Inexpensive in situ time-integrating seawater nutrient sampler

An in situ time-integrating seawater sampler in which air escaping from the sample bottle through a capillary regulates flow of seawater into the sampler is described for determination of average plant nutrient concentration during a 10–50 h period. The sampler collected water at a constant rate which was approximately equal to that predicted from the Hagen-Poiseuille equation. The sampler has advantages over those described previously: it is less susceptible to blockage from suspended particulates in seawater, less expensive, and the seawater collection rate should be less temperature-dependent.     

Elastic tubes—Assumptions, equations, edge conditions

This paper is concerned with further development of tube-analysis methods which are as simple as necessary for design and as accurate as possible in the shell theory. The basic assumptions are stated in Section 2. For ‘long’ tubes their accuracy is estimated in the course of derivation and simplification of nonlinear equations of axisymmetric flexure (Section 3). These equations and the estimates of the assumptions are extended to two-dimensional problems in Section 4. Equations of the semi-momentless theory encompassing shear deformation and appropriate edge conditions are discussed in Sections 5 and 6. Their solution, including a simple approximation, is in Sections 7–9 preceded by known calculations and experiment.     

A model psychosocial screening program for children and youth with newly diagnosed Type 1 diabetes: Implications for psychologists across contexts of care.

Psychosocial factors are strongly associated with long-term medical and mental health outcomes for children with Type 1 diabetes. As a result, current national and international guidelines now call for psychosocial screening at or near the time of diabetes diagnosis. Despite this recommendation, there are no published protocols to provide guidance to psychologists attempting to screen and identify at-risk patients and their families and prevent the emergence of secondary psychological and medical complications. In this article, the authors describe a model psychosocial screening program that was designed to minimize barriers to implementation and that can potentially be adapted for use by psychologists in different settings. Preliminary findings from the pilot phase of program development suggest that the screening is effective at identifying patients at risk for subsequent problems with diabetes management. The screening was able to identify specific, modifiable risk factors that provide targets for efforts at preventive intervention using treatment approaches familiar to most psychologists. The authors conclude with a discussion of the importance of screening and knowledge of diabetes risk factors for psychologists working in different treatment settings. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Effect of Friend leukemia virus on megakaryocytes and platelets in mice

The thrombocytopenia that follows infection of C3H/Bi mice with Friend leukemia virus (FV) has been investigated. At various times after infection, megakaryocytes in bone marrow and spleen were collected on Nuclepore filters, stained with the Feulgen procedure, and counted. At the same times, platelets in circulating blood were enumerated by the direct method of Brecher et al., 1963 We found that megakaryocyte numbers decreased within 3 days of infection; platelet numbers began to fall at 7 to 9 days. At 11 days megakaryocyte numbers in femoral marrow and spleen were reduced to less than one-third of control values, platelets to about one-quarter of control values. The data are compatible with the hypothesis that the thrombocytopenia which occurs after FV infection in mice results from the reduction in megakaryocytes that is brought about by the infection. Whether all classes of megakaryocytes are equally affected by FV was next examined. At various times following infection, megakaryocytes in marrow suspensions were concentrated by unit gravity sedimentation and microspectrophotometric measurements of nuclear DNA content were made. The kinetic data showed that, following FV infection, megakaryocytes of high nuclear DNA content were markedly reduced in number, but those of low nuclear DNA content were relatively unaffected. Thus the virus infection may interfere with the normal sequential doubling in DNA content of megakaryocytes and/or it may lead to preferential elimination by the host of those megakaryocytes in the higher DNA classes.     

Satellite attitude determination based on GPS signal-to-noise ratio

A method is presented for coarse attitude determination using the Global Positioning System (GPS) signal-to-noise ratio (SNR) from a single antenna mounted on a near-Earth satellite. It comprises a calibration procedure and a single-point optimal solution for the orientation of the antenna boresight vector. The calibration step creates an empirical mapping of the SNR to the angle between the antenna boresight and the GPS line-of-sight vector, based upon a ground or flight data set. The rms attitude accuracy at the level of 3°-10° is demonstrated with actual flight data from several spacecraft. Performance is shown to depend strongly on the number of GPS signals available and the quality of the calibration mapping function. The method is suitable as a backup attitude sensor for low-cost satellite and terrestrial applications, and as a coarse reference for ambiguity resolution and integrity verification of phase-based GPS attitude-determination algorithms     

