A ship-based methodology for high precision atmospheric oxygen measurements and its application in the Southern Ocean region

A method for achieving continuous high precision measurements of atmospheric O-2 is presented based on a commercially available fuel-cell instrument, (Sable Systems, Oxzilla FC-II) with a precision of 7 per meg (approximately equivalent to 1.2 ppm) for a 6-min measurement. The Oxzilla was deployed on two voyages in the Western Pacific sector of the Southern Ocean, in February 2003 and in April 2004, making these the second set of continuous O-2 measurements ever made from a ship. The results show significant temporal variation in O-2, in the order of +/- 10 per meg over 6-hourly time intervals, and substantial spatial variation. Data from both voyages show an O-2 maximum centred on 50 degrees S, which is most likely to be the result of biologically driven O-2 outgassing in the region of subtropical convergence around New Zealand, and a decreasing O-2 trend towards Antarctica. O-2 from the ship-based measurements is elevated compared with measurements from the Scripps Institution of Oceanography flask-sampling network, and the O-2 maximum is also not captured in the network observations. This preliminary study shows that ship-based continuous measurements are a valuable addition to current fixed site sampling programmes for the understanding of ocean-atmosphere O-2 exchange processes. [References: 39

Atmospheric potential oxygen: New observations and their implications for some atmospheric and oceanic models

Measurements of atmospheric O2/N2 ratios and CO2 concentrations can be combined into a tracer known as atmospheric potential oxygen (APO ≈ O2/N2 + CO2) that is conservative with respect to terrestrial biological activity. Consequently, APO reflects primarily ocean biogeochemistry and atmospheric circulation. Building on the work of Stephens et al. (1998), we present a set of APO observations for the years 1996-2003 with unprecedented spatial coverage. Combining data from the Princeton and Scripps air sampling programs, the data set includes new observations collected from ships in the low-latitude Pacific. The data show a smaller interhemispheric APO gradient than was observed in past studies, and different structure within the hemispheres. These differences appear to be due primarily to real changes in the APO field over time. The data also show a significant maximum in APO near the equator. Following the approach of Gruber et al. (2001), we compare these observations with predictions of APO generated from ocean O2 and CO2 flux fields and forward models of atmospheric transport. Our model predictions differ from those of earlier modeling studies, reflecting primarily the choice of atmospheric transport model (TM3 in this study). The model predictions show generally good agreement with the observations, matching the size of the interhemispheric gradient, the approximate amplitude and extent of the equatorial maximum, and the amplitude and phasing of the seasonal APO cycle at most stations. Room for improvement remains. The agreement in the interhemispheric gradient appears to be coincidental; over the last decade, the true APO gradient has evolved to a value that is consistent with our time-independent model. In addition, the equatorial maximum is somewhat more pronounced in the data than the model. This may be due to overly vigorous model transport, or insufficient spatial resolution in the air-sea fluxes used in our modeling effort. Finally, the seasonal cycles predicted by the model of atmospheric transport show evidence of an excessive seasonal rectifier in the Aleutian Islands and smaller problems elsewhere. Copyright 2006 by the American Geophysical Union

The Asymptotic Number of Irreducible Partitions

A partition of [1, n] = {1,..., n} is called irreducible if no proper subinterval of [1, n] is a union of blocks. We determine the asymptotic relationship between the numbers of irreducible partitions, partitions without singleton blocks, and all partitions when the block sizes must lie in some specified set

(4-Cyano­phenolato)(subphthalocyaninato)boron1

The crystal structure of the title compound, C31H16BN7O, (CNPhO-BsubPc) is characterized by pairs of π–π stacking inter­actions between the concave faces of inversion-related BsubPc fragments with a centroid–centroid distance of 3.600 (1) Å. In addition, these pairs of mol­ecules are linked into chains along [101] through further weak π–π stacking inter­actions with a centroid–centroid distance of 3.8587 (9) Å. There are also weak C—H⋯π(arene) inter­actions within the chains

Changes In Cerebral White Matter, Vascular Risk And Cognition Across The Adult Lifespan

Numerous studies over the past decade have used diffusion tensor imaging (DTI) to examine associations between age, diffusion and anisotropy measures of cerebral white matter (WM), and cognitive performance. However, few have examined relationships between intra-individual change in DTI measures of WM and cognitive function. It is possible that the extant cross-sectional findings are a poor representation of age-related change in WM and cognition. The present study used latent difference-score modeling (LDM) to assess change over two years in DTI indices fractional anisotropy (FA), radial diffusivity (DR), axial diffusivity (DA) and mean diffusivity (MD). In addition, we examined the effects of WM change on concomitant change in age-sensitive cognitive domains, while controlling for individual differences in duration of hypertension treatment, a common marker of vascular risk. A sample of 96 healthy participants spanning the adult lifespan underwent DTI scanning and cognitive testing at baseline and following a two-year delay. Univariate LDM analyses showed cross-sectional associations between DTI measures and age did not accurately describe actual change in WM. Regions including the genu of the corpus callosum, forceps major, and forceps minor showed reliable reductions in FA and increases in MD. In addition, change differed between DR and DA, suggesting the importance of evaluating these measures separately, rather than relying solely on MD as an index of diffusivity. Comparison of change in DTI measures and memory revealed baseline individual differences in FA, DA, and DR in dorsal and ventral cingulum bundle predicted two-year change in associative memory, while baseline DR and FA in multiple regions predicted change in recognition performance. The present findings demonstrate the necessity of longitudinal evaluation of change in WM and cognition

