9,009 research outputs found
Short-Term Capital Flows, The Real Economy and Income Distribution in Developing Countries
The volatility of short-term capital flows (or 'capital surges') is now recognized as a major problem for macroeconomic management in developing countries; but the consequences for the 'real' economy - that is, the behaviour of government, firms and households which subsequently translates into investment, growth, employment and welfare - is less well understood. Short-term capital flow instability arises from the desire of investors to hold liquid assets in the face of uncertainty; affecting the real economy both through variations in both prices such as the interest rate and the exchange rate, and quantities such as levels of bank credit and government bond sales. In this chapter, government expenditure is shown to respond in an asymmetric manner to sudden changes in investor perceptions of fiscal solvency associated with portfolio capital surges. The impact of short flows on output and investment by firms through the availability of bank credit is also found to be large and asymmetric. The macroeconomic effect of capital surges on employment levels and the real wage rate is shown to arise from their influence on real exchange rates and domestic demand levels, although whether employment or wages adjust depends the monetary stabilization policy adopted. The chapter concludes with some implications of the analysis for longer-term growth and policy design.
An analysis of multi-meaning words from a selected list of third-grade textbooks,
Thesis (M.A.)--Boston Universit
A describing function analysis in closed loop systems with pulse frequency modulators
Describing functions for stability analysis of integral pulse frequency modulated unity feedback closed loop syste
Quantum Plasmonics
Quantum plasmonics is an exciting subbranch of nanoplasmonics where the laws of quantum theory are used to describe light–matter interactions on the nanoscale. Plasmonic materials allow extreme subdiffraction confinement of (quantum or classical) light to regions so small that the quantization of both light and matter may be necessary for an accurate description. State-of-the-art experiments now allow us to probe these regimes and push existing theories to the limits which opens up the possibilities of exploring the nature of many-body collective oscillations as well as developing new plasmonic devices, which use the particle quality of light and the wave quality of matter, and have a wealth of potential applications in sensing, lasing, and quantum computing. This merging of fundamental condensed matter theory with application-rich electromagnetism (and a splash of quantum optics thrown in) gives rise to a fascinating area of modern physics that is still very much in its infancy. In this review, we discuss and compare the key models and experiments used to explore how the quantum nature of electrons impacts plasmonics in the context of quantum size corrections of localized plasmons and quantum tunneling between nanoparticle dimers. We also look at some of the remarkable experiments that are revealing the quantum nature of surface plasmon polaritons
An atomic scale comparison of the reaction of Bioglass® in two types of simulated body fluid
A class of melt quenched silicate glasses, containing calcium, phosphorus and alkali metals, and having the ability to promote bone regeneration and to fuse to living bone, is produced commercially as Bioglass. The changes in structure associated with reacting the bioglass with a body fluid simulant (a buffered Tris(hydroxymethyl)aminomethane growth medium solution or a blood plasma-like salt simulated body fluid) at 37°C have been studied using both high energy and grazing incidence x-ray diffraction. This has corroborated the generic conclusions of earlier studies based on the use of calcia–silica sol-gel glasses whilst highlighting the important differences associated with glass composition; the results also reveal the more subtle effects on reaction rates of the choice of body fluid simulant. The results also indicate the presence of tricalcium phosphate crystallites deposited onto the surface of the glass as a precursor to the growth of hydroxyapatite, and indicates that there is some preferred orientation to their growth
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Effect of elevated CO2 and high temperature on seed-set and grain quality of rice
Hybrid vigour may help overcome the negative effects of climate change in rice. A popular rice hybrid (IR75217H), a heat-tolerant check (N22), and a mega-variety (IR64) were tested for tolerance of seed-set and grain quality to high-temperature stress at anthesis at ambient and elevated [CO2]. Under an ambient air temperature of 29 °C (tissue temperature 28.3 °C), elevated [CO2] increased vegetative and reproductive growth, including seed yield in all three genotypes. Seed-set was reduced by high temperature in all three genotypes, with the hybrid and IR64 equally affected and twice as sensitive as the tolerant cultivar N22. No interaction occurred between temperature and [CO2] for seed-set. The hybrid had significantly more anthesed spikelets at all temperatures than IR64 and at 29 °C this resulted in a large yield advantage. At 35 °C (tissue temperature 32.9 °C) the hybrid had a higher seed yield than IR64 due to the higher spikelet number, but at 38 °C (tissue temperature 34–35 °C) there was no yield advantage. Grain gel consistency in the hybrid and IR64 was reduced by high temperatures only at elevated [CO2], while the percentage of broken grains increased from 10% at 29 °C to 35% at 38 °C in the hybrid. It is concluded that seed-set of hybrids is susceptible to short episodes of high temperature during anthesis, but that at intermediate tissue temperatures of 32.9 °C higher spikelet number (yield potential) of the hybrid can compensate to some extent. If the heat tolerance from N22 or other tolerant donors could be transferred into hybrids, yield could be maintained under the higher temperatures predicted with climate change
The development and characterization of a human mesothelioma in vitro 3D model to investigate immunotoxin therapy.
