Net community production in the North Atlantic Ocean derived from Volunteer Observing Ship data

The magnitude of marine plankton net community production (NCP) is indicative of both the biologically driven exchange of carbon dioxide between the atmosphere and the surface ocean and the export of organic carbon from the surface ocean to the ocean interior. In this study the seasonal variability in the NCP of five biogeochemical regions in the North Atlantic was determined from measurements of surface water dissolved oxygen and dissolved inorganic carbon (DIC) sampled from a Volunteer Observing Ship (VOS). The magnitude of NCP derived from dissolved oxygen measurements (NCPinline image) was consistent with previous geochemical estimates of NCP in the North Atlantic, with an average annual NCPinline image of 9.5 ± 6.5 mmol O2 m−2 d−1. Annual NCPinline image did not vary significantly over 35° of latitude and was not significantly different from NCP derived from DIC measurements (NCPDIC). The relatively simple method described here is applicable to any VOS route on which surface water dissolved oxygen concentrations can be accurately measured, thus providing estimates of NCP at higher spatial and temporal resolution than currently achieved

Seasonal and spatial variability in plankton production and respiration in the Subtropical Gyres of the Atlantic Ocean

Euphotic zone plankton production (P) and respiration (R) were determined from the in vitro flux of dissolved oxygen during six latitudinal transects of the Atlantic Ocean, as part of the Atlantic Meridional Transect (AMT) programme. The transects traversed the North and South Atlantic Subtropical Gyres (N gyre, 18–38°N; S gyre, 11–35°S) in April–June and September–November 2003–2005. The route and timing of the cruises enabled the assessment of the seasonal variability of P, R and P/R in the N and S gyres, and the comparison of the previously unsampled N gyre centre with the more frequently sampled eastern edge of the gyre. Mean euphotic zone integrated rates (±SE) were P=63±23 (n=31), R=69±22 (n=30) mmol O2 m-2 d-1 in the N gyre; and P=58±26 (n=30), R=62±24 (n=30) mmol O2 m-2 d-1 in the S gyre. Overall, the N gyre was heterotrophic (R>P) and it was more heterotrophic than the S gyre, but the metabolic balance of both gyres changed with season. Both gyres were net heterotrophic in autumn, and balanced in spring. This seasonal contrast was most pronounced for the S gyre, because it was more autotrophic than the N gyre during spring. This may have arisen from differences in nitrate availability, because spring sampling in the S gyre coincided with periods of deep mixing to the nitracline, more frequently than spring sampling within the N gyre. Our results indicate that the N gyre is less heterotrophic than previous estimates suggested, and that there is an apparent decrease in R from the eastern edge to the centre of the N gyre, possibly indicative of an allochthonous organic carbon source to the east of the gyre

Predicting plankton net community production in the Atlantic Ocean

We present, test and implement two contrasting models to predict euphotic zone net community production (NCP), which are based on 14C primary production (PO14CP) to NCP relationships over two latitudinal (ca. 30°S–45°N) transects traversing highly productive and oligotrophic provinces of the Atlantic Ocean (NADR, CNRY, BENG, NAST-E, ETRA and SATL, Longhurst et al., 1995 [An estimation of global primary production in the ocean from satellite radiometer data. Journal of Plankton Research 17, 1245–1271]). The two models include similar ranges of PO14CP and community structure, but differ in the relative influence of allochthonous organic matter in the oligotrophic provinces. Both models were used to predict NCP from PO14CP measurements obtained during 11 local and three seasonal studies in the Atlantic, Pacific and Indian Oceans, and from satellite-derived estimates of PO14CP. Comparison of these NCP predictions with concurrent in situ measurements and geochemical estimates of NCP showed that geographic and annual patterns of NCP can only be predicted when the relative trophic importance of local vs. distant processes is similar in both modeled and predicted ecosystems. The system-dependent ability of our models to predict NCP seasonality suggests that trophic-level dynamics are stronger than differences in hydrodynamic regime, taxonomic composition and phytoplankton growth. The regional differences in the predictive power of both models confirm the existence of biogeographic differences in the scale of trophic dynamics, which impede the use of a single generalized equation to estimate global marine plankton NCP. This paper shows the potential of a systematic empirical approach to predict plankton NCP from local and satellite-derived P estimates

The community practice program at the University of Michigan, Ann Arbor, U. S. A.

