The outer surfaces of the shells of living marine gastropods are often colonized by other organisms. However, only one species, the sabellid worm Terebrasabella heterouncinata, is able to settle in ...the aperture of living gastropods. Native to South Africa, and introduced to California, this worm is a pest of abalone aquaculture and has been a threat to native gastropods in California. We investigated the intrinsic susceptibility of 15 marine gastropods from California to this apertural fouling organism. Intrinsic susceptibility was significantly different among gastropod species. Overall, caenogastropods tended to be more resistant than were the vetigastropods and patellogastropods. This suggests that variability in susceptibility could be due to characteristics associated with closely related gastropod hosts. However, this only partially explained the variation in susceptibility to individuals of T. heterouncinata. Intrinsic susceptibility was not associated with potential host species from similar habitats. We discuss host susceptibility to T. heterouncinata, including implications for potential control of this pest species, and for understanding factors enabling this polychaete to inhabit the apertural region, an area typically free of all other epibionts.
We have synthesized new and existing relative sea-level (RSL) data to produce a quality-controlled, spatially comprehensive database from the North Carolina coastline. The RSL database consists of 54 ...sea-level index points that are quantitatively related to an appropriate tide level and assigned an error estimate, and a further 33 limiting dates that confine the maximum and minimum elevations of RSL. The temporal distribution of the index points is very uneven with only five index points older than 4000
cal a BP, but the form of the Holocene sea-level trend is constrained by both terrestrial and marine limiting dates. The data illustrate RSL rapidly rising during the early and mid Holocene from an observed elevation of −35.7
±
1.1
m MSL at 11062–10576
cal a BP to −4.2
m
±
0.4
m MSL at 4240–3592
cal a BP.
We restricted comparisons between observations and predictions from the ICE-5G(VM2) with rotational feedback Glacial Isostatic Adjustment (GIA) model to the Late Holocene RSL (last 4000
cal a BP) because of the wealth of sea-level data during this time interval. The ICE-5G(VM2) model predicts significant spatial variations in RSL across North Carolina, thus we subdivided the observations into two regions. The model forecasts an increase in the rate of sea-level rise in Region 1 (Albemarle, Currituck, Roanoke, Croatan, and northern Pamlico sounds) compared to Region 2 (southern Pamlico, Core and Bogue sounds, and farther south to Wilmington). The observations show Late Holocene sea-level rising at 1.14
±
0.03
mm year
−1 and 0.82
±
0.02
mm year
−1 in Regions 1 and 2, respectively. The ICE-5G(VM2) predictions capture the general temporal trend of the observations, although there is an apparent misfit for index points older than 2000
cal a BP. It is presently unknown whether these misfits are caused by possible tectonic uplift associated with the mid-Carolina Platform High or a flaw in the GIA model. A comparison of local tide gauge data with the Late Holocene RSL trends from Regions 1 and 2 support the spatial variation in RSL across North Carolina, and imply an additional increase of mean sea level of greater than 2
mm year
−1 during the latter half of the 20th century; this is in general agreement with historical tide gauge and satellite altimetry data.
In 1993 an unusual sabellid polychaete was brought to our attention. It grossly deformed the shells of cultured abalones in some of the California abalone mariculture facilities. This worm is not ...native to California and was subsequently found in rocky intertidal and subtidal habitats in southern Africa, where it had not previously been recognized. The worm is hermaphroditic and has benthic larvae that are competent to settle within 12 h and soon secrete a mucous sheath. Development of the tentacular crown occurs within a week and generation time can be short, about one month. The worm has a unique association with host gastropods. Unlike all other known shell-fouling organisms, the sabellid routinely settles inside the aperture at the growing edge of the shell. The host responds by secreting a layer of nacre over the mucous sheath to form a tube enclosing the worm, whose crown of tentacles extends through the opening of the tube to the outer surface of the shell. Heavy infestations cause the cessation of linear growth of the host as prismatic shell deposition cannot be resumed after repeated settlement of larvae. The sabellid is not very host specific; many other California native gastropods are readily infested. Bivalves do not appear to be susceptible. Efforts to find a native California predator of the adult worms were not successful. The sabellid has caused great economic damage to some facilities commercially culturing abalones. An established population of this worm has been detected in California, and further risk of establishment and spread of this worm is great. Its unique biology suggests that it may be a useful experimental probe for studies of molluscan shell deposition and may also serve to reveal how molluscs defend themselves against organisms attempting to settle in and foul their apertures.
Gold nanorods are promising nanoparticle-orientation sensors because they exhibit wavelength and angle-dependent optical patterns in their differential interference contrast (DIC) microscopy images. ...In this paper, we report a finite-difference time-domain method to simulate DIC images using nanorods as model probes. First, we created a DIC image library of nanorods as a function of imaging wavelength and rotation angle that showed good agreement with experimental results. Second, we used this simulation tool to explain why the patterns inverted from bright to dark when the imaging wavelength increased from below to above the plasmon resonance of the nanorod. We found that this intensity inversion resulted from reversal in the electric field direction depending on wavelength relative to the nanorod plasmon resonance. Finally, we showed that this DIC contrast inversion is a general phenomenon by measuring and simulating DIC images from gold nanorods of different sizes and gold nanostars.
