514 research outputs found
Treasury inflation-indexed debt: a review of the U.S. experience
This article describes the evolution of Treasury inflation-indexed debt securities (TIIS) since their introduction in 1997. Over most of this period, TIIS yields have been surprisingly high relative to those on comparable nominal Treasury securities, with the spread between the nominal and indexed yields falling well below survey measures of long-run inflation expectations. The authors argue that the low relative valuation of TIIS may have reflected investor difficulty adjusting to a new asset class, supply trends, and the lower liquidity of indexed debt. In addition, investors may have had a benign outlook for inflation and may not have demanded much, if any, of an inflation risk premium to hold nominal securities. As a result, inflation-indexed debt has not yet lived up to one of its main purposes: to reduce the Treasury's expected financing costs. More recently, though, TIIS market liquidity and the breadth of investor participation have increased considerably, and the valuation of these securities appears to have improved.Inflation-indexed bonds ; Treasury bonds ; Treasury notes ; Rate of return
El lugar y su relación con los recientes debates interdisciplinarios
Cet article expose les problbmes relatifs au lieu en tant qu'un concept intégrateur en géographie et dans un champ interdisciplinaire plus large. On montre que l'expérience du lieu est universelle et constitue un aspect élémentaire de la vie, que les différences entre les sciences sociales, les humanités et les sciences naturelles ont morcellé cette expérience, que la culture moderne (spécialement celle de consommation de masse) approfondit ce morcellement lors qu'elle essaie d'offrir une solution, et, finalement, qu'une conception unificatrice du lieu constitue un pont essentiel entre les humanités et les sciences sociales et naturelles.This essay discusses the problems involving place as an intergrating concept within geography and within a larger interdisciplinary arena. It shows that the experience of place is a universal and elemental part of life; that differences among social science, humanities and natural science have segmented this experience, that modem culture -especially mass consumption- reinforces this segmentation while attempting to offer a solution; and that a unified conception of place is an essential bridge among the humanities, social and natural sciences.Este articulo presenta los problemas entomo al lugar como concepto integrador en la geografia y en una arena interdisciplinaris mas amplia. Muestra que la experiencia del lugar es una parte universal y elemental de la vida; que las diferencia~ entre ciencias sociales, humanidades y ciencias naturales han segmentado esta experiencia, y que la cultura moderna, especialmente el consumo de masas, refuerza esta fragmentacion mientras intenta ofrecer una solucion; finalmente, el articulo muestra que una concepción unificada del lugar es un puente esencial entre las humanidades, las ciencias sociales y las ciencias naturales.Aquest article presenta els problemes entorn del lloc com a concepte integrador dins de la geografia i dins d'un context interdisciplinari més ampli. Mostra que l'experiència del lloc és una part universal i elemental de la vida; que les diferencies entre ciències socials, humanitats i ciències naturals han fragmentat aquesta experiència, i que la cultura moderna, especialment la del consum de masses, ha reforçat aquesta segmentació mentre intenta oferir una solució; finalment, l'article mostra que una concepció unificada del lloc és un pont essencial entre les humanitats, les ciències socials i les ciències naturals
Influence of a magnetic field on the viscosity of a dilute gas consisting of linear molecules.
The viscomagnetic effect for two linear molecules, N2 and CO2, has been calculated in the dilute-gas limit directly from the most accurate ab initio intermolecular potential energy surfaces presently available. The calculations were performed by means of the classical trajectory method in the temperature range from 70 K to 3000 K for N2 and 100 K to 2000 K for CO2, and agreement with the available experimental data is exceptionally good. Above room temperature, where no experimental data are available, the calculations provide the first quantitative information on the magnitude and the behavior of the viscomagnetic effect for these gases. In the presence of a magnetic field, the viscosities of nitrogen and carbon dioxide decrease by at most 0.3% and 0.7%, respectively. The results demonstrate that the viscomagnetic effect is dominated by the contribution of the jj¯ polarization at all temperatures, which shows that the alignment of the rotational axes of the molecules in the presence of a magnetic field is primarily responsible for the viscomagnetic effect
Reconversion of Parahydrogen Gas in Surfactant-Coated Glass NMR Tubes
The application of parahydrogen gas to enhance the magnetic resonance signals of a diversity of chemical species has increased substantially in the last decade. Parahydrogen is prepared by lowering the temperature of hydrogen gas in the presence of a catalyst; this enriches the para spin isomer beyond its normal abundance of 25% at thermal equilibrium. Indeed, parahydrogen fractions that approach unity can be attained at sufficiently low temperatures. Once enriched, the gas will revert to its normal isomeric ratio over the course of hours or days, depending on the surface chemistry of the storage container. Although parahydrogen enjoys long lifetimes when stored in aluminum cylinders, the reconversion rate is significantly faster in glass containers due to the prevalence of paramagnetic impurities that are present within the glass. This accelerated reconversion is especially relevant for nuclear magnetic resonance (NMR) applications due to the use of glass sample tubes. The work presented here investigates how the parahydrogen reconversion rate is affected by surfactant coatings on the inside surface of valved borosilicate glass NMR sample tubes. Raman spectroscopy was used to monitor changes to the ratio of the (J: 0 → 2) vs. (J: 1 → 3) transitions that are indicative of the para and ortho spin isomers, respectively. Nine different silane and siloxane-based surfactants of varying size and branching structures were examined, and most increased the parahydrogen reconversion time by 1.5×–2× compared with equivalent sample tubes that were not treated with surfactant. This includes expanding the pH2 reconversion time from 280 min in a control sample to 625 min when the same tube is coated with (3-Glycidoxypropyl)trimethoxysilane
