11,214 research outputs found
Pointing and voicing in deictic expressions
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Land Use Implications of Expanding Biofuel Demand
The Renewable Fuel Standard mandates in the Energy Independence and Security Act of 2007 will require 36 billion gallons of ethanol to be produced in 2022. The mandates require that 16 of the 36 billion gallons must be produced from cellulosic feedstocks. The potential land use implications resulting from these mandates were examined using two methods, the POLYSYS model and a general equilibrium model. Results of the POLYSYS analysis indicated that 72.1 million tons of corn stover, 23.5 million tons of wheat straw, and 24.7 million acres would be used to produce 109 million tons of switchgrass in 2025 to meet the mandate. Results of the CGE analysis indicated that 10.9 billion bushels of corn grain, 71 million tons of corn stover, and 56,200 tons of switchgrass is needed to meet the mandate.cellulosic ethanol, corn stover, grain ethanol, renewable fuel standard, switchgrass, Crop Production/Industries, Demand and Price Analysis, Environmental Economics and Policy, Land Economics/Use, Resource /Energy Economics and Policy, Q15, Q42,
ESTIMATING PRICE VARIABILITY IN AGRICULTURE: IMPLICATIONS FOR DECISION MAKERS
Using a stochastic version of the POLYSYS modeling framework, an examination of projected variability in agricultural prices, supply, demand, stocks, and incomes is conducted for corn, wheat, soybeans, and cotton during the 1998-2006 period. Increased planting flexibility introduced in the 1996 farm bill results in projections of significantly higher planted acreage variability compared to recent historical levels. Variability of ending stocks and stock-to-use ratios is projected to be higher for corn and soybeans and lower for wheat and cotton compared to the 1986-96 period. Significantly higher variability is projected for corn prices, with wheat and soybean prices also being more variable. No significant change in cotton price variability is projected.POLYSYS model, Price variability, Stochastic simulation, Crop Production/Industries,
Black hole scaling relations of active and quiescent galaxies: Addressing selection effects and constraining virial factors
Local samples of quiescent galaxies with dynamically measured black hole
masses (Mbh) may suffer from an angular resolution-related selection effect,
which could bias the observed scaling relations between Mbh and host galaxy
properties away from the intrinsic relations. In particular, previous work has
shown that the observed Mbh-Mstar (stellar mass) relation is more strongly
biased than the Mbh-sigma (velocity dispersion) relation. Local samples of
active galactic nuclei (AGN) do not suffer from this selection effect, as in
these samples Mbh is estimated from megamasers and/or reverberation
mapping-based techniques. With the exception of megamasers, Mbh-estimates in
these AGN samples are proportional to a virial coefficient fvir. Direct
modelling of the broad line region suggests that fvir~3.5. However, this
results in a Mbh-Mstar relation for AGN which lies below and is steeper than
the one observed for quiescent black hole samples. A similar though milder
trend is seen for the Mbh-sigma relation. Matching the high-mass end of the
Mbh-Mstar and Mbh-sigma relations observed in quiescent samples requires
fvir~15 and fvir~7, respectively. On the other hand, fvir~3.5 yields Mbh-sigma
and Mbh-Mstar relations for AGN which are remarkably consistent with the
expected `intrinsic' correlations for quiescent samples (i.e., once account has
been made of the angular resolution-related selection effect), providing
additional evidence that the sample of local quiescent black holes is biased.
We also show that, as is the case for quiescent black holes, the Mbh-Mstar
scaling relation of AGN is driven by velocity dispersion, thus providing
additional key constraints to black hole-galaxy co-evolution models.Comment: 15 pages, 5 Figures. MNRAS, accepte
Statistical relational learning with soft quantifiers
Quantification in statistical relational learning (SRL) is either existential or universal, however humans might be more inclined to express knowledge using soft quantifiers, such as ``most'' and ``a few''. In this paper, we define the syntax and semantics of PSL^Q, a new SRL framework that supports reasoning with soft quantifiers, and present its most probable explanation (MPE) inference algorithm. To the best of our knowledge, PSL^Q is the first SRL framework that combines soft quantifiers with first-order logic rules for modelling uncertain relational data. Our experimental results for link prediction in social trust networks demonstrate that the use of soft quantifiers not only allows for a natural and intuitive formulation of domain knowledge, but also improves the accuracy of inferred results
Injectable laminin-functionalized hydrogel for nucleus pulposus regeneration.
