2,259 research outputs found
Geodemographic approaches to identifying U.S. furniture markets
Demand for household furniture is shaped by a multitude of dynamic forces, from the global economic situation to subtle changes in consumer preferences. Correspondingly, the academic disciplines employed to identify, analyze, and predict these forces range from macroeconomics to psychology, and include demography, sociology, geography, and several applied fields. The demographic characteristics of furniture consumers has been a particularly popular area of research, primarily because of the availability of secondary data from various public · agencies. Some of this research is reviewed in a subsequent section of this report
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Direct observation of delithiation as the origin of analog memristance in LixNbO2
The discovery of analog LixNbO2 memristors revealed a promising new memristive mechanism wherein the diffusion of Li+ rather than O2- ions enables precise control of the resistive states. However, directly correlating lithium concentration with changes to the electronic structure in active layers remains a challenge and is required to truly understand the underlying physics. Chemically delithiated single crystals of LiNbO2 present a model system for correlating lithium variation with spectroscopic signatures from operando soft x-ray spectroscopy studies of device active layers. Using electronic structure modeling of the x-ray spectroscopy of LixNbO2 single crystals, we demonstrate that the intrinsic memristive behavior in LixNbO2 active layers results from field-induced degenerate p-type doping. We show that electrical operation of LixNbO2-based memristors is viable even at marginal Li deficiency and that the analog memristive switching occurs well before the system is fully metallic. This study serves as a benchmark for material synthesis and characterization of future LixNbO2-based memristor devices and suggests that valence change switching is a scalable alternative that circumvents the electroforming typically required for filamentary-based memristors
Eukaryotic influence on the oceanic biological carbon pump in the Scotia Sea as revealed by 18S rRNA gene sequencing of suspended and sinking particles
Suspended marine particles constitute most of the particulate organic matter pool in the oceans, thereby providing substantial substrates for heterotrophs, especially in the mesopelagic. Conversely, sinking particles are major contributors to carbon fluxes defining the strength of the biological carbon pump (BCP). This study is the first to investigate the differential influence of eukaryotic communities to suspended and sinking particles, using 18S rRNA gene sequencing on particles collected with a marine snow catcher in the mixed layer and upper mesopelagic of the Scotia Sea, Southern Ocean. In the upper mesopelagic, most eukaryotic phytoplankton sequences belonged to chainâforming diatoms in sinking particles and to prymnesiophytes in suspended particles. This suggests that diatomâenriched particles are more efficient in carbon transfer to the upper mesopelagic than those enriched in prymnesiophytes in the Scotia Sea, the latter more easily disintegrating into suspended particles. In the upper mesopelagic, copepods appeared most influential on sinking particles whereas softâtissue metazoan sequences contributed more to suspended particles. Heterotrophic protists and fungi communities were distinct between mixed layer and upper mesopelagic, implying that few protists ride along sinking particles. Furthermore, differences between predatory flagellates and radiolarians between suspended and sinking particles implied different ecological conditions between the two particles pools, and roles in the BCP. Molecular analyses of sinking and suspended particles constitute powerful diagnostic tools to study the eukaryotic influence on the BCP in a more holistic manner compared to classic carbon export studies focusing on sinking particles
Considering Intra-individual Genetic Heterogeneity to Understand Biodiversity
In this chapter, I am concerned with the concept of Intra-individual Genetic Hetereogeneity (IGH) and its potential influence on biodiversity estimates. Definitions of biological individuality are often indirectly dependent on genetic sampling -and vice versa. Genetic sampling typically focuses on a particular locus or set of loci, found in the the mitochondrial, chloroplast or nuclear genome. If ecological function or evolutionary individuality can be defined on the level of multiple divergent genomes, as I shall argue is the case in IGH, our current genetic sampling strategies and analytic approaches may miss out on relevant biodiversity. Now that more and more examples of IGH are available, it is becoming possible to investigate the positive and negative effects of IGH on the functioning and evolution of multicellular individuals more systematically. I consider some examples and argue that studying diversity through the lens of IGH facilitates thinking not in terms of units, but in terms of interactions between biological entities. This, in turn, enables a fresh take on the ecological and evolutionary significance of biological diversity
Preservation of cognitive function in primary CNS lymphoma survivors a median of 12 years after enhanced chemotherapy delivery
Using iron oxide nanoparticles to diagnose CNS inflammatory diseases and PCNSL
Abstract
OBJECTIVE:
The study goal was to assess the benefits and potential limitations in the use of ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles in the MRI diagnosis of CNS inflammatory diseases and primary CNS lymphoma.
METHODS:
Twenty patients with presumptive or known CNS lesions underwent MRI study. Eighteen patients received both gadolinium-based contrast agents (GBCAs) and 1 of 2 USPIO contrast agents (ferumoxytol and ferumoxtran-10) 24 hours apart, which allowed direct comparative analysis. The remaining 2 patients had only USPIO-enhanced MRI because of a renal contraindication to GBCA. Conventional T1- and T2-weighted MRI were acquired before and after contrast administration in all patients, and perfusion MRI for relative cerebral blood volume (rCBV) assessment was obtained in all 9 patients receiving ferumoxytol.
