemented coral clasts and skeletal sediment. They infer that the deep reef grows outward so rapidly that it caves periodically. The resulting debris bypasses the wall, but some is perched on the steep fore reef slope below where it is soon incorporated into the slope by submarine cementation.

Ginsburg, R.N.; Eberli, G.P.; Harris, P.M.; Slater, R.; Swart, P.K.

1987-05-01

402

Devonian Winnipegosis reefs of Manitoba outcrop belt - possible basin model  

SciTech Connect

Devonian Winnipegosis reefs crop out intermittently along a 350-km belt in southwestern Manitoba and represent an almost complete facies sequence ranging from central-basin reefs in the northwest to shelf-edge reefs in the southeast. In addition, structural complexities of the overlying Devonian strata mirror precisely the configuration of the underlying reefs. These outcrop data, supplemented by closely spaced stratigraphic core holes that have been sited specifically with respect to reef-controlled structures, permit development of a tentative reef model. Reef parameters are (a) size, from less than 0.5 km to a maximum of about 12 km; (b) shape, small pinnacle-type features to broad, irregular, flat-topped, atoll-like complexes, all with relatively steep margins (5/degrees/-20/degrees/); and (c) height, uniform in any given area, ranging from 40-50 m at shelf edge to 65-90 m in central basin areas. Internal reef structure shows flat central beds, and flank dips ranging from 20/degrees/ to 45/degrees/ or more in the most basinward reefs. Locally, reefs are abundantly fossiliferous, but organic framework is difficult to identify. Black bituminous mudstones in the interreef and reef-flank areas, with or without reef-derived carbonate detritus, are the only time-stratigraphic equivalents of the reefs. (The Ratner-type bituminous carbonate laminites appear to entirely postdate reef development.) Configuration of the steep-sided reefs and the well-defined shelf edge may have been controlled not only by organic (biohermal.) development, but also by anoxic containment resulting from restriction of lateral growth by anoxic bottom waters. Pinnacle reefs could thus have developed, in part, as anoxically contained pinnacle mounds rather than true bioherms.

McCabe, H.R.

1988-07-01

403

Oceanography and reefs of recent and Paleozoic tropical epeiric seas  

Microsoft Academic Search

Summary  The Java Sea, one of the few modern tropical epeiric seas, is used as an analogue to examine oceanography, stratigraphy, and\\u000a reefs of Devonian strata in the Appalachian and Michigan Basins. Nearshore patch reefs and offshore “pinnacle” reefs occur\\u000a in both the Java Sea and the Emsian-Eifelian Onondaga Formation in the Appalachian Basin. Nearshore patch reefs also occur\\u000a in the

Evan N. Edinger; St. Paul Copper; Michael J. Risk; Warsito Atmojo

2002-01-01

404

Optical spectra and pigmentation of Caribbean reef corals and macroalgae  

Microsoft Academic Search

Coastal reef degradation and widespread bleaching of corals, i.e. loss of pigments and\\/or symbiotic zooxanthellae, is increasing\\u000a globally. Remote sensing from boats, aircraft or satellites has great potential for assessing the extent of reef change, but\\u000a will require ground-verified spectral algorithims characteristic of healthy and degraded reef populations. We collected seven\\u000a species of Caribbean reef corals and also representative macroalgae

M. R. Myers; J. T. Hardy; C. H. Mazel; P. Dustan

1999-01-01

405

An automatic identification and monitoring system for coral reef fish  

NASA Astrophysics Data System (ADS)

To help gauge the health of coral reef ecosystems, we developed a prototype of an underwater camera module to automatically census reef fish populations. Recognition challenges include pose and lighting variations, complicated backgrounds, within-species color variations and within-family similarities among species. An open frame holds two cameras, LED lights, and two `background' panels in an L-shaped configuration. High-resolution cameras send sequences of 300 synchronized image pairs at 10 fps to an on-shore PC. Approximately 200 sequences containing fish were recorded at the New York Aquarium's Glover's Reef exhibit. These contained eight `common' species with 85-672 images, and eight `rare' species with 5-27 images that were grouped into an `unknown/rare' category for classification. Image pre-processing included background modeling and subtraction, and tracking of fish across frames for depth estimation, pose correction, scaling, and disambiguation of overlapping fish. Shape features were obtained from PCA analysis of perimeter points, color features from opponent color histograms, and `banding' features from DCT of vertical projections. Images were classified to species using feedforward neural networks arranged in a three-level hierarchy in which errors remaining after each level are targeted by networks in the level below. Networks were trained and tested on independent image sets. Overall accuracy of species-specific identifications typically exceeded 96% across multiple training runs. A seaworthy version of our system will allow for population censuses with high temporal resolution, and therefore improved statistical power to detect trends. A network of such devices could provide an `early warning system' for coral ecosystem collapse.