Luther\u27s Theological Anthropology: A Decisive Break from Scholasticism

The debate between Martin Luther and the Medieval Scholastics was one of the most significant debates in both the Reformation as a movement and the development of western Christianity as a whole. While the debate is dominantly characterized in terms of the dispute over the doctrines of sin and grace, the dispute between Luther and the medieval scholastic theologians was not simply a dispute over these two central doctrines but was a clash of entire theological systems. Moreover, the dispute over the doctrine of man forms a more logically basic and decisive point of clash, as Luther constructs his positions on sin and justification in light of a specific anthropology which is radically different from the dominant scholastic anthropologies. By adopting a substantially Aristotelian anthropology, Aquinas and Scotus define the basic composition and nature of man in such a way that their respective resulting doctrine of sin leaves man\u27s fundamental nature unchanged by the Fall, resulting in a doctrine of justification that still slips into the framework of merit. In contrast, Luther critiques this ontological focus in philosophical anthropology in favor of a theological anthropology that exhibits a relational, eschatological focus. This re-articulation of the doctrine of man allows Luther to affirm a more radical, existentially significant doctrine of sin and consequently controls his emphasis on and formulation of the doctrine of unmerited grace

Interpreting the seasonal cycles of atmospheric oxygen and carbon dioxide concentrations at American Samoa Observatory

We present seven years of atmospheric O2/N2 ratio and CO2 concentration data measured from flask samples collected at American Samoa. These data are unusual, exhibiting higher short-term variability, and seasonal cycles not in phase with other sampling stations. The unique nature of atmospheric data from Samoa has been noted previously from measurements of CO2, methyl chloroform, and ozone. With our O2 data, we observe greater magnitude in the short-term variability, but, in contrast, no clear seasonal pattern to this variability. This we attribute to significant regional sources and sinks existing for O2 in both hemispheres, and a dependence on both the latitudinal and altitudinal origins of air masses. We also hypothesize that some samples exhibit a component of "older" air, demonstrating recirculation of air within the tropics. Our findings could be used to help constrain atmospheric transport models which are not well characterized in tropical regions

Dynamic modeling of practice effects across the healthy aging-Alzheimer’s disease continuum

Standardized tests of learning and memory are sensitive to changes associated with both aging and superimposed neurodegenerative diseases. Unfortunately, repeated behavioral test administration can be confounded by practice effects (PE), which may obscure declines in level of abilities and contribute to misdiagnoses. Growing evidence, however, suggests PE over successive longitudinal measurements may differentially predict cognitive status and risk for progressive decline associated with aging, mild cognitive impairment (MCI), and dementia. Thus, when viewed as a reflection of neurocognitive plasticity, PE may reveal residual abilities that can add to our understanding of age- and disease-related changes in learning and memory. The present study sought to evaluate differences in PE and verbal recall in a clinically characterized aging cohort assessed on multiple occasions over 3 years. Participants included 256 older adults recently diagnosed as cognitively unimpaired (CU; n = 126), or with MCI of amnestic (n = 65) or non-amnestic MCI (n = 2085), and multi-domain amnestic dementia of the Alzheimer’s type (DAT; n = 45). We applied a continuous time structural equation modeling (ctsem) approach to verbal recall performance on the Hopkins Verbal Learning Test in order to distinguish PE from individual occasion performance, coupled random changes, age trends, and differing measurement quality. Diagnoses of MCI and dementia were associated with lower recall performance on all trials, reduced PE gain per occasion, and differences in non-linear dynamic parameters. Practice self-feedback is a dynamic measure of the decay or acceleration in PE process changes over longitudinal occasions. As with PE and mean recall, estimated practice self-feedback followed a gradient from positive in CU participants to null in participants with diagnosed MCI and negative for those with dementia diagnoses. Evaluation of sensitivity models showed this pattern of variation in PE was largely unmodified by differences in age, sex, or educational attainment. These results show dynamic modeling of PE from longitudinal performance on standardized learning and memory tests can capture multiple aspects of behavioral changes in MCI and dementia. The present study provides a new perspective for modeling longitudinal change in verbal learning in clinical and cognitive aging research

The Administration of a Republican Form of Government (enforcement)

Panel on enforcement