We investigate long-run Purchasing Power Parity with data from the current floating exchange rate period by using tests where stationarity and cointegration are the null, rather than the alternative, ...hypotheses. In most cases, we cannot reject either the null hypothesis of stationarity of the real exchange rate or the null of cointegration between the nominal exchange rate and the domestic and foreign price levels. This constitutes evidence of long-run Purchasing Power Parity because, using the same tests, we can reject the null of stationarity for the nominal exchange rate. Confirmation of the results is provided by a Monte Carlo study.
Early Cambrian Foraminifera from West Africa Culver, Stephen J.
Science (American Association for the Advancement of Science),
11/1991, Letnik:
254, Številka:
5032
Journal Article
Recenzirano
Agglutinated foraminifera have been recovered from siltstones in the Walidiala Valley, Taoudeni Basin, West Africa. Associated faunas suggest an Early Cambrian age for these strata. These now ...earliest known unequivocal foraminifera help constrain hypotheses concerning the origin of skeletalization at the beginning of the Phanerozoic.
An easily accessible real-time Web-based utility to assess patient risks of future emergency department (ED) visits can help the health care provider guide the allocation of resources to better ...manage higher-risk patient populations and thereby reduce unnecessary use of EDs.
Our main objective was to develop a Health Information Exchange-based, next 6-month ED risk surveillance system in the state of Maine.
Data on electronic medical record (EMR) encounters integrated by HealthInfoNet (HIN), Maine's Health Information Exchange, were used to develop the Web-based surveillance system for a population ED future 6-month risk prediction. To model, a retrospective cohort of 829,641 patients with comprehensive clinical histories from January 1 to December 31, 2012 was used for training and then tested with a prospective cohort of 875,979 patients from July 1, 2012, to June 30, 2013.
The multivariate statistical analysis identified 101 variables predictive of future defined 6-month risk of ED visit: 4 age groups, history of 8 different encounter types, history of 17 primary and 8 secondary diagnoses, 8 specific chronic diseases, 28 laboratory test results, history of 3 radiographic tests, and history of 25 outpatient prescription medications. The c-statistics for the retrospective and prospective cohorts were 0.739 and 0.732 respectively. Integration of our method into the HIN secure statewide data system in real time prospectively validated its performance. Cluster analysis in both the retrospective and prospective analyses revealed discrete subpopulations of high-risk patients, grouped around multiple "anchoring" demographics and chronic conditions. With the Web-based population risk-monitoring enterprise dashboards, the effectiveness of the active case finding algorithm has been validated by clinicians and caregivers in Maine.
The active case finding model and associated real-time Web-based app were designed to track the evolving nature of total population risk, in a longitudinal manner, for ED visits across all payers, all diseases, and all age groups. Therefore, providers can implement targeted care management strategies to the patient subgroups with similar patterns of clinical histories, driving the delivery of more efficient and effective health care interventions. To the best of our knowledge, this prospectively validated EMR-based, Web-based tool is the first one to allow real-time total population risk assessment for statewide ED visits.
We collected modern diatom samples from Currituck Barrier Island, Oregon Inlet and Pea Island marshes, Outer Banks, North Carolina, USA, which have different salinity regimes due to their varying ...distances from a major barrier island inlet. Multivariate analyses separate the saltmarsh diatom assemblages into distinct elevational zones, dominated by differing abundances of polyhalobous, mesohalobous and oligohalobous taxa, suggesting that the distribution of saltmarsh diatoms is a direct function of elevation, with the most important controlling factors being the duration and frequency of subaerial exposure.
We developed the first diatom-based transfer function for the east coast of North America to reconstruct former sea levels based upon the relationship between diatom assemblage and elevation. Results imply that this is possible to a precision of ±0.08
m, superior to most similar studies from temperate, mid-latitude environments. The transfer function is used to construct a relative sea-level curve from fossil assemblages from Salvo, North Carolina. These results suggest a sea-level rise of 0.7
m over the last c. 150
years, at an average of c. 3.7
mm year
−1. This is consistent with existing sea-level data, and illustrates the utility of the transfer function approach.
This paper presents a new, more detailed depth zonation of the northwestern Gulf of Mexico based on one of the best benthic foraminiferal data sets published. Fourteen depth-relatable zones defined ...at the generic level are recognized, six in the neritic interval, seven in the bathyal interval, and one restricted to abyssal depths. A test of the depth zonation using modern data shows that 90% of all samples are correctly classified. Slightly lower levels of reliability of classification for the bathyal versus the neritic interval are evident due to naturally occurring overlaps of generic depth distributions in the bathyal interval. The model was further tested using Neogene samples from two northwestern Gulf of Mexico wells. The results show that the new automated depth classification technique provides interpretations similar to depth estimates based on conventional approaches. Although it is difficult to compare new results against depth estimates rather than known depths, the new technique appears to provide considerable data that indicate where and when the possibilities of sea-level changes, subsidence, faulting, downslope transport, or downhole caving should be investigated.
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