Wilder, Joseph; Tonde, Chetan; Sundar, Ganesh; Huang, Ning; Barinov, Lev; Baxi, Jigesh; Bibby, James; Rapport, Andrew; Pavoni, Edward; Tsang, Serena; Garcia, Eri; Mateo, Felix; Lubansky, Tanya M.; Russell, Gareth J.

2012-10-01

406

BAG: A code for predicting the performance of a gas bag impact attenuation system for the PATHFINDER lander  

SciTech Connect

The National Aeronautics and Space Administration (NASA) is planning to launch a network of scientific probes to Mars beginning in late 1996. The precursor to this network will be PATHFINDER. Decelerating PATHFINDER from the high speed of its approach to Mars will require the use of several deceleration techniques working in series. The Jet Propulsion Laboratory (JPL) has proposed that gas bags be used to cushion the payload`s ground impact on Mars. This report presents the computer code, BAG, which has been developed to calculate the pneumatic performance of gas bag impact attenuators and the one-dimensional rigid-body dynamic performance of a payload during ground impact.

Cole, J.K.; Waye, D.E.

1993-11-01

407

Coral Reef Education and Australian High School Students  

ERIC Educational Resources Information Center

|Educational programs that focus on humans and their relationship to coral reefs are becoming necessary, as reef structures along the Queensland coast come under mounting ecological pressure. This paper reports on a PhD research project which investigated marine education and learning with high school students in coral reef environments along the…

Stepath, Carl M.

2004-01-01

408

Coral Reefs: A Gallery Program, Grades 7-12.  

ERIC Educational Resources Information Center

|Gallery classes at the National Aquarium in Baltimore give the opportunity to study specific aquarium exhibits which demonstrate entire natural habitats. The coral reef gallery class features the gigantic western Atlantic coral reef (325,000 gallons) with over 1,000 fish. The exhibit simulates a typical Caribbean coral reef and nearby sandy…

National Aquarium in Baltimore, MD. Dept. of Education.

409

Hindcast hurricane characteristics on the Belize barrier reef  

Microsoft Academic Search

Hurricane Greta was the most intense of the 1978 Atlantic hurricanes, with a minimum central pressure of 947 hPa (mb) just prior to passage across the Belize barrier reef in the western Caribbean. At Carrie Bow Cay, along the Belize barrier reef, 12 km south of the point where the storm crossed the barrier, coral reef damage was moderate and

B. Kjerfve; S. P. Dinnel

1983-01-01

410

Parrotfish predation on massive Porites on the Great Barrier Reef  

Microsoft Academic Search

Parrotfish grazing scars on coral colonies were quantified across four reef zones at Lizard Island, Northern Great Barrier\\u000a Reef (GBR). The abundance of parrotfish grazing scars was highest on reef flat and crest, with massive Porites spp. colonies having more parrotfish grazing scars than all other coral species combined. Massive Porites was the only coral type positively selected for grazing

R. M. Bonaldo; D. R. Bellwood

2011-01-01

411

Spectral unmixing of coral reef benthos under ideal conditions  

Microsoft Academic Search

Hyperspectral remote sensing has shown promise for detailed discrimination of coral reef substratum types, but, by necessity, it samples at pixel scales larger than reef substratum patch sizes. Spectral unmixing techniques have been successful in resolving subpixel areal cover in terrestrial environments. However, the application of spectral unmixing on coral reefs is fundamentally challenging, due not only to the water

J. D. Hedley; P. J. Mumby; K. E. Joyce; S. R. Phinn

2004-01-01

412

Watersheds and Coral Reefs: Conservation Science, Policy, and Implementation  

Microsoft Academic Search

Coral reefs worldwide are being degraded by human-induced disturbances, resulting in ecological, economic, and cultural losses. Runoff and sedimentation are among the greatest threats to the coastal reefs surrounding high islands and adjacent to continental landmasses. Existing scientific data identify the key stressors, synergisms, and outcomes at the coral reef ecosystem, community, and population levels. These data demonstrate that marine

ROBERT H. RICHMOND; TEINA RONGO; YIMNANG GOLBUU; STEVEN VICTOR; NOAH IDECHONG; GERRY DAVIS; WILLY KOSTKA; LEINSON NETH; MICHAEL HAMNETT; ERIC WOLANSKI