BackgroundTumor microenvironments present significant barriers to penetration by antibodies and immunoconjugates. Tumor microenvironments, however, are difficult to study in vitro. Cells cultured as monolayers exhibit less resistance to therapy than those grown in vivo and an alternative research model more representative of the in vivo tumor is more desirable. SS1P is an immunotoxin composed of the Fv portion of a mesothelin-specific antibody fused to a bacterial toxin that is presently undergoing clinical trials in mesothelioma.Methodology/principal findingsHere, we examined how the tumor microenvironment affects the penetration and killing activity of SS1P in a new three-dimensional (3D) spheroid model cultured in vitro using the human mesothelioma cell line (NCI-H226) and two primary cell lines isolated from the ascites of malignant mesothelioma patients. Mesothelioma cells grown as monolayers or as spheroids expressed comparable levels of mesothelin; however, spheroids were at least 100 times less affected by SS1P. To understand this disparity in cytotoxicity, we made fluorescence-labeled SS1P molecules and used confocal microscopy to examine the time course of SS1P penetration within spheroids. The penetration was limited after 4 hours. Interestingly, we found a significant increase in the number of tight junctions in the core area of spheroids by electron microscopy. Expression of E-Cadherin, a protein involved in the assembly and sealing of tight junctions and highly expressed in malignant mesothelioma, was found significantly increased in spheroids as compared to monolayers. Moreover, we found that siRNA silencing and antibody inhibition targeting E-Cadherin could enhance SS1P immunotoxin therapy in vitro.Conclusion/significanceThis work is one of the first to investigate immunotoxins in 3D tumor spheroids in vitro. This initial description of an in vitro tumor model may offer a simple and more representative model of in vivo tumors and will allow for further investigations of the microenvironmental effects on drug penetration and tumor cell killing. We believe that the methods developed here may apply to the studies of other tumor-targeting antibodies and immunoconjugates in vitro
Polarized Magnetic Wire Induced by Tunneling Through a Magnetic Impurity
Using the zero mode method we compute the conductance of a wire consisting of
a magnetic impurity coupled to two Luttinger liquid leads characterized by the
Luttinger exponent . We find for resonance conditions, in which
the Fermi energy of the leads is close to a single particle energy of the
impurity, the conductance as a function of temperature is , whereas for off-resonance conditions the conductance is
. By applying a gate voltage and/or
a magnetic field, one of the spin components can be in resonance while the
other is off-resonance causing a strong asymmetry between the spin-up and
spin-down conductances.Comment: 8 pages, submitted to PR
Demonstration of a 1/4 cycle phase shift in the radiation-induced oscillatory-magnetoresistance in GaAs/AlGaAs devices
We examine the phase and the period of the radiation-induced
oscillatory-magnetoresistance in GaAs/AlGaAs devices utilizing in-situ magnetic
field calibration by Electron Spin Resonance of DiPhenyl-Picryl-Hydrazal. The
results confirm a -independent 1/4 cycle phase shift with respect to the condition for , and they also suggest a small
( 2%) reduction in the effective mass ratio, , with respect
to the standard value for GaAs/AlGaAs devices.Comment: 4 pages, 4 color figure