– The Community Dentistry Department of the University of Michigan has coordinated a community practice program since fall 1971. The program provides a broad range of experiences, including work with penal institutions, a major hospital, homes for the retarded, rural and urban clinics, an institution training dental assistants, and a summer migrant program. The purpose of the third year field experiences is to allow dental students to observe the relationship of dental and other health problems to individuals and social groups in a community setting and to become familiar with factors affecting the distribution of dental disease. The senior year experiences afford students an opportunity to perform clinical dental procedures in a community health environment and to become aware of social, economic, political and cultural factors affecting dental health and dental practice. It has been found that combining clinically-related experiences with community-related experiences results in much higher student motivation and enthusiasm. All dental students are required to spend seven days on community practice during their junior and senior years. The school feels that these extramural experiences bring about an awareness of and interest in the many opportunities that exist for guiding a community toward better dental health.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72572/1/j.1600-0528.1974.tb01796.x.pd

Archiving multi-epoch data and the discovery of variables in the near infrared

We present a description of the design and usage of a new synoptic pipeline and database model for time series photometry in the VISTA Data Flow System (VDFS). All UKIRT-WFCAM data and most of the VISTA main survey data will be processed and archived by the VDFS. Much of these data are multi-epoch, useful for finding moving and variable objects. Our new database design allows the users to easily find rare objects of these types amongst the huge volume of data being produced by modern survey telescopes. Its effectiveness is demonstrated through examples using Data Release 5 of the UKIDSS Deep Extragalactic Survey (DXS) and the WFCAM standard star data. The synoptic pipeline provides additional quality control and calibration to these data in the process of generating accurate light-curves. We find that 0.6+-0.1% of stars and 2.3+-0.6% of galaxies in the UKIDSS-DXS with K<15 mag are variable with amplitudes \Delta K>0.015 magComment: 30 pages, 31 figures, MNRAS, in press Minor changes from previous version due to refereeing and proof-readin

The brightest high-latitude 12-micron IRAS sources

The Infrared Astronomical Satellite (IRAS) Point Source catalog was searched for sources brighter than 28 Jy (0 mag) at 12 μm with absolute galactic latitude greater than 30° excluding the Large Magellanic Cloud. The search resulted in 269 sources, two of which are the galaxies NGC 1068 and M82. The remaining 267 sources are identified with, or have infrared color indices consistent with late-type stars some of which show evidence of circumstellar dust shells. Seven sources are previously uncataloged stars. K and M stars without circumstellar dust shells, M stars with circumstellar dust shells, and carbon stars occupy well-defined regions of infrared color-color diagrams

High sensitivity of ultra-oligotrophic marine ecosystems to atmospheric nitrogen deposition

Using a model of plankton and organic-matter cycling we demonstrate that variable stoichiometric ratios can lead to a more than 5-fold higher sensitivity of simulated carbon export to atmospheric N deposition in the ultra-oligotrophic eastern part of the North Atlantic subtropical gyre compared to the westerly oligotrophic region near Bermuda, often used as a reference site for subtropical regions. Stronger nutrient limitation in the ultra-oligotrophic east causes higher phytoplankton C:N ratios and lower carbon assimilation efficiency of zooplankton in the model, which results in a higher export efficiency of carbon to the deep ocean compared to the less nutrient-limited western site. Our results indicate that previous estimates of oceanic carbon uptake associated with atmospheric nitrogen deposition may not be fully robust and that spatial variability in nutrient stress and ecological stoichiometry could significantly affect the biogeochemical impact of increasing atmospheric deposition of anthropogenic nitrogen

Experimental Wind-Tunnel Investigation of the Transonic Damping-in-Pitch Characteristics of Two Wing-Body Combinations

The results of an experimental wind-tunnel investigation of the damping in pitch of two wing-body combinations are presented. The tests were conducted in the Ames 14-foot transonic wind tunnel over a Mach number range from 0.60 to 1.18. Reynolds numbers varied from 2.3 million to 5.5 million. One model with a triangular wing of aspect ratio 2 having NACA 0003-63 sections was oscillated at an amplitude of 1.5 and a frequency of 17 cycles per second. The second model with a straight, tapered wing of aspect ratio 3 having 3-percent biconvex circular-arc sections was oscillated at an amplitude of 1.0 deg and a frequency of 21 cycles per second. The tests were made with the models at a mean angle of attack of 0 deg. The models were oscillated with a dynamic balance that was actuated by an electrohydraulic servo valve. The results of this investigation indicate the usefulness of this new apparatus. The experimental results of a previous damping-in-pitch investigation conducted in the Ames 6- by 6-foot supersonic wind tunnel at Mach numbers from 1.2 to 1.7 are included along with the theoretical results for this Mach number range. In the region of Mach numbers available for comparison, good agreement is shown to exist between the data obtained in the two facilities, except for some inconsistency in the slopes of the curves at M = 1.2 for the triangular wing. The results of this investigation clearly show that for the models tested the maximum values of the damping in pitch occur at Mach numbers very close to 1.0, and that abrupt changes in the pitch damping are encountered near sonic velocity

THE UTILIZATION OF MOUTH-PROTECTORS BY FRESHMAN FOOTBALL PLAYERS

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65782/1/j.1752-7325.1972.tb03937.x.pd