933 research outputs found
Come back Marshall, all is forgiven? : Complexity, evolution, mathematics and Marshallian exceptionalism
Marshall was the great synthesiser of neoclassical economics. Yet with his qualified assumption of self-interest, his emphasis on variation in economic evolution and his cautious attitude to the use of mathematics, Marshall differs fundamentally from other leading neoclassical contemporaries. Metaphors inspire more specific analogies and ontological assumptions, and Marshall used the guiding metaphor of Spencerian evolution. But unfortunately, the further development of a Marshallian evolutionary approach was undermined in part by theoretical problems within Spencer's theory. Yet some things can be salvaged from the Marshallian evolutionary vision. They may even be placed in a more viable Darwinian framework.Peer reviewedFinal Accepted Versio
Narrow genetic base in forest restoration with holm oak (Quercus ilex L.) in Sicily
In order to empirically assess the effect of actual seed sampling strategy on
genetic diversity of holm oak (Quercus ilex) forestations in Sicily, we have
analysed the genetic composition of two seedling lots (nursery stock and
plantation) and their known natural seed origin stand by means of six nuclear
microsatellite loci. Significant reduction in genetic diversity and significant
difference in genetic composition of the seedling lots compared to the seed
origin stand were detected. The female and the total effective number of
parents were quantified by means of maternity assignment of seedlings and
temporal changes in allele frequencies. Extremely low effective maternity
numbers were estimated (Nfe 2-4) and estimates accounting for both
seed and pollen donors gave also low values (Ne 35-50). These values
can be explained by an inappropriate forestry seed harvest strategy limited to
a small number of spatially close trees
Neurotrophic Effect of Citrus 5-Hydroxy-3,6,7,8,3âČ,4âČ-Hexamethoxyflavone: Promotion of Neurite Outgrowth via cAMP/PKA/CREB Pathway in PC12 Cells
5-Hydroxy-3,6,7,8,3âČ,4âČ-hexamethoxyflavone (5-OH-HxMF), a hydroxylated polymethoxyflavone, is found exclusively in the Citrus genus, particularly in the peels of sweet orange. In this research, we report the first investigation of the neurotrophic effects and mechanism of 5-OH-HxMF in PC12 pheochromocytoma cells. We found that 5-OH-HxMF can effectively induce PC12 neurite outgrowth accompanied with the expression of neuronal differentiation marker protein growth-associated protein-43(GAP-43). 5-OH-HxMF caused the enhancement of cyclic AMP response element binding protein (CREB) phosphorylation, c-fos gene expression and CRE-mediated transcription, which was inhibited by 2-naphthol AS-E phosphate (KG-501), a specific antagonist for the CREB-CBP complex formation. Moreover, 5-OH-HxMF-induced both CRE transcription activity and neurite outgrowth were inhibited by adenylate cyclase and protein kinase A (PKA) inhibitor, but not MEK1/2, protein kinase C (PKC), phosphatidylinositol 3-kinase (PI3K) or calcium/calmodulin-dependent protein kinase (CaMK) inhibitor. Consistently, 5-OH-HxMF treatment increased the intracellular cAMP level and downstream component, PKA activity. We also found that addition of K252a, a TrKA antagonist, significantly inhibited NGF- but not 5-OH-HxMF-induced neurite outgrowth. These results reveal for the first time that 5-OH-HxMF is an effective neurotrophic agent and its effect is mainly through a cAMP/PKA-dependent, but TrKA-independent, signaling pathway coupling with CRE-mediated gene transcription. A PKC-dependent and CREB-independent pathway was also involved in its neurotrophic action
The effect of blue light exposure in an ocular melanoma animal model
<p>Abstract</p> <p>Background</p> <p>Uveal melanoma (UM) cell lines, when exposed to blue light in vitro, show a significant increase in proliferation. In order to determine if similar effects could be seen in vivo, we investigated the effect of blue light exposure in a xenograft animal model of UM.</p> <p>Methods</p> <p>Twenty New Zealand albino rabbits were injected with 1.0 Ă 10<sup>6 </sup>human UM cells (92.1) in the suprachoroidal space of the right eye. Animals were equally divided into two groups; the experimental group was exposed to blue light, while the control group was protected from blue light exposure. The eyes were enucleated after sacrifice and the proliferation rates of the re-cultured tumor cells were assessed using a Sulforhodamine-B assay. Cells were re-cultured for 1 passage only in order to maintain any in vivo cellular changes. Furthermore, Proliferating Cell Nuclear Antigen (PCNA) protein expression was used to ascertain differences in cellular proliferation between both groups in formalin-fixed, paraffin-embedded eyes (FFPE).</p> <p>Results</p> <p>Blue light exposure led to a statistically significant increase in proliferation for cell lines derived from intraocular tumors (p < 0.01). PCNA expression was significantly higher in the FFPE blue light treated group when compared to controls (p = 0.0096).</p> <p>Conclusion</p> <p>There is an increasing amount of data suggesting that blue light exposure may influence the progression of UM. Our results support this notion and warrant further studies to evaluate the ability of blue light filtering lenses to slow disease progression in UM patients.</p
Theoretical overview on high-energy emission in microquasars
Microquasar (MQ) jets are sites of particle acceleration and synchrotron
emission. Such synchrotron radiation has been detected coming from jet regions
of different spatial scales, which for the instruments at work nowadays appear
as compact radio cores, slightly resolved radio jets, or (very) extended
structures. Because of the presence of relativistic particles and dense photon,
magnetic and matter fields, these outflows are also the best candidates to
generate the very high-energy (VHE) gamma-rays detected coming from two of
these objects, LS 5039 and LS I +61 303, and may be contributing significantly
to the X-rays emitted from the MQ core. In addition, beside electromagnetic
radiation, jets at different scales are producing some amount of leptonic and
hadronic cosmic rays (CR), and evidences of neutrino production in these