Poboljšanje značajki ekosustava Populus sp. agrošumarskim sustavom gospodarenja
Agroforestry is a multifunctional, environmentally-friendly and modern system of land use by which we can reach economic, environmental and social benefits for the society. This is confirmed by this study on poplar plantations along the Danube River in the region of Vidin (Bulgaria) where agroforestry was practiced by intercropping cultivation of vegetable crops. Productivity of poplars is improving by applying agroforestry. The average diameters and the average heights of trees in the areas with agroforestry are high for the correspondent age. Thus the 10 yеаrs old plantation with agroforestry has DBH = 9.9 cm and Hav = 7.44 m whereas the same aged control has worse dendrometric characteristics (DBH = 8.7 cm ; Hav = 7.04 m). The other sample plot (SP1) near Novo selo village with 2 years old plantation where are currently planted corn has DBH = 2.7 cm and Hav = 2.67 m. The sample plot (SP3) near Vidin with 3 years old plantation where before 1 year has been planted corn has DBH = 1.6 cm and Hav = 2.55 m. The creation of agroforestry systems also leads to improvement of soil properties. Total soil humus content is higher in poplar ecosystems with agroforestry (varied from 4.3% to 2.5%) in comparison with the control (2%). Regarding the composition of organic matter, the control has the smallest content of stable humic acids (0.20%) in comparison with the other three agroforestry systems which have humic acids contents from 0.78% to 0.49%. At the same time control has the highest content of fulvic acids (0.62%) which is more mobile and less stable in comparison with humic acids. The content of fulvic acids in the other plots (with agroforestry) varied from 0.46% to 0.05%. At the same time the control has the highest content of “aggressive” fulvic acids (0.05%). This gives as reason to recommend agroforestry systems as appropriate in growing Populus sp. in Vidin region on Fluvisol.Agrošumarstvo je višenamjenski, okolišno povoljan i moderan sustav korištenja zemljišta kojim se mogu postići ekonomske, okolišne i socijalne dobrobiti za društvo. Ovom studijom se to potvrđuje na primjeru plantaža topola uz rijeku Dunav u regiji Vidin (Bugarska) u koje je uveden i uzgoj povrtlarskih kultura. Primjenom agrošumarskih metoda proizvodnost plantaža topola je povećana. Prosječni prsni promjeri i prosječne visine stabala u područjima u kojima je primijenjeno agrošumarstvo su veći u odnosu na plantaže bez primjene agrošumarstva iste dobi. Desetgodišnja plantaža uz primjenu agrošumarstva ima prosječni prsni promjer stabala od 8,70 cm i prosječnu visinu od 7,44 m, dok kontrolna ploha ima lošije dendrometrijske značajke (prsni promjer od 7,44 cm i prosječnu visinu od 7,04 cm). Uspostava agrošumarskog sustava također je dovela i do poboljšanja značajki tla. Sadržaj humusa u tlu je veći u plantažama s primijenjenim agrošumarskim sustavom (4,3-2,5%) u odnosu na kontrolnu plohu (2%). S obzirom na sastav organske tvari, kontrolna ploha ima najmanji udio huminskih kiselina (stabilni dio organske tvari) (0,20%) u usporedbi s agrošumarskim sustavom (0,78-0,49%). Ujedno, kontrolna površina ima najveći udio fulvo kiselina (mobilni dio organske tvari (0,62%) u usporedbi s agrošumarskim sustavom (0,46-0,05%) i najveći udio “agresivnih” fulvo kiselina (0,05%). Na temelju rezultata ovoga istraživanja, razložno je preporučiti agrošumarski sustav gospodarenja kao odgovarajući za uzgajanje plantaža topola na fluvisolima regije Vidin
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