2007-01-01

413

Reef development at the Frasnian\\/Famennian mass extinction boundary  

Microsoft Academic Search

A newly compiled global reef database indicates that the 5–6 Myr long Frasnian (Late Devonian) metazoan reef episode had relatively low diversity compared to Middle Devonian highs (with over 200 genera of calcitic rugose and tabulate corals). Following an initial early rise after Late Givetian coral and stromatoporoid extinctions, reefs expanded for the last time during mid-Frasnian sealevel highstands, but

Paul Copper

2002-01-01

414

Declining Coral Calcification on the Great Barrier Reef  

Microsoft Academic Search

Reef-building corals are under increasing physiological stress from a changing climate and ocean absorption of increasing atmospheric carbon dioxide. We investigated 328 colonies of massive Porites corals from 69 reefs of the Great Barrier Reef (GBR) in Australia. Their skeletal records show that throughout the GBR, calcification has declined by 14.2% since 1990, predominantly because extension (linear growth) has declined

Glenn De'ath; Janice M. Lough; Katharina E. Fabricius

2009-01-01

415

Patterns in the use of space by benthic communities on two coral reefs of the Great Barrier Reef  

Microsoft Academic Search

A rapid benthic line-transect survey method for use by non-specialist observers is described. At both Davies Reef (mid-continental shelf) and Myrmidon Reef (outer-continental shelf) in the central Great Barrier Reef a set of 6 sites of varying depths on the reef flat, crest and slope were sampled using this method. At least 10 contiguous 10 m transects were made at

R. E. Reichelt; Y. Loya; R. H. Bradbury

1986-01-01

416

Water circulation in a fringing reef located in a monsoon area: Kabira Reef, Ishigaki Island, Southwest Japan  

Microsoft Academic Search

Kabira Reef is a well-developed fringing reef situated in a monsoon area where the dominant wind direction changes seasonally:\\u000a south in summer and north in winter. Circulation in this reef shows a marked wind influence. The circulation pattern under\\u000a calm wind conditions is characterized by an inflow of ocean waters into the moat over the reef crest and an outflow

H. Yamano; H. Kayanne; N. Yonekura; H. Nakamura; K. Kudo

1998-01-01

417

Charting a Course toward Diagnostic Monitoring: A Continuing Review of Coral Reef Attributes and a Research Strategy for Creating Coral Reef Indexes of Biotic Integrity.  

National Technical Information Service (NTIS)

This paper continues our review of coral reef attributes and presents a research strategy for creating coral reef indexes of biotic integrity (IBI's) that, once developed, can be used in coral reef biocriteria programs and for the diagnostic monitoring of...

S. C. Jamison M. V. Erdmann J. R. Karr G. R. Gibson K. W. Potts

2000-01-01

418

Colour vision in coral reef fish.  

PubMed

Over many millions of years, sea creatures have developed a range of light reflectance properties. One example is the large variation in the patterns and colours of fish inhabiting the world's coral reefs. Attempts to understand the significance of the colouration have been made, but all too often from the perspective of a human observer. A more ecological approach requires us to consider the visual system of those for whom the colours were intended, namely other sea life. A first step is to understand the sensitivity of reef fish themselves to colour. Physiological data has revealed wavelength-tuned photoreceptors in reef fish, and this study provides behavioural evidence for their application in colour discrimination. Using classical conditioning, freshly caught damselfish were trained to discriminate coloured patterns for a food reward. Within 3-4 days of capture the fish selected a target colour on over 75% of trials. Brightness of the distracter and target were systematically varied to confirm that the fish could discriminate stimuli on the basis of chromaticity alone. The study demonstrates that reef fish can learn to perform two-alternative discrimination tasks, and provides the first behavioural evidence that reef fish have colour vision. PMID:18203990

Siebeck, U E; Wallis, G M; Litherland, L

2008-02-01

419

Detecting ecological change on coral reefs  

NASA Astrophysics Data System (ADS)

Remote sensing offers the potential to observe the response of coral reef ecosystems to environmental perturbations on a geographical scale not previously accessible. However, coral reef environments are optically, spatially, and temporally complex habitats which all present significant challenges for extracting meaningful information. Virtually every member of the reef community possesses some degree of photosynthetic capability. The community thus generates a matrix of fine scale features with bio-optical signatures that blend as the scale of observation increases. Furthermore, to have any validity, the remotely sensed signal must be "calibrated" to the bio-optics of the reef, a difficult and resource intensive process due to a convergence of photosynthetic light harvesting by green, red, and brown algal pigment systems. To make matters more complex, reefs are overlain by a seawater skin with its own set of hydrological optical challenges. Rather than concentrating on classification, my research has attempted to track change by following the variation in geo-referenced pixel brightness over time with a technique termed temporal texture. Environmental periodicities impart a phenology to the variation in brightness and departures from the norm are easily detected as statistical outliers. This opens the door to using current orbiting technology to efficiently examine large areas of sea for change. If hot spots are detected, higher resolution sensors and field studies can be focused as resources permit. While this technique does not identify the type of change, it is sensitive, simple to compute, easy to automate and grounded in ecological niche theory

Dustan, P.

