Application of the NASA airborne oceanographic lidar to the mapping of chlorophyll and other organic pigments

Laser fluorosensing techniques used for the airborne measurement of chlorophyll a and other naturally occurring waterborne pigments are reviewed. Previous experiments demonstrating the utility of the airborne oceanographic lidar (AOL) for assessment of various marine parameters are briefly discussed. The configuration of the AOL during the NOAA/NASA Superflux experiments is described. The participation of the AOL in these experiments is presented and the preliminary results are discussed. The importance of multispectral receiving capability in a laser fluorosensing system for providing reproducible measurements over wide areas having spatial variations in water column transmittance properties is addressed. This capability minimizes the number of truthing points required and is usable even in shallow estuarine areas where resuspension of bottom sediment is common. Finally, problems encountered on the Superflux missions and the resulting limitations on the AOL data sets are addressed and feasible solutions to these problems are provided

Detection of Multiple Pathways in the Spinal Cord White Matter Using Q-Ball Imaging

International audienceHigh angular resolution MRI such as q-ball imaging (QBI) allows to recover complex white matter architecture. We applied this technique to an ex vivo spinal cord of one cat using a 3T scanner, 100 directions and b-values varying from 1000 to 3000 s/mm2. As a result, QBI can retrieve crossing fibre information, where the diffusion tensor imaging approach is constrained to a single diffusion direction. To our knowledge, this is the first study demonstrating the benefits of QBI in observing longitudinal, commissural and dorso-ventral fibres in the spinal cord. It is a first step towards in vivo characterization of the healthy and injured spinal cord using high angular resolution diffusion imaging (HARDI) and QBI

High frequency sampling of the 1984 spring bloom within the mid-Atlantic Bight: Synoptic shipboard, aircraft, and in situ perspectives of the SEEP-I experiment

Moorings of current meters, thermistors, transmissometers, and fluorometers on the mid-Atlantic shelf, south of Long Island, suggest a cumulative seaward export of perhaps 0.35 g C/sq m/day between the 80 and 120 m isobaths during February-April 1984. Such a horizontal loss of algal carbon over the lower third of the water column would be 23 to 78% of the March-April 1984 primary production. This physical carbon loss is similar to daily grazing losses from zooplankton of 32-40% of the algal fixation of carbon. Metabolic demands of the benthos could be met by just the estimated fecal pellet flux, without direct consumption of algal carbon, while bacterioplankton needs could be served by excretory release of dissolved organic matter during photosynthesis. Sediment traps tethered 10 m off the bottom at the 120 m isobath and 50 m above the 500 m isobath caught as much as 0.16 to 0.26 g C /sq m/day during March-April 1984, in reasonable agreement with the flux estimated from the other moored instruments

At what time does a quantum experiment have a result?

This paper provides a general method for defining a generalized quantum observable (or POVM) that supplies properly normalized conditional probabilities for the time of occurrence (i.e., of detection). This method treats the time of occurrence as a probabilistic variable whose value is to be determined by experiment and predicted by the Born rule. This avoids the problematic assumption that a question about the time at which an event occurs must be answered through instantaneous measurements of a projector by an observer, common to both Rovelli (1998) and Oppenheim et al. (2000). I also address the interpretation of experiments purporting to demonstrate the quantum Zeno effect, used by Oppenheim et al. (2000) to justify an inherent uncertainty for measurements of times.Comment: To appear in proceedings of 2015 ETH Zurich Workshop on Time in Physic

Not fitting in and getting out : psychological type and congregational satisfaction among Anglican churchgoers in England

Listening to the motivations reported by individuals for ceasing church attendance and becoming church leavers, Francis and Richter identified high on the list the sense of "not fitting in". Drawing on psychological type theory, several recent studies have documented the way in which some psychological types are over-represented in church congregations and other psychological types are under-represented. Bringing these two observations together, the present study tested the hypothesis that church congregations have created type-alike communities within which individuals displaying the opposite type preferences are more likely to feel marginalised and to display lower levels of satisfaction with the congregations they attend. Data were provided by 1867 churchgoers who completed a measure of psychological type, together with measures of frequency of attendance and congregational satisfaction. These data confirmed that congregations were weighted towards preferences for introversion, sensing, feeling and judging, and that individuals displaying the opposite preferences (especially intuition, thinking and perceiving) recorded lower levels of congregational satisfaction. The implications of these findings are discussed for promoting congregational retention by enhancing awareness of psychological type preferences among those who attend

Prospective surveillance of invasive group a streptococcal disease, Fiji, 2005-2007.

We undertook a prospective active surveillance study of invasive group A streptococcal (GAS) disease in Fiji over a 23-month period, 2005-2007. We identified 64 cases of invasive GAS disease, which represents an average annualized all-ages incidence of 9.9 cases/100,000 population per year (95% confidence interval [CI] 7.6-12.6). Rates were highest in those >65 years of age and in those <5 years, particularly in infants, for whom the incidence was 44.9/100,000 (95% CI 18.1-92.5). The case-fatality rate was 32% and was associated with increasing age and underlying coexisting disease, including diabetes and renal disease. Fifty-five of the GAS isolates underwent emm sequence typing; the types were highly diverse, with 38 different emm subtypes and no particular dominant type. Our data support the view that invasive GAS disease is common in developing countries and deserves increased public health attention

The adverse effects of reduced cerebral perfusion on cognition and brain structure in older adults with cardiovascular disease

