3,531 research outputs found
Gauge Symmetries and Renormalization
The preservation of gauge symmetries to the quantum level induces symmetries between renormalized Green's functions. These symmetries are known by the names of Ward-Takahashi and Slavnov-Taylor identities. On a perturbative level, these symmetries can be implemented as Hopf ideals in the Connes-Kreimer renormalization Hopf algebra. In this article, we generalize the existing literature to the most general case by first motivating these symmetries on a generic level and then proving that they indeed generate Hopf ideals, where we also include the more involved cases of super- and non-renormalizable local QFTs. Finally, we provide a criterion for their validity on the level of renormalized Feynman rules
Residual Stresses in Layered Manufacturing
Layered Manufacturing processes accumulate residual stresses during materialbuildup. These stresses may cause part warping and layer delamination. This paper presents
work done on investigating residual stress accumulation andp(i,rt distortion of Layered
Manufactured artifacts. A simple analyticaLmodel was developed and used to determine how the number of layers and the layer thickness influences part warping. Resllits
show that thin layers produce lower part deflection as compared with depositing fewer
and thicker layers. In addition to the analytical work, a finite element model wasdeveloped and used to illvestigate the deposition pattern's influence on. the part deflection.
Finite element model and corresponding experimental analysis showed that the geometry of the deposition pattern significantly affects the resulting part distortion. This
finite element model was also used to investigate an inter-layer surface defect,. known
as the Christmas Thee Step, that is associated with Shape Deposition Manufacturing.
Results indicate that the features of this defect are influenced only by the material
deposited close. to the part·surface and the particular material deposited. The step is
not affected by the deposition pattern.Mechanical Engineerin
Spectral rate theory for projected two-state kinetics
Classical rate theories often fail in cases where the observable(s) or order
parameter(s) used are poor reaction coordinates or the observed signal is
deteriorated by noise, such that no clear separation between reactants and
products is possible. Here, we present a general spectral two-state rate theory
for ergodic dynamical systems in thermal equilibrium that explicitly takes into
account how the system is observed. The theory allows the systematic estimation
errors made by standard rate theories to be understood and quantified. We also
elucidate the connection of spectral rate theory with the popular Markov state
modeling (MSM) approach for molecular simulation studies. An optimal rate
estimator is formulated that gives robust and unbiased results even for poor
reaction coordinates and can be applied to both computer simulations and
single-molecule experiments. No definition of a dividing surface is required.
Another result of the theory is a model-free definition of the reaction
coordinate quality (RCQ). The RCQ can be bounded from below by the directly
computable observation quality (OQ), thus providing a measure allowing the RCQ
to be optimized by tuning the experimental setup. Additionally, the respective
partial probability distributions can be obtained for the reactant and product
states along the observed order parameter, even when these strongly overlap.
The effects of both filtering (averaging) and uncorrelated noise are also
examined. The approach is demonstrated on numerical examples and experimental
single-molecule force probe data of the p5ab RNA hairpin and the apo-myoglobin
protein at low pH, here focusing on the case of two-state kinetics
Contributor and Victim - Indonesia's Role in Global Climate Change with Special Reference to Kalimantan
Through rapid deforestation, forest fires, degrading peatlands, and diminishing carbon ‘sinks' Indonesia is one of the main contributors to the phenomenon of Global Climate Change. On the other hand, Indonesia will also be a major victim of Climate Change. The combination of high population density on some islands and high levels of biodiversity, together with 80,000 kilometres of coastline and 17,500 islands, makes Indonesia one of the most vulnerable countries to the impacts of Climate Change. Experts expect a warming from 0.2 to 0.3°C per decade in Indonesia during this century, together with an increase in annual precipitation across the majority of the Indonesian islands. Additionally there will be a change in the seasonality of precipitation; Borneo may become 10 to 30% wetter by the 2080's during December-February. As rainfall decreases during critical times of the year this translates into higher drought risk, consequently a decrease in crop yields, economic instability and drastically more undernourished people. On the other hand, increased rainfall during already wet times of the year will lead to high flood risk. Rising sea levels and many more extreme weather events will contribute to the many problems caused by Global Climate Change. Indonesia, and Kalimantan in the first instance, has to take up the challenge of climate change in taking actions at all levels to reduce greenhouse gas emissions, including promoting sustainable use of land and water resources, and putting adaptation into the development agenda
Best practice guidelines on logistics and quality assurance for pellet production
http://www.forestenergy.org/observe
"Give Me a Word": A Spiritual Director's Journey with Photography
Utilizing photography in spiritual direction
Action comprehension: deriving spatial and functional relations.
A perceived action can be understood only when information about the action carried out and the objects used are taken into account. It was investigated how spatial and functional information contributes to establishing these relations. Participants observed static frames showing a hand wielding an instrument and a potential target object of the action. The 2 elements could either match or mismatch, spatially or functionally. Participants were required to judge only 1 of the 2 relations while ignoring the other. Both irrelevant spatial and functional mismatches affected judgments of the relevant relation. Moreover, the functional relation provided a context for the judgment of the spatial relation but not vice versa. The results are discussed in respect to recent accounts of action understanding
Polarized Magnetic Wire Induced by Tunneling Through a Magnetic Impurity
Using the zero mode method we compute the conductance of a wire consisting of
a magnetic impurity coupled to two Luttinger liquid leads characterized by the
Luttinger exponent . We find for resonance conditions, in which
the Fermi energy of the leads is close to a single particle energy of the
impurity, the conductance as a function of temperature is , whereas for off-resonance conditions the conductance is
. By applying a gate voltage and/or
a magnetic field, one of the spin components can be in resonance while the
other is off-resonance causing a strong asymmetry between the spin-up and
spin-down conductances.Comment: 8 pages, submitted to PR
Ltc1 is an ER-localized sterol transporter and a component of ER-mitochondria and ER-vacuole contacts.
Organelle contact sites perform fundamental functions in cells, including lipid and ion homeostasis, membrane dynamics, and signaling. Using a forward proteomics approach in yeast, we identified new ER-mitochondria and ER-vacuole contacts specified by an uncharacterized protein, Ylr072w. Ylr072w is a conserved protein with GRAM and VASt domains that selectively transports sterols and is thus termed Ltc1, for Lipid transfer at contact site 1. Ltc1 localized to ER-mitochondria and ER-vacuole contacts via the mitochondrial import receptors Tom70/71 and the vacuolar protein Vac8, respectively. At mitochondria, Ltc1 was required for cell viability in the absence of Mdm34, a subunit of the ER-mitochondria encounter structure. At vacuoles, Ltc1 was required for sterol-enriched membrane domain formation in response to stress. Increasing the proportion of Ltc1 at vacuoles was sufficient to induce sterol-enriched vacuolar domains without stress. Thus, our data support a model in which Ltc1 is a sterol-dependent regulator of organelle and cellular homeostasis via its dual localization to ER-mitochondria and ER-vacuole contact sites
Quantum Dot as Spin Filter and Spin Memory
We consider a quantum dot in the Coulomb blockade regime weakly coupled to
current leads and show that in the presence of a magnetic field the dot acts as
an efficient spin-filter (at the single-spin level) which produces a
spin-polarized current. Conversely, if the leads are fully spin-polarized the
up or down state of the spin on the dot results in a large sequential or small
cotunneling current, and thus, together with ESR techniques, the setup can be
operated as a single-spin memory.Comment: 4 pages, 3 figures, REVTe
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