2011-12-01

420

Hawai'i Coral Reef Assessment and Monitoring Program: Spatial Patterns and Temporal Dynamics in Reef Coral Communities  

Microsoft Academic Search

The Hawai'i Coral Reef Assessment and Monitoring Program (CRAMP) was established to describe the spatial and temporal variation in Ha- waiian coral reef communities in relation to natural and anthropogenic factors. Sixty permanent reef sites stratified by depth have been monitored in the main Hawaiian Islands since 1999 and formed the basis for analysis of temporal change over the initial

Eric K. Brown; Alan Friedlander; S. Ku'ulei Rodgers; William R. Smith

2004-01-01

421

Reef Water CO2 System and Carbon Production of Coral Reefs: Topographic Control of System-Level Performance  

Microsoft Academic Search

The variations of seawater CO2 system and organic and inorganic carbon production of coral reefs were investigated with respect to topographic types and oceanographic settings. Because of dominant carbonate production in coral reef ecosystems, most coral reefs are likely to act as a net or at least a potential CO2 source to the atmosphere. The comparison of the seawater CO2

Atsushi SUZUKI; Hodaka KAWAHATA

2004-01-01

422

Measurements of the local energy balance over a coral reef flat, Heron Island, southern Great Barrier Reef, Australia  

Microsoft Academic Search

Coral reefs are thought to face significant threat from global warming due to increased water temperatures and ocean acidity. However, research into the surface energy balance of coral reefs and their associated micrometeorology is rare. Here we present, through a case study approach, the first direct in situ measurements of the surface energy balance of Heron Reef, a small platform

Hamish A. McGowan; Andrew P. Sturman; Melissa C. MacKellar; Andrew H. Wiebe; David T. Neil

2010-01-01

423

Luminescent lines in corals from the Great Barrier Reef provide spatial and temporal records of reefs affected by land runoff  

Microsoft Academic Search

The occurrence and intensity of luminescent lines was assessed by eye in slices from 232 similar-sized colonies of massive Porites from 30 reefs on the Great Barrier Reef (GBR), Australia. The reefs varied in location from coastal to 176 km from the mainland. Luminescent lines in corals of the GBR record periods when corals are exposed to river plumes and

J. M. Lough; D. J. Barnes; F. A. McAllister

2002-01-01

424

The Global Coral Reef Crisis: Trends and Solutions (Coral Reefs: Values, Threats, and the Marine Aquarium Trade)  

Microsoft Academic Search

Second only to tropical rainforests, coral reefs support one of the world's most diverse natural habitats. Over 350 million individuals depend on coral reef resources for food and income. Unfortunately, the Earth is in the midst of a coral reef crisis. Anthropogenic impacts including overfishing, destructive fishing practices, sedimentation and pollution, as well as global climate change, have served to

Craig S

2003-01-01

425

Coupling characterization and noise studies of the optical metrology system onboard the LISA Pathfinder mission  

SciTech Connect

We describe the first investigations of the complete engineering model of the optical metrology system (OMS), a key subsystem of the LISA Pathfinder science mission to space. The latter itself is a technological precursor mission to LISA, a spaceborne gravitational wave detector. At its core, the OMS consists of four heterodyne Mach-Zehnder interferometers, a highly stable laser with an external modulator, and a phase meter. It is designed to monitor and track the longitudinal motion and attitude of two floating test masses in the optical reference frame with (relative) precision in the picometer and nanorad range, respectively. We analyze sensor signal correlations and determine a physical sensor noise limit. The coupling parameters between motional degrees of freedom and interferometer signals are analytically derived and compared to measurements. We also measure adverse cross-coupling effects originating from system imperfections and limitations and describe algorithmic mitigation techniques to overcome some of them. Their impact on system performance is analyzed within the context of the Pathfinder mission.