RESULTS:
USPIO-enhanced MRI showed an equal number of enhancing brain lesions in 9 of 18 patients (50%), more enhancing lesions in 2 of 18 patients (11%), and fewer enhancing lesions in 3 of 18 patients (17%) compared with GBCA-enhanced MRI. Four of 18 patients (22%) showed no MRI enhancement. Dynamic susceptibility-weighted contrast-enhanced perfusion MRI using ferumoxytol showed low rCBV (ratio <1.0) in 3 cases of demyelination or inflammation, modestly elevated rCBV in 5 cases of CNS lymphoma or lymphoproliferative disorder (range: 1.3-4.1), and no measurable disease in one case.
CONCLUSIONS:
This study showed that USPIO-enhanced brain MRI can be useful in the diagnosis of CNS inflammatory disorders and lymphoma, and is also useful for patients with renal compromise at risk of nephrogenic systemic fibrosis who are unable to receive GBCA
Impact of local recharge on arsenic concentrations in shallow aquifers inferred from the electromagnetic conductivity of soils in Araihazar, Bangladesh
The high-degree of spatial variability of dissolved As levels in shallow aquifers of the Bengal Basin has been well documented but the underlying mechanisms remain poorly understood. We compare here As concentrations measured in groundwater pumped from 4700 wells <22 m (75 ft) deep across a 25 km2 area of Bangladesh with variations in the nature of surface soils inferred from 18,500 measurements of frequency domain electromagnetic induction. A set of 14 hand auger cores recovered from the same area indicate that a combination of grain size and the conductivity of soil water dominate the electromagnetic signal. The relationship between pairs of individual EM conductivity and dissolved As measurements within a distance of 50 m is significant but highly scattered (r2 = 0.12; n = 614). Concentrations of As tend to be lower in shallow aquifers underlying sandy soils and higher below finer-grained and high conductivity soils. Variations in EM conductivity account for nearly half the variance of the rate of increase of As concentration with depth, however, when the data are averaged over a distance of 50 m (r2 = 0.50; n = 145). The association is interpreted as an indication that groundwater recharge through permeable sandy soils prevents As concentrations from rising in shallow reducing groundwater
Bioinformatic Characterization of Genes and Proteins Involved in Blood Clotting in Lampreys
Lampreys and hagfish are the earliest diverging of extant vertebrates and are obvious targets for investigating the origins of complex biochemical systems found in mammals. Currently, the simplest approach for such inquiries is to search for the presence of relevant genes in whole genome sequence (WGS) assemblies. Unhappily, in the past a high-quality complete genome sequence has not been available for either lampreys or hagfish, precluding the possibility of proving gene absence. Recently, improved but still incomplete genome assemblies for two species of lamprey have been posted, and, taken together with an extensive collection of short sequences in the NCBI trace archive, they have made it possible to make reliable counts for specific gene families. Particularly, a multi-source tactic has been used to study the lamprey blood clotting system with regard to the presence and absence of genes known to occur in higher vertebrates. As was suggested in earlier studies, lampreys lack genes for coagulation factors VIII and IX, both of which are critical for the "intrinsic" clotting system and responsible for hemophilia in humans. On the other hand, they have three each of genes for factors VII and X, participants in the "extrinsic" clotting system. The strategy of using raw trace sequence "reads" together with partial WGS assemblies for lampreys can be used in studies on the early evolution of other biochemical systems in vertebrates
Evolutionary distances in the twilight zone -- a rational kernel approach
Phylogenetic tree reconstruction is traditionally based on multiple sequence
alignments (MSAs) and heavily depends on the validity of this information
bottleneck. With increasing sequence divergence, the quality of MSAs decays
quickly. Alignment-free methods, on the other hand, are based on abstract
string comparisons and avoid potential alignment problems. However, in general
they are not biologically motivated and ignore our knowledge about the
evolution of sequences. Thus, it is still a major open question how to define
an evolutionary distance metric between divergent sequences that makes use of
indel information and known substitution models without the need for a multiple
alignment. Here we propose a new evolutionary distance metric to close this
gap. It uses finite-state transducers to create a biologically motivated
similarity score which models substitutions and indels, and does not depend on
a multiple sequence alignment. The sequence similarity score is defined in
analogy to pairwise alignments and additionally has the positive semi-definite
property. We describe its derivation and show in simulation studies and
real-world examples that it is more accurate in reconstructing phylogenies than
competing methods. The result is a new and accurate way of determining
evolutionary distances in and beyond the twilight zone of sequence alignments
that is suitable for large datasets.Comment: to appear in PLoS ON
Statistical Mechanics of Glass Formation in Molecular Liquids with OTP as an Example
We extend our statistical mechanical theory of the glass transition from
examples consisting of point particles to molecular liquids with internal
degrees of freedom. As before, the fundamental assertion is that super-cooled
liquids are ergodic, although becoming very viscous at lower temperatures, and
are therefore describable in principle by statistical mechanics. The theory is
based on analyzing the local neighborhoods of each molecule, and a statistical
mechanical weight is assigned to every possible local organization. This
results in an approximate theory that is in very good agreement with
simulations regarding both thermodynamical and dynamical properties
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