A space-domain preconditioned spectral method for non-linear boundary value problems

A novel spectral procedure for the numerical solution of non-linear boundary value problems is presented. The discrete spectral equations are solved by an iterative algorithm using space-domain preconditioning. The preconditioning operator is obtained by spatial weighting (or windowing) of the exact differential operator. Convergence behaviour of the iterative solution is investigated using an eigenvalue analysis. Theoretical estimates for the convergence rate and accuracy are compared with that achieved in a numerical application—a non-linear boundary value problem from semiconductor device modelling. The method combines the infinite-order exponential accuracy of spectral discretizations with the sparse structure of finite difference equations. This offers numerical advantages in comparison to previously developed Fourier–Galerkin algorithms, particularly important for physically ill-conditioned and strongly non-linear problems. The tradeoff of achievable accuracy versus computer time is easily controlled, thus making essential speed-ups possible for moderate accuracy requirements.     

Lugaro cells target basket and stellate cells in the cerebellar cortex

Lugaro cells are fusiform neurons located just beneath the Purkinje cell layer. Their axon projects profusely in the molecular layer and emits some collaterals in the granular layer. We have analysed the molecular layer postsynaptic targets of a Golgi-impregnated Lugaro cell, using the electronmicroscopic gold-toning procedure and post-embedding anti-GABA immunocytochemistry. All the gold-labeled neuritic and somatic profiles were GABA-positive, thus confirming that the Lugaro cell is an inhibitory interneuron. The axonal varicosities of this cell form multiple symmetrical synaptic junctions with basket and stellate cell somata and proximal dendrites, and, perhaps, with the molecular layer dendrites of Golgi interneurons. Lugaro cells thus seem to exert a feed-back inhibitory control on Purkinje cells.     

Functional maturation of the somatosensory neocortex S1 in the rat. Electrophysiological and histochemical study (author's transl)

The functional maturation of the somatosensory neocortex has been studied using the projection areas of the whiskers. Natural stimulation of the whiskers evokes global potentials and unitary responses from the 4th postnatal day on. From the 2nd postnatal week the characteristics of the unit responses approximate in latency, topographic organisation of the projections, coding of the directions and temporal characteristics of the stimulation those of the adult. The histochemical activity of succinyl dehydrogenase is demonstrated in layer IV a little before the first electrophysiological response but the typical massed organisation is only seen from the 5th postnatal day. During maturation optical densitometry shows a rapid rise in enzyme activity untill the 7th postnatal day then a slower rise up to the 21st day after which it stabilises.     

Initial results of land-reflected GPS bistatic radar measurements in SMEX02

To investigate scattering of Global Positioning System (GPS) signals from terrain and the potential for remotely sensing soil moisture with the L-band GPS bistatic radar concept, a prototype GPS bistatic radar participated in airborne measurements during the Soil Moisture Experiment 2002 (SMEX02). A 12-channel GPS navigation receiver, modified to perform bistatic radar measurements, was mounted on the NCAR C-130 aircraft to make co-located measurements with other instruments. Narrow pulse returns and comparison of the reflected GPS signal-to-noise ratio (SNR) measurements to digital imagery and cover maps indicated that the scattering was most likely quasi-specular, originating from a small footprint on the order of the first Fresnel zone (∼30 m). Temporal changes were observed in the measured signals and were expected to be proportional to varying soil moisture content. To investigate this effect, the bistatic signal measurements were interpolated to a spatial grid to produce daily maps of relative change of surface soil moisture over the study region. The maps of the study region showed a transition from dry surface soil moisture conditions to wet conditions following precipitation events occurring in the middle of the study period. Additionally, the maps showed the scattered power increased in areas with localized rainfall relative to areas without precipitation. Comparing the GPS-reflected SNR measurements with L-band brightness temperatures measured coincidently by the PALS radiometer showed good agreement in the trend measured by the two sensors. The scattered signal measurements were also compared with in situ soil moisture measurements and found to follow the general soil moisture trend as a function of time. These initial results from the first controlled experiment of GPS bistatic radar for soil moisture remote sensing indicate that the technique is sensitive to temporal and spatial variations in soil moisture.