Hechenblaikner, Gerald; Gerndt, Ruediger; Johann, Ulrich; Luetzow-Wentzky, Peter; Wand, Vinzenz; Audley, Heather; Danzmann, Karsten; Garcia-Marin, Antonio; Heinzel, Gerhard; Nofrarias, Miquel; Steier, Frank

2010-10-10

426

Geochemistry of Mars based on laboratoy analyses of Mars meteorites and in situ analyses from Pathfinder  

NASA Astrophysics Data System (ADS)

Using laboratory data on the composition of Mars meteorites, it was possible to make reliable estimates of the bulk composition of the Martian mantle and core. According to these estimates the Martian mantle contains, compared to the Earth's mantle, about twice as much FeO and also higher concentrations of moderately volatile and volatile elements. Also - contrary to the case of the Earth's mantle - Mn, Cr, and especially P are not depleted in the Martian mantle. All chalcophile elements were found to be highly depleted in the mantle of Mars and a homogeneous accretion of Mars was inferred. The core mass of Mars was estimated to 21%, consisting of Fe and Ni and about analyses of Martian rocks, which turned out to be rich in silica and potassium, but low in Mg resembling terrestrial andesites. The Martian soil which was found to have almost identical composition on all three sites where analyses were carried out, i.e. Viking 1, Viking 2, and Pathfinder. The soil can be explained as mechanical mixtures of diminuated basalts, compositionally similar to the Martian meteorites, their weathering products, as well as the andesitic component similar to the Pathfinder rocks. The APX-spectrometer was not able to detect carbon above the detection limit of 0.5 wt%, corresponding to about 5% carbonate.

Wänke, Heinrich

2002-10-01

427

adrift, a novel bnl-induced Drosophila gene, required for tracheal pathfinding into the CNS.  

PubMed

Neurons and glial cells provide guidance cues for migrating neurons. We show here that migrating epithelial cells also contact specific neurons and glia during their pathfinding, and we describe the first gene required in the process. In wild-type Drosophila embryos, the ganglionic tracheal branch navigates a remarkably complex path along specific neural and glial substrata, switching substrata five times before reaching its ultimate target in the CNS. In adrift mutants, ganglionic branches migrate normally along the intersegmental nerve, but sporadically fail to switch to the segmental nerve and enter the CNS; they wind up meandering along the ventral epidermis instead. adrift encodes a novel nuclear protein with an evolutionarily conserved motif. The gene is required in the trachea and is expressed in the leading cells of migrating ganglionic branches where it is induced by the branchless FGF pathway. We propose that Adrift regulates expression of tracheal genes required for pathfinding on the segmental nerve, and FGF induction of adrift expression in migrating tracheal cells promotes the switch from the intersegmental to the segmental nerve. PMID:10068643

Englund, C; Uv, A E; Cantera, R; Mathies, L D; Krasnow, M A; Samakovlis, C

1999-04-01

428

Overview of the development of the pathfinder ultra long duration balloon system  

NASA Astrophysics Data System (ADS)

The Ultra Long Duration Balloon (ULDB) Pathfinder Project is developing a small pumpkin balloon system and new payload support systems to demonstrate a global 100 day duration capability that is scalable to a full scale flight. The proposed 56,600 m3 pumpkin balloon will be capable of supporting a small tracking payload on the order of 20-40 kg, to an altitude of 24 to 33 km. The Pathfinder Test Balloons will provide valuable data in the development of performance models for future ULDB flights. Attempts will be made to design and fabricate the balloons as close as possible to the full scale ULDB in order to maintain conformity and accuracy of the two balloons' performance models. The balloon system will be designed to handle a small global command and telemetry payload also under development. The payload will include a photo-voltaic power system, command and data handling unit, GPS receiver, and IRIDIUM transceiver for global communications. The flight data will include, at a minimum, position (latitude, longitude, and altitude), and time as well as other balloon performance parameters. Although the system will be designed for global launch capability, initial flights will be launched from the proposed full-scale ULDB mission launch locations. The overall project objectives as well as the trade studies for determining the balloon design parameters, performance, system power requirements, data transmission rates, termination options and overall system configuration will be discussed.

Said, M.; Stuchlik, D.; Corbin, B.

429

Time domain maximum likelihood parameter estimation in LISA Pathfinder data analysis  

NASA Astrophysics Data System (ADS)

LISA is the upcoming space-based gravitational-wave detector. LISA Pathfinder, to be launched in the coming years, will be the in-flight test of the LISA arm, with a hardware (control scheme, sensors, and actuators) identical in design to LISA. LISA Pathfinder will collect a picture of all noise disturbances possibly affecting LISA, achieving the unprecedented pureness of geodesic motion of test masses necessary for the detection of gravitational waves. The first steps of both missions will crucially depend on a very precise calibration of the key system parameters. Moreover, robust parameters estimation has a fundamental importance in the correct assessment of the residual acceleration noise between the test masses, an essential part of the data preprocessing for LISA. In this paper, we present a maximum likelihood parameter estimation technique in time domain employed for system identification, being devised for this calibration, and show its proficiency on simulated data and validation through Monte Carlo realizations of independent noise runs. We discuss its robustness to nonstandard scenarios possibly arising during the real mission. Furthermore, we apply the same technique to data produced in missionlike fashion during operational exercises with a realistic simulator provided by European Space Agency. The result of the investigation is that parameter estimation is mandatory to avoid systematic errors in the estimated differential acceleration noise.