BACKGROUND: It is well established that aging and vascular processes interact to disrupt cerebral hemodynamics in older adults. However, the independent effects of cerebral perfusion on neurocognitive function among older adults remain poorly understood. We examined the associations among cerebral perfusion, cognitive function, and brain structure in older adults with varying degrees of vascular disease using perfusion magnetic resonance imaging (MRI) arterial spin labeling (ASL). MATERIALS AND METHODS: 52 older adults underwent neuroimaging and were administered the Mini Mental State Examination (MMSE), the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and measures of attention/executive function. ASL and T1-weighted MRI were used to quantify total brain perfusion, total brain volume (TBV), and cortical thickness. RESULTS: Regression analyses showed reduced total brain perfusion was associated with poorer performance on the MMSE, RBANS total index, immediate and delayed memory composites, and Trail Making Test B. Reduced frontal lobe perfusion was associated with worse executive and memory function. A similar pattern emerged between temporal lobe perfusion and immediate memory. Regression analyses revealed that decreased total brain perfusion was associated with smaller TBV and mean cortical thickness. Regional effects of reduced total cerebral perfusion were found on temporal and parietal lobe volumes and frontal and temporal cortical thickness. DISCUSSION: Reduced cerebral perfusion is independently associated with poorer cognition, smaller TBV, and reduced cortical thickness in older adults. CONCLUSION: Prospective studies are needed to clarify patterns of cognitive decline and brain atrophy associated with cerebral hypoperfusion

Climbing Fiber Burst Size and Olivary Sub-threshold Oscillations in a Network Setting

The inferior olivary nucleus provides one of the two main inputs to the cerebellum: the so-called climbing fibers. Activation of climbing fibers is generally believed to be related to timing of motor commands and/or motor learning. Climbing fiber spikes lead to large all-or-none action potentials in cerebellar Purkinje cells, overriding any other ongoing activity and silencing these cells for a brief period of time afterwards. Empirical evidence shows that the climbing fiber can transmit a short burst of spikes as a result of an olivary cell somatic spike, potentially increasing the information being transferred to the cerebellum per climbing fiber activation. Previously reported results from in vitro studies suggested that the information encoded in the climbing fiber burst is related to the occurrence of the spike relative to the ongoing sub-threshold membrane potential oscillation of the olivary cell, i.e. that the phase of the oscillation is reflected in the size of the climbing fiber burst. We used a detailed three-compartmental model of an inferior olivary cell to further investigate the possible factors determining the size of the climbing fiber burst. Our findings suggest that the phase-dependency of the burst size is present but limited and that charge flow between soma and dendrite is a major determinant of the climbing fiber burst. From our findings it follows that phenomena such as cell ensemble synchrony can have a big effect on the climbing fiber burst size through dendrodendritic gap-junctional coupling between olivary cells

Stress surrounding projectile anchors

The explicit three-dimensional finite element computer program DYNA3D developed at the Lawrence Livermore National Laboratory was applied to the problem of numerical modeling penetration of anchor projectiles into seafloor rock media. An axisymmetric model is used to study the penetration process of normal impacts into nonlinear homogeneous target materials. Modeling technique is developed and described for rock anchor penetration studies. Computed stress distribution data are described which are applicable to future anchor holding capacity prediction. DYNA3D results are shown to consistently underestimate the penetration depth when compared with the two-dimensional program DYNA2D. DYNA2D penetration depths have been shown elsewhere to compare well with laboratory test data. Simulation time on a Sun 4/260 workstation was found to be approximately 24 hours with a carefully constructed model. DYNA3D can potentially provide a solution capability for highly complex penetration problems that involve nonlinear material response and three-dimensional effects in rock media. A discussion of analytical approaches featuring a demonstration of a particular cavity expansion theory is also included.Includes bibliographical references (leaves 40-42)California State University, Northridge. Department of Engineering

The evolution of meiotic recombination in vertebrates: the case of snakes

Comparisons among model organisms make clear that, despite the fundamental importance of recombination in sexually-reproducing species, the mechanisms by which it is directed to the genome can vary markedly. Notably, in mice and humans, recombination almost exclusively occurs where the protein PRDM9 binds DNA. In such species, fine-scale recombination rates along the genome are rapidly evolving, as shifts in PRDM9 binding affinity remodel the landscape. In other species such as birds or canids, PRDM9 has been lost and recombination occurs preferentially at promoter-like features, leading to the conservation of recombination rates over large evolutionary distances. Increased recombination near promoters is also seen in human and mouse knockouts for PRDM9, indicating that this mechanism is normally out-competed by PRDM9 binding. The rapid evolution of complete orthologs of PRDM9 in non-mammalian vertebrates suggests that the protein may play a similar role in directing recombination outside of mammals. In chapter 2 of this work, we test this hypothesis by focusing on the corn snake Pantherophis guttatus, a representative vertebrate species with a single, complete PRDM9 ortholog that is rapidly evolving. We improved the assembly and annotation of the corn snake reference genome and resequenced 24 unrelated corn snake samples to high coverage in order to infer historical recombination rates across the genome from patterns of linkage disequilibrium. We find evidence for elevated recombination around computationally predicted PRDM9 binding sites but, surprisingly, also near promoter features. To verify these findings, we resequenced two pedigrees, identified the PRDM9 alleles segregating in the families and called crossover events that occurred in the parents. This analysis confirmed that crossover events overlap both PRDM9 binding sites and promoter features more than expected by chance. Thus, unlike in mammalian species that rely on PRDM9, in corn snakes there appears to be a mixed use of PRDM9 binding sites and promoter like features, and we find evidence that the relative importance of these features differs between macro- and microchomosomes. We hypothesize that the dual usage of these features reflects a tug of war between PRDM9 and promoter features, whose strength in snakes and possibly other vertebrates has been shifted by changes to a gene that reads the histone modifications made by PRDM9, and likely other genes. In chapter 3, I discuss how follow-up experiments based on these observations could help answer long-standing questions related to the conditions under which PRDM9-directed recombination localization is favorable. Beyond the specific results, this work illustrates how the study of non-model organisms can inform our understanding of basic genetic mechanisms