5,530 research outputs found
Optimizing robotic exoskeletons actuation based on human neuromechanics experiments: interaction of push-off timing and work
Do international factors influence the passage of climate change legislation?
The number of climate change laws in major economies has grown from less than 40 in 1997 to almost 500 at the end of 2013. The passage of these laws is influenced by both domestic and international factors. This paper reviews the main international factors, drawing on a powerful new dataset of climate legislation in 66 national jurisdictions. We find that the propensity to legislate on climate change is heavily influenced by the passage of similar laws elsewhere, suggesting a strong and so far under-appreciated role for international policy diffusion. International treaties like the Kyoto Protocol work in two ways. The impact of the Kyoto Protocol itself is limited to countries with formal obligations under the treaty. In addition, the prestige of hosting an international climate summit is associated with a subsequent boost in legislation. Legislators seem to respond to the expectations of climate leadership that these events bestow on their host. Policy relevance: A global solution to climate change will ultimately have to be anchored in domestic legislation, which creates the legal basis for countries to take action. Countries are passing climate legislation in a growing number. This paper asks to what extent they are motivated to do so by international factors, such as existing treaty obligations. We find that the Kyoto Protocol has been a less important factor in explaining climate legislation outside Annex 1 than the passage of similar laws elsewhere. This suggests that international policy diffusion plays an important and so far under-appreciated role in global climate policy, complementing formal treaty obligations
The four-loop beta-function in Quantum Chromodynamics
We present the analytical calculation of the four-loop QCD beta-function
within the minimal subtraction scheme.Comment: 9 pages, Latex, 1 figure, uses axodraw.st
Evolution of the Bianchi I, the Bianchi III and the Kantowski-Sachs Universe: Isotropization and Inflation
We study the Einstein-Klein-Gordon equations for a convex positive potential
in a Bianchi I, a Bianchi III and a Kantowski-Sachs universe. After analysing
the inherent properties of the system of differential equations, the study of
the asymptotic behaviors of the solutions and their stability is done for an
exponential potential. The results are compared with those of Burd and Barrow.
In contrast with their results, we show that for the BI case isotropy can be
reached without inflation and we find new critical points which lead to new
exact solutions. On the other hand we recover the result of Burd and Barrow
that if inflation occurs then isotropy is always reached. The numerical
integration is also done and all the asymptotical behaviors are confirmed.Comment: 22 pages, 12 figures, Self-consistent Latex2e File. To be published
in Phys. Rev.
Two-loop anomalous dimension in light-cone gauge with Mandelstam-Leibbrandt prescription
All the next-to-leading order results on Altarelli-Parisi splitting functions
have been obtained in the literature either by using the operator product
expansion method or by making use of the Curci Furmanski Petronzio (CFP)
formalism in conjunction with light-like axial gauge, principal value (PV)
prescription and dimensional regularization. In this paper we present the
calculation of some non-singlet two-loop anomalous dimensions within the CFP
formalism using light-cone axial gauge with Mandelstam-Leibbrandt (ML)
prescription. We make a detailed comparison between the intermediate results
given by the (PV) versus the (ML) method. We point out that the (ML) method is
completely consistent and avoids the ``phenomenological rules'' used in the
case of (PV) regularization.Comment: 31 pages, LaTe
Release of cell wall phenolic esters during hydrothermal pretreatment of rice husk and rice straw
Background: Rice husk and rice straw represent promising sources of biomass for production of renewable fuels and chemicals. For efficient utilisation, lignocellulosic components must first be pretreated to enable efficient enzymatic saccharification and subsequent fermentation. Existing pretreatments create breakdown products such as sugar-derived furans, and lignin-derived phenolics that inhibit enzymes and fermenting organisms. Alkali pretreatments have also been shown to release significant levels of simple, free phenolics such as ferulic acid that are normally esterified to cell wall polysaccharides in the intact plant. These phenolics have recently been found to have considerable inhibitory properties. The aim of this research has been to establish the extent to which such free phenolic acids are also released during hydrothermal pretreatment of rice straw (RS) and rice husk (RH). Results: RS and RH were subjected to hydrothermal pretreatments over a wide range of severities (1.57–5.45). FTIR analysis showed that the pretreatments hydrolysed and solubilised hemicellulosic moieties, leading to an enrichment of lignin and crystalline cellulose in the insoluble residue. The residues also lost the capacity for UV autofluorescence at pH 7 or pH 10, indicating the breakdown or release of cell wall phenolics. Saponification of raw RS and RH enabled identification and quantification of substantial levels of simple phenolics including ferulic acid (tFA), coumaric acid (pCA) and several diferulic acids (DiFAs) including 8-O-4′-DiFA, 8,5′-DiFA and 5,5′-DiFA. RH had higher levels of pCA and lower levels of tFA and DiFAs compared with RS. Assessment of the pretreatment liquors revealed that pretreatment-liberated phenolics present were not free but remained as phenolic esters (at mM concentrations) that could be readily freed by saponification. Many were lost, presumably through degradation, at the higher severities. Conclusion: Differences in lignin, tFA, DiFAs and pCA between RS and RH reflect differences in cell wall physiology, and probably contribute to the higher recalcitrance of RH compared with RS. Hydrothermal pretreatments, unlike alkali pretreatments, release cinnamic acid components as esters. The potential for pretreatment-liberated phenolic esters to be inhibitory to fermenting microorganisms is not known. However, the present study shows that they are found at concentrations that could be significantly inhibitory if released as free forms by enzyme activity
Characterisation of lignocellulosic sugars from municipal solid waste residue.
Municipal solid waste (MSW) contains significant quantities of plant-derived carbohydrates which have the potential to be exploited as a biomass source. This study evaluated the chemical composition and fractionation of MSW water-insoluble organic matter remaining after recycling of other components (MSWR). The organic matter was prepared as a dry, alcohol insoluble residue (MSWR-AIR, comprising w = 6% of original MSW) and size fractionated into fractions A, B, C & D. Carbohydrates were present in all the sub-fractions, comprising up to w = 54%; their complexity was also assessed by FT-IR spectroscopy. The lignin content in the samples ranged from w = 11–22%. The most carbohydrate-rich subfraction (C; w = 4% original MSW) was sequentially extracted to provide information on the likely constituent cell wall-derived polymers, sugar compositions and uronic acid content. The results indicate that approximately w = 25% of the MSWR-AIR comprises glucose, which appears to be mostly cellulosic in origin. The results are discussed in relation to the potential for exploitation
A review of the microbiological problems and biofilms associated with Mycobacterium chimaera in heater cooler units used for cardiopulmonary bypass
total cross-section in the dipole picture of BFKL dynamics
The total cross-section is derived in the Leading Order
QCD dipole picture of BFKL dynamics, and compared with the one from 2-gluon
exchange. The Double Leading Logarithm approximation of the DGLAP cross-section
is found to be small in the phase space studied. Cross sections are calculated
for realistic data samples at the collider LEP and a future high
energy linear collider. Next to Leading order corrections to the BFKL evolution
have been determined phenomenologically, and are found to give very large
corrections to the BFKL cross-section, leading to a reduced sensitivity for
observing BFKL.Comment: 24 pages, 4 figure
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