Congedo, G.; Ferraioli, L.; Hueller, M.; De Marchi, F.; Vitale, S.; Armano, M.; Hewitson, M.; Nofrarias, M.

2012-06-01

430

Juvenile coral reef fish use sound to locate habitats  

NASA Astrophysics Data System (ADS)

There is limited knowledge of the orientation cues used by reef fish in their movement among different habitats, especially those cues used during darkness. Although acoustic cues have been found to be important for settlement-stage fish as they seek settlement habitats, only a small number of studies support the possible role of acoustic cues in the orientation of post-settled and adult reef fish. Therefore, the aim of this study was to determine whether habitat-specific acoustic cues were involved in the nocturnal movements of juvenile reef fish to small experimental patch reefs that were broadcasting sound previously recorded from different habitats (Fringing Reef, Lagoon, Silent). Juvenile fish arriving at each patch reef were caught the next morning by divers and were identified. There were a greater number of occasions when juvenile fish (from all species together) moved onto the patch reefs broadcasting Fringing Reef and Lagoon sound (43 and 38%, respectively) compared to Silent reefs (19%) (?2 = 33.5; P < 0.05). There were significantly more occasions when juvenile fish from the family Nemipteridae were attracted to the patch reefs broadcasting Lagoon sound (63%) versus those reefs broadcasting either Fringing Reef sound (31%) or Silent (6%). In contrast, there were more occasions when juveniles from the family Pomacentridae were attracted to the patch reefs broadcasting Fringing Reef sound (56%) than either Lagoon (24%) or Silent patch reefs (20%) (?2 = 19.5; P < 0.05). These results indicate that some juvenile fish use specific habitat sounds to guide their nocturnal movements. Therefore, the fish are able to not only use the directional information contained in acoustic cues, but can also interpret the content of the acoustic signals for relevant habitat information which is then used in their decision-making for orientation.

Radford, C. A.; Stanley, J. A.; Simpson, S. D.; Jeffs, A. G.

2011-06-01

431

Does elevated pCO2 affect reef octocorals?  

PubMed Central

Increasing anthropogenic pCO2 alters seawater chemistry, with potentially severe consequences for coral reef growth and health. Octocorals are the second most important faunistic component in many reefs, often occupying 50% or more of the available substrate. Three species of octocorals from two families were studied in Eilat (Gulf of Aqaba), comprising the zooxanthellate Ovabunda macrospiculata and Heteroxenia fuscescens (family Xeniidae), and Sarcophyton sp. (family Alcyoniidae). They were maintained under normal (8.2) and reduced (7.6 and 7.3) pH conditions for up to 5 months. Their biolological features, including protein concentration, polyp weight, density of zooxanthellae, and their chlorophyll concentration per cell, as well as polyp pulsation rate, were examined under conditions more acidic than normal, in order to test the hypothesis that rising pCO2 would affect octocorals. The results indicate no statistically significant difference between the octocorals exposed to reduced pH values compared to the control. It is therefore suggested that the octocorals' tissue may act as a protective barrier against adverse pH conditions, thus maintaining them unharmed at high levels of pCO2.

Gabay, Yasmin; Benayahu, Yehuda; Fine, Maoz

2013-01-01

432

Determining trigger values of suspended sediment for behavioral changes in a coral reef fish.  

PubMed

Sediment from land use increases water turbidity and threatens the health of inshore coral reefs. This study performed experiments with a damselfish, Pomacentrus moluccensis, in four sediment treatments, control (0 mg l?¹), 10 mg l?¹ (?1.7 NTU), 20 mg l?¹ (?3.3 NTU) and 30 mg l?¹ (?5 NTU), to determine when sediment triggers a change in habitat use and movement. We reviewed the literature to assess how frequently P. moluccensis would experience sub-optimal sediment conditions on the reef. Preference for live coral declined from 49.4% to 23.3% and movement between habitats declined from 2.1 to 0.4 times between 20 mg l?¹ and 30 mg l?¹, suggesting a sediment threshold for behavioral changes. Inshore areas of the Great Barrier Reef, P. moluccensis may encounter sub-optimal conditions between 8% and 53% of the time. Changes in these vital processes may have long-term effects on the persistence of populations, particularly as habitat loss on coral reefs increases. PMID:23465624

