3,931 research outputs found
Conical scan impact study. Volume 2: Small local user data processing facility
The impact of a conical scan versus a linear scan multispectral scanner (MSS) instrument on a small local-user data processing facility was studied. User data requirements were examined to determine the unique system rquirements for a low cost ground system (LCGS) compatible with the Earth Observatory Satellite (EOS) system. Candidate concepts were defined for the LCGS and preliminary designs were developed for selected concepts. The impact of a conical scan MSS versus a linear scan MSS was evaluated for the selected concepts. It was concluded that there are valid user requirements for the LCGS and, as a result of these requirements, the impact of the conical scanner is minimal, although some new hardware development for the LCGS is necessary to handle conical scan data
Quantitative extraction of Meiofauna: A comparison of two methods
Two methods for the quantitative extraction of meiofauna from natural sandy sediments were investigated and compared: Cobb's decanting and sieving technique and the Oostenbrink elutriator. Both techniques were more efficient with pre-fixed samples than with fresh samples. The results indicated that elutriation is the more reliable method due to its low variability, 7,5% for nematodes and 8,4% for harpacticoids and mystacocarids compared to 11,2% and 29,0% respectively in the case of decantation. However, with samples containing 3 000 to 5 000 animals per 200 cc, decantation yielded 25% more animals than elutriation
Detection of Leishmania infantum by PCR, serology and cellular immune response in a cohort study of Brazilian dogs
The sensitivity and specificity of PCR, serology (ELISA) and lymphoproliferative response to Leishmania antigen for the detection of Leishmania infantum infection were evaluated in a cohort of 126 dogs exposed to natural infection in Brazil. For PCR, Leishmania DNA from bone-marrow was amplified with both minicircle and ribosomal primers. The infection status and time of infection of each dog were estimated from longitudinal data. The sensitivity of PCR in parasite-positive samples was 98%. However, the overall sensitivity of PCR in post-infection samples, from dogs with confirmed infection, was only 68%. The sensitivity of PCR varied during the course of infection, being highest (78–88%) 0–135 days post-infection and declining to around 50% after 300 days. The sensitivity of PCR also varied between dogs, and was highest in sick dogs. The sensitivity of serology was similar in parasite-positive (84%), PCR-positive (86%) and post-infection (88%) samples. The sensitivity of serology varied during the course of infection, being lowest at the time of infection and high (93–100%) thereafter. Problems in determining the specificity of serology are discussed. The sensitivity and specificity of cellular responsiveness were low. These data suggest that PCR is most useful in detecting active or symptomatic infection, and that serology can be a more sensitive technique for the detection of all infected dogs
Connecting up strategy: are senior strategy directors a missing link?
With companies being exhorted to become more strategically agile and internally connected, this article examines the role of the Senior Strategy Director, the executive tasked specifically with internal strategy. In particular, it explores what they do, what specific capabilities they deploy to enable effective contribution to the company, and in what ways they facilitate the connectedness of strategy. An analysis of multiple interviews over time with Senior Strategy Directors of large companies shows the vital and challenging role these executives play in both shaping, connecting up, and executing strategy. This article identifies the particular capabilities necessary for Senior Strategy Directors to perform their role and shows how it all depends upon their skilful deployment. These findings have significant implications for understanding unfolding micro-processes of strategy in large organizations, for assumptions about the skills and capabilities necessary to be an effective Senior Strategy Director, and for business schools in terms of the content and style of strategy courses they provide
The spectrum of bicyclic antiautomorphisms of directed triple systems
AbstractA transitive triple, (a,b,c), is defined to be the set {(a,b),(b,c),(a,c)} of ordered pairs. A directed triple system of order v, DTS(v), is a pair (D,β), where D is a set of v points and β is a collection of transitive triples of pairwise distinct points of D such that any ordered pair of distinct points of D is contained in precisely one transitive triple of β. An antiautomorphism of a directed triple system, (D,β), is a permutation of D which maps β to β−1, where β−1={(c,b,a)|(a,b,c)∈β}. In this paper we complete the necessary and sufficient conditions for the existence of a directed triple system of order v admitting an antiautomorphism consisting of two cycles
Vertical gradients in the fauna and oxidation of two exposed sandy beaches
