3,790 research outputs found
Synthesis, Characterization and Evaluation of Sulphated Zirconias for Biodiesel Production by Triglyceride Cracking
Cold Induction of EARLI1, a Putative Arabidopsis Lipid Transfer Protein, Is Light and Calcium Dependent
As sessile organisms, plants must adapt to their environment. One approach toward understanding this adaptation is to investigate environmental regulation of gene expression. Our focus is on the environmental regulation of EARLI1, which is activated by cold and long-day photoperiods. Cold activation of EARLI1 in short-day photoperiods is slow, requiring several hours at 4ºC to detect an increase in mRNA abundance. EARLI1 is not efficiently cold-activated in etiolated seedlings, suggesting that photomorphogenesis is necessary for its cold activation. Cold activation of EARLI1 is inhibited in the presence of the calcium channel blocker lanthanum chloride or the calcium chelator EGTA. Addition of the calcium ionophore Bay K8644 results in cold-independent activation of EARLI1. These data suggest that EARLI1 is not an immediate target of the cold response, and that calcium flux affects its expression. EARLI1 is a putative secreted protein and has motifs found in lipid transfer proteins. Over-expression of EARLI1 in transgenic plants results in reduced electrolyte leakage during freezing damage, suggesting that EARLI1 may affect membrane or cell wall stability in response to low temperature stress
Petrography and Geochemistry of Metals in Almahata Sitta Ureilites
Ureilites are ultramafic achondrites, predominantly composed of olivine and pyroxenes with accessory carbon, metal and sulfide. The majority of ureilites are believed to represent the mantle of the ureilite parent body (UPB) [1]. Although ureilites have lost much of their original metal [2], the metal that remains retains a record of the formative processes. Almahata Sitta is predominantly composed of unbrecciated ureilites with a wide range of silicate compositions [3,4]. As a fall it presents a rare opportunity to examine fresh ureilite metal in-situ, and analyzing their highly siderophile element (HSE) ratios gives clues to their formation. Bulk siderophile element analyses of Almahata Sitta fall within the range observed in other ureilites [5]. We have examined the metals in seven ureilitic samples of Almahata Sitta (AS) and one associated chondrite fragment (AS#25)
Charge and Current in the Quantum Hall Matrix Model
We extend the quantum Hall matrix model to include couplings to external
electric and magnetic fields. The associated current suffers from matrix
ordering ambiguities even at the classical level. We calculate the linear
response at low momenta -- this is unambigously defined. In particular, we
obtain the correct fractional quantum Hall conductivity, and the expected
density modulations in response to a weak and slowly varying magnetic field.
These results show that the classical quantum Hall matrix models describe
important aspects of the dynamics of electrons in the lowest Landau level. In
the quantum theory the ordering ambiguities are more severe; we discuss
possible strategies, but we have not been able to construct a good density
operator, satisfying the pertinent lowest Landau level commutator algebra.Comment: 12 pages, no figures; a logical error below the proposed density
operator (46) in version 1 is corrected, and the claim that this density
operator satisfy the magnetic algebra (2) is withdrawn. Some formulations
have been changed and a few misprints correcte
Dynamic Bayesian Combination of Multiple Imperfect Classifiers
Classifier combination methods need to make best use of the outputs of
multiple, imperfect classifiers to enable higher accuracy classifications. In
many situations, such as when human decisions need to be combined, the base
decisions can vary enormously in reliability. A Bayesian approach to such
uncertain combination allows us to infer the differences in performance between
individuals and to incorporate any available prior knowledge about their
abilities when training data is sparse. In this paper we explore Bayesian
classifier combination, using the computationally efficient framework of
variational Bayesian inference. We apply the approach to real data from a large
citizen science project, Galaxy Zoo Supernovae, and show that our method far
outperforms other established approaches to imperfect decision combination. We
go on to analyse the putative community structure of the decision makers, based
on their inferred decision making strategies, and show that natural groupings
are formed. Finally we present a dynamic Bayesian classifier combination
approach and investigate the changes in base classifier performance over time.Comment: 35 pages, 12 figure
Novel Mechanisms in Heart Failure With Preserved, Midrange and Reduced Ejection Fraction