Wenger, Amelia S; McCormick, Mark I

2013-03-05

433

The relative importance of local retention and inter-reef dispersal of neutrally buoyant material on coral reefs  

NASA Astrophysics Data System (ADS)

Reef-scale, eddy-resolving numerical models are applied to discriminate between local trapping of neutrally buoyant passive material coming from a natal reef versus trapping of this material on reefs downstream. A hydrodynamic model is coupled with a Lagrangian (nongridded) dispersal simulation to map the movement of material such as passive larvae within and between natural reefs. To simplify the interpretation, a number of schematic reef shapes, sizes and spacings were devised to represent the most common cases typifying Australia's Great Barrier Reef. Prior investigations have shown that coral reefs on the Great Barrier Reef may retain material for times equivalent to the pelagic dispersal period of many species. This paper explores whether larvae are more likely to settle on the natal reef, settle downstream or fail to settle at all. The modelling neglects active larval behaviour and treats the vertically well-mixed case of notionally weightless particles only. The crown-of-thorns starfish larvae with a pelagic dispersal period of at least 10 days are one example of this case. Larvae are most likely to be found near the natal reef rather than its downstream neighbour, mostly because the currents take the vertically well-mixed material around, rather than onto, the downstream reef. Of all the simulations, the highest numbers were found on natal reefs (e.g. 8% after 10 days) while downstream numbers mostly varied between 0 and 1% after 10 days. Particle numbers equalised only when spacing between the two reefs was less than the reef length (6 km), or when the downstream reef was in the direct path of the larval stream.

Black, Kerry P.

1993-03-01

434

Predicting the Location and Spatial Extent of Submerged Coral Reef Habitat in the Great Barrier Reef World Heritage Area, Australia  

PubMed Central

Aim Coral reef communities occurring in deeper waters have received little research effort compared to their shallow-water counterparts, and even such basic information as their location and extent are currently unknown throughout most of the world. Using the Great Barrier Reef as a case study, habitat suitability modelling is used to predict the distribution of deep-water coral reef communities on the Great Barrier Reef, Australia. We test the effectiveness of a range of geophysical and environmental variables for predicting the location of deep-water coral reef communities on the Great Barrier Reef. Location Great Barrier Reef, Australia. Methods Maximum entropy modelling is used to identify the spatial extent of two broad communities of habitat-forming megabenthos phototrophs and heterotrophs. Models were generated using combinations of geophysical substrate properties derived from multibeam bathymetry and environmental data derived from Bio-ORACLE, combined with georeferenced occurrence records of mesophotic coral communities from autonomous underwater vehicle, remotely operated vehicle and SCUBA surveys. Model results are used to estimate the total amount of mesophotic coral reef habitat on the GBR. Results Our models predict extensive but previously undocumented coral communities occurring both along the continental shelf-edge of the Great Barrier Reef and also on submerged reefs inside the lagoon. Habitat suitability for phototrophs is highest on submerged reefs along the outer-shelf and the deeper flanks of emergent reefs inside the GBR lagoon, while suitability for heterotrophs is highest in the deep waters along the shelf-edge. Models using only geophysical variables consistently outperformed models incorporating environmental data for both phototrophs and heterotrophs. Main Conclusion Extensive submerged coral reef communities that are currently undocumented are likely to occur throughout the Great Barrier Reef. High-quality bathymetry data can be used to identify these reefs, which may play an important role in resilience of the GBR ecosystem to climate change.

Bridge, Tom; Beaman, Robin; Done, Terry; Webster, Jody

2012-01-01

435

Preparing for Space-based Gravitational Wave Detection: LISA Pathfinder, the LISA Test Package, and ST7-DRS  

NASA Astrophysics Data System (ADS)

LISA Pathfinder is a dedicated technology demonstration mission for a future space-based observatory of gravitational waves in the milliHertz band. Although the formal NASA/ESA partnership on the LISA mission was dissolved in the Spring of 2011, both agencies are actively pursuing concepts for LISA-like gravitational wave observatories. These concepts take advantage of the significant technology development efforts that have already been made, especially those of the LISA Pathfinder mission. LISA Pathfinder, which is in the late stages of implementation, includes two scientific payloads: the European LISA Test Package (LTP) and the NASA-provided ST7-DRS. The mission will place two test masses in drag-free flight and measure the relative acceleration between them. This measurement will validate a number of technologies that are critical to LISA-like gravitational wave instruments including sensing and control of the test masses, drag-free control laws, micro-Newton thrusters, and picometer-level laser metrology. We will present the current status of the LISA Pathfinder mission and the LTP and ST7-DRS payloads.

