40,851 research outputs found

    Math modeling for helicopter simulation of low speed, low altitude and steeply descending flight

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    A math model was formulated to represent some of the aerodynamic effects of low speed, low altitude, and steeply descending flight. The formulation is intended to be consistent with the single rotor real time simulation model at NASA Ames Research Center. The effect of low speed, low altitude flight on main rotor downwash was obtained by assuming a uniform plus first harmonic inflow model and then by using wind tunnel data in the form of hub loads to solve for the inflow coefficients. The result was a set of tables for steady and first harmonic inflow coefficients as functions of ground proximity, angle of attack, and airspeed. The aerodynamics associated with steep descending flight in the vortex ring state were modeled by replacing the steady induced downwash derived from momentum theory with an experimentally derived value and by including a thrust fluctuations effect due to vortex shedding. Tables of the induced downwash and the magnitude of the thrust fluctuations were created as functions of angle of attack and airspeed

    A procedure for assessing aircraft turbulence- penetration performance

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    Subsonic transport aircraft performance assessment during atmospheric turbulenc

    Accessibility mapping in the Horn of Africa: Applications for livestock policy

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    Poverty and welfare measures in the Horn of Africa

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    A multiband radiometer and data acquisition system for remote sensing field research

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    Specifications are described for a recently developed prototype multispectral data acquisition system which consists of multiband radiometer with 8 bands between 0.4 and 12.5 micrometers and a data recording module to record data from the radometer and ancillary sources. The systems is adaptable to helicopter, truck, or tripod platforms, as well as hand-held operation. The general characteristics are: (1) comparatively inexpensive to acquire, maintain and operate; (2) simple to operate and calibrate; (3) complete with data hardware and software; and (4) well documented for use by researchers. The instrument system is to be commercially available and can be utilized by many researchers to obtain large numbers of accurate, calibrated spectral measurements. It can be a key element in improving and advancing the capability for field research in remote sensing

    RNA-seq reveals post-transcriptional regulation of Drosophila insulin-like peptide dilp8 and the neuropeptide-like precursor Nplp2 by the exoribonuclease Pacman/XRN1

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    Ribonucleases are critically important in many cellular and developmental processes and defects in their expression are associated with human disease. Pacman/XRN1 is a highly conserved cytoplasmic exoribonuclease which degrades RNAs in a 5' - 3' direction. In Drosophila, null mutations in pacman result in small imaginal discs, a delay in onset of pupariation and lethality during the early pupal stage. In this paper, we have used RNA-seq in a genome-wide search for mRNAs misregulated in pacman null wing imaginal discs. Only 4.2% of genes are misregulated ±>2-fold in pacman null mutants compared to controls, in line with previous work showing that Pacman has specificity for particular mRNAs. Further analysis of the most upregulated mRNAs showed that Pacman post-transcriptionally regulates the expression of the secreted insulin-like peptide Dilp8. Dilp8 is related to human IGF-1, and has been shown to co-ordinate tissue growth with developmental timing in Drosophila. The increased expression of Dilp8 is consistent with the developmental delay seen in pacman null mutants. Our analysis, together with our previous results, show that the normal role of this exoribonuclease in imaginal discs is to suppress the expression of transcripts that are crucial in apoptosis and growth control during normal development

    The child psychotherapists' role in consultation work with the professional network around looked after children

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    Consultation with the network around a child is a core aspect of a child psychotherapist’s role; however, little has been written about this aspect of their work with looked after children. Aims: To gain an understanding of child psychotherapists’ work with the network around looked after children, and what they see as specific to the psychoanalytic approach. Methods: Nine participants with expertise in working with foster carers and looked after children’s professionals, participated in in-depth interviews. Results: Thematic analysis identified three themes concerned with the tensions child psychotherapists hold within themselves whilst consulting to the network around looked after children. The first theme encapsulates participants’ sense of dilemma between what they felt was demanded of them versus what they could offer. The second theme describes participants’ sense of tensions around the way the system is organised versus what they felt is in the best interests of the child and network. The third theme captures participants’ views about whether their consultant role fits a generic model of reflective practice similar to that offered by professionals from other disciplines, or whether the psychoanalytic approach brings something distinctive to this model of consultation. Links to existing theory and practice implications are discussed

    Deep-sea scleractinian coral age and depth distributions in the Northwest Atlantic over the last 225,000 years

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    Journal ArticleDeep-sea corals have grown for over 200,000 yrs on the New England Seamounts in the northwest Atlantic, and this paper describes their distribution both with respect to depth and time. Many thousands of fossil scleractinian corals were collected on a series o f cruises from 2003- 2005; by contrast, live ones were scarce. On these seamounts, the depth distribution of fossil Desmophyllum dianthus (Esper, 1794) is markedly different to that oft he colonial scleractinian corals, extending 750m deeper in the water column to a distinct cut-off at 2500 m. This cut-off is likely to be controlled by the maximum depth of a notch-shaped feature in the seamount morphology. The ages of D. dianthus corals as determined by U-series measurements range from modern to older than 200,000 yrs. The age distribution is not constant over time, and most corals have ages from the last glacial period. Within the glacial period, increases in coral population density at Muir and Manning Seamounts coincided with times at which large-scale ocean circulation changes have been documented in the deep North Atlantic. Ocean circulation changes have an effect on coral distributions, but the cause of the link is not known
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