objects may be eventually found. In this work, we review on the different
physical processes that may be at work in or related to MQ jets. The jet
regions capable to produce significant amounts of emission at different
wavelengths have been reduced to the jet base, the jet at scales of the order
of the size of the system orbital semi-major axis, the jet middle scales (the
resolved radio jets), and the jet termination point. The surroundings of the
jet could be sites of multiwavelegnth emission as well, deserving also an
insight. We focus on those scenarios, either hadronic or leptonic, in which it
seems more plausible to generate both photons from radio to VHE and high-energy
neutrinos. We briefly comment as well on the relevance of MQ as possible
contributors to the galactic CR in the GeV-PeV range.Comment: Astrophysics & Space Science, in press (invited talk in the
conference: The multimessenger approach to the high-energy gamma-ray
sources", Barcelona/Catalonia, in July 4-7); 10 pages, 6 figures, 2 tables
(one reference corrected
Simultaneous Quantitation of Amino Acid Mixtures using Clustering Agents
A method that uses the abundances of large clusters formed in electrospray ionization to determine the solution-phase molar fractions of amino acids in multi-component mixtures is demonstrated. For solutions containing either four or 10 amino acids, the relative abundances of protonated molecules differed from their solution-phase molar fractions by up to 30-fold and 100-fold, respectively. For the four-component mixtures, the molar fractions determined from the abundances of larger clusters consisting of 19 or more molecules were within 25% of the solution-phase molar fractions, indicating that the abundances and compositions of these clusters reflect the relative concentrations of these amino acids in solution, and that ionization and detection biases are significantly reduced. Lower accuracy was obtained for the 10-component mixtures where values determined from the cluster abundances were typically within a factor of three of their solution molar fractions. The lower accuracy of this method with the more complex mixtures may be due to specific clustering effects owing to the heterogeneity as a result of significantly different physical properties of the components, or it may be the result of lower S/N for the more heterogeneous clusters and not including the low-abundance more highly heterogeneous clusters in this analysis. Although not as accurate as using traditional standards, this clustering method may find applications when suitable standards are not readily available
Planck intermediate results. XXIX. All-sky dust modelling with Planck, IRAS, and WISE observations
We present all-sky modelling of the high resolution Planck, IRAS, and WISE
infrared (IR) observations using the physical dust model presented by Draine
and Li in 2007 (DL). We study the performance and results of this model, and
discuss implications for future dust modelling. The present work extends the DL
dust modelling carried out on nearby galaxies using Herschel and Spitzer data
to Galactic dust emission. We employ the DL dust model to generate maps of the
dust mass surface density, the optical extinction Av, and the starlight
intensity parametrized by Umin. The DL model reproduces the observed spectral
energy distribution (SED) satisfactorily over most of the sky, with small
deviations in the inner Galactic disk and in low ecliptic latitude areas. We
compare the DL optical extinction Av for the diffuse interstellar medium with
optical estimates for 2 10^5 quasi-stellar objects (QSOs) observed in the Sloan
digital sky survey. The DL Av estimates are larger than those determined
towards QSOs by a factor of about 2, which depends on Umin. The DL fitting
parameter Umin, effectively determined by the wavelength where the SED peaks,
appears to trace variations in the far-IR opacity of the dust grains per unit
Av, and not only in the starlight intensity. To circumvent the model
deficiency, we propose an empirical renormalization of the DL Av estimate,
dependent of Umin, which compensates for the systematic differences found with
QSO observations. This renormalization also brings into agreement the DL Av
estimates with those derived for molecular clouds from the near-IR colours of
stars in the 2 micron all sky survey. The DL model and the QSOs data are used
to compress the spectral information in the Planck and IRAS observations for
the diffuse ISM to a family of 20 SEDs normalized per Av, parameterized by
Umin, which may be used to test and empirically calibrate dust models.Comment: Final version that has appeared in A&
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Emergence of Groundnut ringspot virus and Tomato chlorotic spot virus in Vegetables in Florida and the Southeastern United States
Groundnut ringspot virus (GRSV) and Tomato chlorotic spot virus
(TCSV) are two emerging tospoviruses in Florida. In a survey of the
southeastern United States, GRSV and TCSV were frequently detected in
solanaceous crops and weeds with tospovirus-like symptoms in south
Florida, and occurred sympatrically with Tomato spotted wilt virus (TSWV)
in tomato and pepper in south Florida. TSWV was the only tospovirus
detected in other survey locations, with the exceptions of GRSV from tomato
(Solanum lycopersicum) in South Carolina and New York, both of
which are first reports. Impatiens (Impatiens walleriana) and lettuce
(Lactuca sativa) were the only non-solanaceous GRSV and/or TCSV
hosts identified in experimental host range studies. Little genetic diversity
was observed in GRSV and TCSV sequences, likely due to the recent
introductions of both viruses. All GRSV isolates characterized were reassortants
with the TCSV M RNA. In laboratory transmission studies,
Frankliniella schultzei was a more efficient vector of GRSV than F. occidentalis.
TCSV was acquired more efficiently than GRSV by F. occidentalis
but upon acquisition, transmission frequencies were similar. Further
spread of GRSV and TCSV in the United States is possible and detection
of mixed infections highlights the opportunity for additional reassortment
of tospovirus genomic RNAs
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