Thorpe, James; Ziemer, J.; McNamara, P.; LPF Team; LTP Team; ST7-DRS Team

2013-01-01

436

Correction of AVHRR Pathfinder SST data for volcanic aerosol effects using ATSR SSTs and TOMS aerosol optical depth  

Microsoft Academic Search

The Pathfinder sea surface temperature (SST) data set, from the Advanced Very High Resolution Radiometer (AVHRR), is an important climate data record for SST due to the longevity of the sensor series of potentially 38years (from 1981 to 2020). However high amounts of aerosol in the atmosphere, such as after a major volcanic eruption, lead to a cool bias on

Thomas Blackmore; Anne O'Carroll; Karsten Fennig; Roger Saunders

437

Chemistry of the Martian Soils and Rocks at the Pathfinder Landing Site as Determined by the APXS  

Microsoft Academic Search

The chemical compositions of Martian rocks and soils examined with the Alpha Proton X-ray Spectrometer (APXS) during the Mars Pathfinder 1997 lander mission were not previously fully determined. Preliminary chemical results included major element abundances determined by the incomplete calibration of the X-ray mode. The data collected from the alpha and proton detectors were not previously analyzed due to significant

C. Foley; T. E. Economou; R. N. Clayton

2003-01-01

438

PATHFINDER ATOMIC POWER PLANT FINAL REPORT MOISTURE DE-ENTRAINMENT TESTS IN TWO AND FOUR-INCH DIAMETER TEST SECTIONS  

Microsoft Academic Search

Tests are described to determine the amount of entrained moisture ; occurring in the steam of the Pathfinder Power Plant as design parameters were ; varied. It was found that the height of the moisture separator and the velocity ; of the steam should be adjusted so that the permissible steam velocity for the ; particular height is not exceeded.

J. Wilson; M. McDermott

1959-01-01

439

Pupils' perceptions of foreign language learning in the primary school – findings from the Key Stage 2 Language Learning Pathfinder evaluation  

Microsoft Academic Search

This article presents findings on pupil attitudes towards learning foreign languages in Key Stage 2 (ages 7–11) in primary schools in England. As a consequence of the National Languages Strategy, the University of Warwick was commissioned by the then Department for Education and Skills to undertake an evaluation between 2003 and 2005 of 19 Pathfinder local authorities which were piloting

Cynthia Martin

2012-01-01

440

Silurian pinnacle reef distribution in Illinois: model for hydrocarbon exploration  

SciTech Connect

Approximately 92 million bbl of oil have been produced in Illinois from buried Silurian pinnacle reefs and from younger strata draped over these reefs. Better understanding of Silurian reef distribution and the use of appropriate exploration methods should lead to the discovery of new reef-associated hydrocarbon reserves. Evidence presented in this study suggest that Silurian pinnacle reef development was not limited to hinge-line trend around a subsiding basin center. Instead, isolated reefs grew through most of Illinois along a broad ramp dipping gently southeastward under a relatively shallow sea that opened to the south during the Silurian. Uplift of the Wabash platform in Indiana enabled concurrent pinnacle reef development along its flanks and formed the Fort Wayne and Terre Haute banks. These reef banks merged with and extended the scattered trends in Illinois. Erosion of Silurian strata prior to the Middle Devonian, particularly along the emerging Sangamon arch, removed or reduced the pinnacle reef structures across much of the central Illinois. These reef remnants are not easily detected by exploration methods commonly used in the basin, yet they can be oil-productive. Applications of geophysical and detailed lithologic surveys can greatly enhance the ability to locate these reefs.

Whitaker, S.T.

1987-09-01

441

Porosity controls in Late Jurassic algal reefs, Mississippi salt basin  

SciTech Connect

Reefs associated with high-rise salt structures that were active during Late Jurassic deposition (Smackover-Haynesville) have been the target of numerous deep tests in the Mississippi Salt basin. One such test, in Wayne County, Mississippi, encountered a 24-m reef. The reef exhibited no porosity or permeability, while sequences above (21 m) and below (24 m) were dolomitized, porous, and permeable. The reef sequence consists of a facies mosaic of encrusting to columnar massive red coralline algae, laminated to stromatolitic blue-green algae(.) with associated pelleted internal sediments and other features characteristic of modern framework reefs. The reef complex exhibits a strong early marine diagenetic overprint consisting of bladed to fibrous magnesian calcite(.) cements and botryoidal masses of magnesian calcite or aragonite. The lack of discernible freshwater diagenesis and the nature of t