Structure determination of PF3 adsorption on Cu(100) using X-ray standing waves
The local structure of the Cu(100)c(4x2)-PF3 adsorption phase has been investigated through the use of normal-incidence X-ray standing waves (NIXSW), monitored by P 1s and F 1s photoemission, together with P K-edge near-edge X-ray absorption fine structure (NEXAFS). NEXAFS shows the molecule to be oriented with its C3v symmetry axis essentially perpendicular to the surface, while the P NIXSW data show the molecule to be adsorbed in atop sites 2.37±0.04 Å above the surface, this distance corresponding to the Cu-P nearest-neighbour distance in the absence of any surface relaxation. F NIXSW indicates a surprisingly small height difference of the P and F atoms above the surface 0.44±0.06 Å, compared with the value expected for an undistorted gas-phase geometry of 0.77 Å, implying significant increases in the F-P-F bond angles. In addition, however, the F NIXSW data indicate that the molecules have a well-defined azimuthal orientation with a molecular mirror plane aligned in a substrate mirror plane, and with a small (5-10°) tilt of the molecule in this plane such that the two symmetrically-equivalent F atoms in each molecule are tilted down towards the surface
Resolving Australian analogs for an Eocene Patagonian paleorainforest using leaf size and floristics
• Premise of the study: The diverse early Eocene flora from Laguna del Hunco (LH) in Patagonia, Argentina has many nearest living relatives (NLRs) in Australasia but few in South America, indicating the differential survival of an ancient, trans‐Antarctic rainforest biome. To better understand this significant biogeographic pattern, we used detailed comparisons of leaf size and floristics to quantify the legacy of LH across a large network of Australian rainforest‐plot assemblages. • Methods: We applied vein scaling, a new method for estimating the original areas of fragmented leaves. We then compared leaf size and floristics at LH with living Australian assemblages and tabulated the climates of those where NLRs occur, along with additional data on climatic ranges of “ex‐Australian” NLRs that survive outside of Australia. • Key results: Vein scaling estimated areas as accurately as leaf‐size classes. Applying vein scaling to fossil fragments increased the grand mean area of LH by 450 mm2, recovering more originally large leaves. The paleoflora has a majority of microphyll leaves, comparable to leaf litter in subtropical Australian forests, which also have the greatest floristic similarity to LH. Tropical Australian assemblages also share many taxa with LH, and ex‐Australian NLRs mostly inhabit cool, wet montane habitats no longer present in Australia. • Conclusions: Vein scaling is valuable for improving the resolution of fossil leaf‐size distributions by including fragmented specimens. The legacy of LH is evident not only in subtropical and tropical Australia but also in tropical montane Australasia and Southeast Asia, reflecting the disparate histories of surviving Gondwanan lineages.Fil: Merkhofer, Lisa. State University of Pennsylvania; Estados UnidosFil: Wilf, Peter. State University of Pennsylvania; Estados UnidosFil: Haas, M. Tyler. State University of Pennsylvania; Estados UnidosFil: Kooyman, Robert M.. Macquarie University; AustraliaFil: Sack, Lawren. University of California at Los Angeles; Estados UnidosFil: Scoffoni, Christine. University of California at Los Angeles; Estados UnidosFil: Cúneo, Néstor Rubén. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Mycobacterium tuberculosis Affects Protein and Lipid Content of Circulating Exosomes in Infected Patients Depending on Tuberculosis Disease State
Tuberculosis (TB), which is caused by the bacterium Mycobacterium tuberculosis (Mtb), is
still one of the deadliest infectious diseases. Understanding how the host and pathogen interact
in active TB will have a significant impact on global TB control efforts. Exosomes are increasingly
recognized as a means of cell-to-cell contact and exchange of soluble mediators. In the case of TB,
exosomes are released from the bacillus and infected cells. In the present study, a comprehensive
lipidomics and proteomics analysis of size exclusion chromatography-isolated plasma-derived exosomes from patients with TB lymphadenitis (TBL) and treated as well as untreated pulmonary TB
(PTB) was performed to elucidate the possibility to utilize exosomes in diagnostics and knowledge
building. According to our findings, exosome-derived lipids and proteins originate from both the
host and Mtb in the plasma of active TB patients. Exosomes from all patients are mostly composed of
sphingomyelins (SM), phosphatidylcholines, phosphatidylinositols, free fatty acids, triacylglycerols
(TAG), and cholesterylesters. Relative proportions of, e.g., SMs and TAGs, vary depending on the
disease or treatment state and could be linked to Mtb pathogenesis and dormancy. We identified
three proteins of Mtb origin: DNA-directed RNA polymerase subunit beta (RpoC), Diacyglycerol
O-acyltransferase (Rv2285), and Formate hydrogenase (HycE), the latter of which was discovered to
be differently expressed in TBL patients. Furthermore, we discovered that Mtb infection alters the
host protein composition of circulating exosomes, significantly affecting a total of 37 proteins. All TB
patients had low levels of apolipoproteins, as well as the antibacterial proteins cathelicidin, Scavenger
Receptor Cysteine Rich Family Member (SSC5D), and Ficolin 3 (FCN3). When compared to healthy
controls, the protein profiles of PTB and TBL were substantially linked, with 14 proteins being coregulated. However, adhesion proteins (integrins, Intercellular adhesion molecule 2 (ICAM2), CD151,
Proteoglycan 4 (PRG4)) were shown to be more prevalent in PTB patients, while immunoglobulins,
Complement component 1r (C1R), and Glutamate receptor-interacting protein 1 (GRIP1) were found
to be more abundant in TBL patients, respectively. This study could confirm findings from previous
reports and uncover novel molecular profiles not previously in focus of TB research. However, we
applied a minimally invasive sampling and analysis of circulating exosomes in TB patients. Based on the findings given here, future studies into host–pathogen interactions could pave the way for the
development of new vaccines and therapies
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