Cell delivery to the pathological intervertebral disc (IVD) has significant therapeutic potential for enhancing IVD regeneration. The development of injectable biomaterials that retain delivered cells, promote cell survival, and maintain or promote an NP cell phenotype in vivo remains a significant challenge. Previous studies have demonstrated NP cell - laminin interactions in the nucleus pulposus (NP) region of the IVD that promote cell attachment and biosynthesis. These findings suggest that incorporating laminin ligands into carriers for cell delivery may be beneficial for promoting NP cell survival and phenotype. Here, an injectable, laminin-111 functionalized poly(ethylene glycol) (PEG-LM111) hydrogel was developed as a biomaterial carrier for cell delivery to the IVD. We evaluated the mechanical properties of the PEG-LM111 hydrogel, and its ability to retain delivered cells in the IVD space. Gelation occurred in approximately 20 min without an initiator, with dynamic shear moduli in the range of 0.9-1.4 kPa. Primary NP cell retention in cultured IVD explants was significantly higher over 14 days when cells were delivered within a PEG-LM111 carrier, as compared to cells in liquid suspension. Together, these results suggest this injectable laminin-functionalized biomaterial may be an easy to use carrier for delivering cells to the IVD
Efficient Bayesian-based Multi-View Deconvolution
Light sheet fluorescence microscopy is able to image large specimen with high
resolution by imaging the sam- ples from multiple angles. Multi-view
deconvolution can significantly improve the resolution and contrast of the
images, but its application has been limited due to the large size of the
datasets. Here we present a Bayesian- based derivation of multi-view
deconvolution that drastically improves the convergence time and provide a fast
implementation utilizing graphics hardware.Comment: 48 pages, 20 figures, 1 table, under review at Nature Method
Automatic memory processes in normal ageing and Alzheimer’s disease
This study examined the contribution of automatic and controlled uses of memory to stem completion in young, middle-aged and older adults, and compared these data with a study involving patients with Alzheimer’s disease (AD) who performed the same task (Hudson and Robertson, 2007). In an inclusion task participants aimed to complete three-letter word stems with a previously studied word, in an exclusion task the aim was to avoid using studied words to complete stems. Performances under inclusion and exclusion conditions were contrasted to obtain estimates of controlled and automatic memory processes using process-dissociation calculations (Jacoby, 1991).
An age-related decline, evident from middle age was observed for the estimate of controlled processing, whereas the estimate of automatic processing remained invariant across the age groups. This pattern stands in contrast to what is observed in AD, where both controlled and automatic processes have been shown to be impaired. Therefore, the impairment in memory processing on stem completion that is found in AD is qualitatively different from that observed in normal ageing
Relative dispersion in fully developed turbulence: The Richardson's Law and Intermittency Corrections
Relative dispersion in fully developed turbulence is investigated by means of
direct numerical simulations. Lagrangian statistics is found to be compatible
with Richardson description although small systematic deviations are found. The
value of the Richardson constant is estimated as , in a close
agreement with recent experimental findings [S. Ott and J. Mann J. Fluid Mech.
{\bf 422}, 207 (2000)]. By means of exit-time statistics it is shown that the
deviations from Richardson's law are a consequence of Eulerian intermittency.
The measured Lagrangian scaling exponents require a set of Eulerian structure
function exponents which are remarkably close to standard ones
known for fully developed turbulence
Integrin-mediated interactions with extracellular matrix proteins for nucleus pulposus cells of the human intervertebral disc.
The extracellular matrix (ECM) of the human intervertebral disc is rich in molecules that interact with cells through integrin-mediated attachments. Porcine nucleus pulposus (NP) cells have been shown to interact with laminin (LM) isoforms LM-111 and LM-511 through select integrins that regulate biosynthesis and cell attachment. Since human NP cells lose many phenotypic characteristics with age, attachment and interaction with the ECM may be altered. Expression of LM-binding integrins was quantified for human NP cells using flow cytometry. The cell-ECM attachment mechanism was determined by quantifying cell attachment to LM-111, LM-511, or type II collagen after functionally blocking specific integrin subunits. Human NP cells express integrins β1, α3, and α5, with over 70% of cells positive for each subunit. Blocking subunit β1 inhibited NP cell attachment to all substrates. Blocking subunits α1, α2, α3, and α5 simultaneously, but not individually, inhibits NP cell attachment to laminins. While integrin α6β1 mediated porcine NP cell attachment to LM-111, we found integrins α3, α5, and β1 instead contributed to human NP cell attachment. These findings identify integrin subunits that may mediate interactions with the ECM for human NP cells and could be used to promote cell attachment, survival, and biosynthesis in cell-based therapeutics
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