Heart failure (HF) represents a major epidemic with high morbidity and mortality rates, imposing a significant burden on healthcare systems worldwide (Savarese and Lund, 2017). HF has long been distinguished by ejection fraction (EF) into two types—HF with reduced ejection fraction (HFrEF), for which EF is below 40%, and HF with preserved ejection fraction (HFpEF), for which EF is above 50% and, according to the 2016 European Society of Cardiology (ESC) Guidelines (Ponikowski et al., 2016), accompanies (1) an elevated level of natriuretic peptides (BNP > 35 pg/ml and/or NT-proBNP > 125 pg/mL) and (2) the presence of either structural heart disease (left ventricular hypertrophy and/or left atrial enlargement) or diastolic dysfunction. HFrEF and HFpEF were initially considered to be binary opposing entities at two ends of the same spectrum. However, whilst several studies have demonstrated the efficacy of drug therapies in improving quality-of-life and long-term clinical outcomes in HFrEF patients, such pharmacological approaches have often failed to yield similar observable benefits in HFpEF cohorts. As such, the current paradigm follows that the pathogenesis underscoring the development and progression of HFrEF and HFpEF are distinct. In more recent developments, the 2016 ESC Guidelines (Ponikowski et al., 2016) also proposed a third class of HF–HF with mid-range ejection fraction (HFmrEF), for which EF is between 40 and 49%, and accompanies the same two aforementioned components of HFpEF. Investigations into this newly defined group of HF patients have yielded contradicting results: whilst some findings have demonstrated an overlap between HFmrEF and the other two classes, others have shown no such association. As a result, a greater understanding of the underlying mechanistic differences between the HF groups, particularly pertaining to HFpEF and HFmrEF, is still needed in order to ensure successful diagnoses and holistic treatment provision. The proposed mechanism for HFrEF is generally well-understood, in which adverse myocardial remodeling, resulting from cardiomyocyte death (Gonzalez et al., 2011) secondary to an inciting stimulus, such as viral myocarditis, myocardial infarction, or drug-induced cardiomyopathy (Bloom et al., 2017), leads to systolic dysfunction (Figure 1A). The same however cannot be said for HFpEF, which is instead associated with a more heterogeneous pathophysiology (Kao et al., 2015). Epidemiological studies have illustrated a comparatively stronger relationship between HFpEF (as opposed to HFrEF) with multiple cardiac and non-cardiac co-morbidities, including but not limited to type 2 diabetes mellitus (T2DM), arterial hypertension, renal failure, obesity, and atrial fibrillation (Elguindy and Yacoub, 2012). This evidently diverse clinical phenotype has elicited much debate regarding the precise mechanisms involved in the development of HFpEF
Competitive Dairy Value Chains in Southeast Asia – Part II : Dairy Expert Roundtable Meeting, December 8 & 9, 2010, Muak Lek, Thailand
The regional Dairy Expert Roundtable Meeting on “Competitive Dairy Value Chains in Southeast Asia” provided a forum for participants from six Southeast Asian countries to discuss how dairy value chains in this region can become more competitive and sustainable. The demand for dairy products in these countries is increasing steadily. Countries rely more and more on imports. Inefficiencies in the chain, low productivity, quality issues, as well as institutional obstacles make locally produced dairy products less competitive. International developments, national policies and experiences, lessons learned, and challenges in the value chain were presented and discussed during the meeting. Many countries in the region face similar challenges. Solutions depend much on the local context. Better exchange of experiences and knowledge among the Southeast Asian countries can contribute to more efficient local dairy value chains. This document, Part II, contains the PowerPoint presentations from the workshop and is an annex to the main report (Part I) of the meeting
User guide for the Biosphere Isotope Domains GB (Version 1) dataset and web portal
This report is a user guide for the Biosphere Isotope Domains GB (V1) dataset, which includes (1) a GIS layer for strontium, sulphur and oxygen isotopes (2) datasets of strontium and sulphur isotope measurements from samples across the Great Britain - published separately and available via BGS and (3) a web portal for viewing and querying the data. A description of the data, methodology and assumptions used in the construction of the Biosphere Isotope Domains GB map is included in the associated publications for strontium (Evans, 2018) and sulphur (Chenery, 2018). The primary application of such datasets is for determining the provenance of skeletal material; although the data may also be of use in modern traceability studies of fauna and flora
Finite-Temperature Transition into a Power-Law Spin Phase with an Extensive Zero-Point Entropy
We introduce an generalization of the frustrated Ising model on a
triangular lattice. The presence of continuous degrees of freedom stabilizes a
{\em finite-temperature} spin state with {\em power-law} discrete spin
correlations and an extensive zero-point entropy. In this phase, the unquenched
degrees of freedom can be described by a fluctuating surface with logarithmic
height correlations. Finite-size Monte Carlo simulations have been used to
characterize the exponents of the transition and the dynamics of the
low-temperature phase
Exclusive processes in position space and the pion distribution amplitude
We suggest to carry out lattice calculations of current correlators in
position space, sandwiched between the vacuum and a hadron state (e.g. pion),
in order to access hadronic light-cone distribution amplitudes (DAs). In this
way the renormalization problem for composite lattice operators is avoided
altogether, and the connection to the DA is done using perturbation theory in
the continuum. As an example, the correlation function of two electromagnetic
currents is calculated to the next-to-next-to-leading order accuracy in
perturbation theory and including the twist-4 corrections. We argue that this
strategy is fully competitive with direct lattice measurements of the moments
of the DA, defined as matrix elements of local operators, and offers new
insight in the space-time picture of hard exclusive reactions.Comment: 15 pages, 10 figure
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