Vertical profiles of oxygenation and fauna were measured in two exposed sandy beaches. At the less exposed site the whole upper metre of sediment was oxidized although the redox potential discontinuity started at 85 cm. Meiofauna were concentrated in the upper 40 cm and protozoa in the upper 55 cm, but bacteria showed no distinct vertical drop-off in numbers. On a more exposed beach the upper 1,3 m was highly oxidized, with meiofauna concentrated in the upper 80 cm and protozoa in the upper 115 cm. Meiofauna and protozoan numbers correlated with oxygen tensions and redox values and with each other. It is suggested that small protozoans are an important food source for the meiofauna.Vertikale profiele van suurstofkonsentrasie en fauna is in twee oop sandstrande bepaal. By die meer beskutte strand was die hele boonste meter sediment geoksideer alhoewel die redokspotensiaal-diskontinu'rteit by 85 cm begin het. Meiofauna was in die boonste 40 cm gekonsentreer en protozoa in die boonste 55 cm, maar daar was nie 'n duidelike - afname in bakteriegetalie op dieper vlakke nie. In die geval van die meer blootgestelde strand was die boonste 1,3 m hoogs geoksideer. Meiofauna was in die boonste 80 cm en protozoa in die boonste 1,15 m gekonsentreer. Meiofauna- en protozoa- getalle het met suurstofkonsentrasies en redokswaardes sowel as met mekaar gekorreleer. Daar word voorgestel dat klein protozoa 'n belangrike voedselbron vir die meiofauna is
Finite Projective Spaces, Geometric Spreads of Lines and Multi-Qubits
Given a (2N - 1)-dimensional projective space over GF(2), PG(2N - 1, 2), and
its geometric spread of lines, there exists a remarkable mapping of this space
onto PG(N - 1, 4) where the lines of the spread correspond to the points and
subspaces spanned by pairs of lines to the lines of PG(N - 1, 4). Under such
mapping, a non-degenerate quadric surface of the former space has for its image
a non-singular Hermitian variety in the latter space, this quadric being {\it
hyperbolic} or {\it elliptic} in dependence on N being {\it even} or {\it odd},
respectively. We employ this property to show that generalized Pauli groups of
N-qubits also form two distinct families according to the parity of N and to
put the role of symmetric operators into a new perspective. The N=4 case is
taken to illustrate the issue.Comment: 3 pages, no figures/tables; V2 - short introductory paragraph added;
V3 - to appear in Int. J. Mod. Phys.
Lens magnification by CL0024+1654 in the U and R band
[ABRIDGED] We estimate the total mass distribution of the galaxy cluster
CL0024+1654 from the measured source depletion due to lens magnification in the
R band. Within a radius of 0.54Mpc/h, a total projected mass of
(8.1+/-3.2)*10^14 M_sol/h (EdS) is measured, which corresponds to a mass-
to-light ratio of M/L(B)=470+/-180. We compute the luminosity function of
CL0024+1654 in order to estimate contamination of the background source counts
from cluster galaxies. Three different magnification-based reconstruction
methods are employed using both local and non-local techniques. We have
modified the standard single power-law slope number count theory to incorporate
a break and applied this to our observations. Fitting analytical magnification
profiles of different cluster models to the observed number counts, we find
that the cluster is best described either by a NFW model with scale radius
r_s=334+/-191 kpc/h and normalisation kappa_s=0.23+/-0.08 or a power-law
profile with slope xi=0.61+/-0.11, central surface mass density
kappa_0=1.52+/-0.20 and assuming a core radius of r_core=35 kpc/h. The NFW
model predicts that the cumulative projected mass contained within a radius R
scales as M(<R)=2.9*10^14*(R/1')^[1.3-0.5lg (R/1')] M_sol/h. Finally, we have
exploited the fact that flux magnification effectively enables us to probe
deeper than the physical limiting magnitude of our observations in searching
for a change of slope in the U band number counts. We rule out both a total
flattening of the counts with a break up to U_AB<=26.6 and a change of slope,
reported by some studies, from dlog N/dm=0.4->0.15 up to U_AB<=26.4 with 95%
confidence.Comment: 19 pages, 12 figures, submitted to A&A. New version includes more
robust U band break analysis and contamination estimates, plus new plot
Inhibition of pancreatic cancer cell growth in vitro by the tyrphostin group of tyrosine kinase inhibitors.
Tyrphostins are a group of low molecular weight synthetic inhibitors of protein tyrosine kinases (PTK). The intracellular domains of the receptors for epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), insulin-like growth factor 1 (IGF-1) possess PTK activity. Since EGF, TGF-alpha and IGF-1 are considered to play an important role in the proliferation of pancreatic cancer cells, we studied the effects of tyrphostins on the growth of three human pancreatic cancer cell lines (MiaPaCa-2, Panc-1 and CAV). The tyrphostins AG17, T23 and T47 all inhibited EGF and serum-stimulated DNA synthesis. AG17 was found to be the most potent of these agents and caused a dose-dependent but reversible inhibition of cell growth. Furthermore using an immunoblotting procedure we also found AG17 to inhibit EGF-induced tyrosine phosphorylation in the MiaPaCa-2 cell line. Tyrosine kinase inhibitors may prove to be useful agents for the treatment of pancreatic cancer
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