39 research outputs found

    The Making of a Productivity Hotspot in the Coastal Ocean

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    Highly productive hotspots in the ocean often occur where complex physical forcing mechanisms lead to aggregation of primary and secondary producers. Understanding how hotspots persist, however, requires combining knowledge of the spatio-temporal linkages between geomorphology, physical forcing, and biological responses with the physiological requirements and movement of top predators.) off the Baja California peninsula, Mexico.We have identified the set of conditions that lead to a persistent top predator hotspot, which increases our understanding of how highly migratory species exploit productive regions of the ocean. These results will aid in the development of spatially and environmentally explicit management strategies for marine species of conservation concern

    Geology, geochemistry and earthquake history of Lƍ`ihi Seamount, Hawai`i

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    Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Chemie der Erde - Geochemistry 66 (2006): 81-108, doi:10.1016/j.chemer.2005.09.002.A half century of investigations are summarized here on the youngest Hawaiian volcano, Lƍ`ihi Seamount. It was discovered in 1952 following an earthquake swarm. Surveying in 1954 determined it has an elongate shape, which is the meaning of its Hawaiian name. Lƍ`ihi was mostly forgotten until two earthquake swarms in the 1970’s led to a dredging expedition in 1978, which recovered young lavas. This led to numerous expeditions to investigate the geology, geophysics, and geochemistry of this active volcano. Geophysical monitoring, including a realtime submarine observatory that continuously monitored Lƍ`ihi’s seismic activity for three months, captured some of the volcano’s earthquake swarms. The 1996 swarm, the largest recorded in Hawai`i, was preceded by at least one eruption and accompanied by the formation of a ~300-m deep pit crater, renewing interest in this submarine volcano. Seismic and petrologic data indicate that magma was stored in a ~8-9 km deep reservoir prior to the 1996 eruption. Studies on Lƍ`ihi have altered conceptual models for the growth of Hawaiian and other oceanic island volcanoes and led to a refined understanding of mantle plumes. Petrologic and geochemical studies of Lƍ`ihi lavas showed that the volcano taps a relatively primitive part of the Hawaiian plume, producing a wide range of magma compositions. These compositions have become progressively more silica-saturated with time reflecting higher degrees of partial melting as the volcano drifts towards the center of the hotspot. Seismic and bathymetric data have highlighted the importance of landsliding in the early formation of an ocean island volcano. Lƍ`ihi’s internal structure and eruptive behavior, however, cannot be fully understood without installing monitoring equipment directly on the volcano. The presence of hydrothermal activity at Lƍ`ihi was initially proposed based on nontronite deposits on dredged samples that indicated elevated temperatures (31oC), and on the detection of water temperature, methane and 3He anomalies, and clumps of benthic micro-organisms in the water column over the volcano in 1982. Submersible observations in 1987 confirmed a low temperature system (15-30oC) prior to the 1996 formation of Pele’s Pit. The sulfide mineral assemblage (wurtzite, pyrrhotite, and chalcopyrite) deposited after the pit crater collapsed are consistent with hydrothermal fluids >250oC. Vent temperatures have decreased to ~60oC during the 2004 dive season indicating the current phase of hydrothermal activity may be waning.This work was supported by a NSF grant to M. Garcia (OCE 97-29894)

    Fever in Geriatric Emergency Patients: Clinical Features Associated With Serious Illness

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    Study objective: To determine the clinical significance of fever in geriatric emergency department patients. Design: Case series with follow-up. Setting: Urban, university-affiliated community hospital. Participants: Consecutive patients over the age of 65 years who presented to the ED during a 12-month period with an oral temperature of 100.0°F (37.8°C) or higher. Results: We considered the following features indicators of serious illness: positive blood culture(s), related death within 1 month of ED visit, need for surgery or other invasive procedure, hospitalization for 4 or more days, IV antibiotics for 3 or more days, and repeat ED visit within 72 hours for related condition. Four hundred eighty-nine patients were eligible for study. Of the 470 patients with complete follow-up data, 357(76.0%) had indicators of serious illness. Clinical features found to be independently associated with serious illness included oral temperature of 103°F (39.4°C) or more, respiration rate of 30 or more, leukocytosis of 11.0×109/L or more, presence of an infiltrate, and pulse of 120 or more. At least one indicator of serious illness was present in 63 of 128 patients (49.6%) with none of these independently predictive clinical features. The most common final diagnoses were pneumonia (24.0%), urinary-tract infection (21.7%), and sepsis (12.8%). Conclusion: Fever among geriatric ED patients frequently marks the presence of serious illness. All such patients should be strongly considered for hospital admission, particularly when certain clinical features are present. The absence of abnormal findings does not reliably rule out the possibility of serious illness

    Fever in Geriatric Emergency Patients: Clinical Features Associated With Serious Illness

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    Study objective: To determine the clinical significance of fever in geriatric emergency department patients. Design: Case series with follow-up. Setting: Urban, university-affiliated community hospital. Participants: Consecutive patients over the age of 65 years who presented to the ED during a 12-month period with an oral temperature of 100.0°F (37.8°C) or higher. Results: We considered the following features indicators of serious illness: positive blood culture(s), related death within 1 month of ED visit, need for surgery or other invasive procedure, hospitalization for 4 or more days, IV antibiotics for 3 or more days, and repeat ED visit within 72 hours for related condition. Four hundred eighty-nine patients were eligible for study. Of the 470 patients with complete follow-up data, 357(76.0%) had indicators of serious illness. Clinical features found to be independently associated with serious illness included oral temperature of 103°F (39.4°C) or more, respiration rate of 30 or more, leukocytosis of 11.0×109/L or more, presence of an infiltrate, and pulse of 120 or more. At least one indicator of serious illness was present in 63 of 128 patients (49.6%) with none of these independently predictive clinical features. The most common final diagnoses were pneumonia (24.0%), urinary-tract infection (21.7%), and sepsis (12.8%). Conclusion: Fever among geriatric ED patients frequently marks the presence of serious illness. All such patients should be strongly considered for hospital admission, particularly when certain clinical features are present. The absence of abnormal findings does not reliably rule out the possibility of serious illness

    Valley Floor Climate Observations from the McMurdo Dry Valleys, Antarctica, 1986-2000

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    Climate observations from the McMurdo dry valleys, East Antarctica are presented from a network of seven valley floor automatic meteorological stations during the period 1986 to 2000. Mean annual temperatures ranged from −14.8°C to −30.0°C, depending on the site and period of measurement. Mean annual relative humidity is generally highest near the coast. Mean annual wind speed increases with proximity to the polar plateau. Site to site variation in mean annual solar flux and PAR is due to exposure of each station and changes over time are likely related to changes in cloudiness. During the non-summer months, strong katabatic winds are frequent at some sites and infrequent at others, creating large variation in mean annual temperature owing to the warming effect of the winds. Katabatic wind exposure appears to be controlled to a large degree by the presence of colder air in the region that collects at low points and keeps the warm less dense katabatic flow from the ground. The strong influence of katabatic winds makes prediction of relative mean annual temperature based on geographical position (elevation and distance from the coast) alone, not possible. During the summer months, onshore winds dominate and warm as they progress through the valleys creating a strong linear relationship (rÂČ = 0.992) of increasing potential temperature with distance from the coast (0.09°C km⁻Âč). In contrast to mean annual temperature, summer temperature lends itself quite well to model predictions, and is used to construct a statistical model for predicting summer dry valley temperatures at unmonitored sites
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