28,123 research outputs found
Sac1p mediates the adenosine triphosphate transport into yeast endoplasmic reticulum that is required for protein translocation.
Protein translocation into the yeast endoplasmic reticulum requires the transport of ATP into the lumen of this organelle. Microsomal ATP transport activity was reconstituted into proteoliposomes to characterize and identify the transporter protein. A polypeptide was purified whose partial amino acid sequence demonstrated its identity to the product of the SAC1 gene. Accordingly, microsomal membranes isolated from strains harboring a deletion in the SAC1 gene (sac1 delta) were found to be deficient in ATP-transporting activity as well as severely compromised in their ability to translocate nascent prepro-alpha-factor and preprocarboxypeptidase Y. Proteins isolated from the microsomal membranes of a sac1 delta strain were incapable of stimulating ATP transport when reconstituted into the in vitro assay system. When immunopurified to homogeneity and incorporated into artificial lipid vesicles, Sac1p was shown to reconstitute ATP transport activity. Consistent with the requirement for ATP in the lumen of the ER to achieve the correct folding of secretory proteins, the sac1 delta strain was shown to have a severe defect in transport of procarboxypeptidase Y out of the ER and into the Golgi complex in vivo. The collective data indicate an intimate role for Sac1p in the transport of ATP into the ER lumen
Conformal Toda theory with a boundary
We investigate sl(n) conformal Toda theory with maximally symmetric
boundaries. There are two types of maximally symmetric boundary conditions, due
to the existence of an order two automorphism of the W(n>2) algebra. In one of
the two cases, we find that there exist D-branes of all possible dimensions 0
=< d =< n-1, which correspond to partly degenerate representations of the W(n)
algebra. We perform classical and conformal bootstrap analyses of such
D-branes, and relate these two approaches by using the semi-classical light
asymptotic limit. In particular we determine the bulk one-point functions. We
observe remarkably severe divergences in the annulus partition functions, and
attribute their origin to the existence of infinite multiplicities in the
fusion of representations of the W(n>2) algebra. We also comment on the issue
of the existence of a boundary action, using the calculus of constrained
functional forms, and derive the generating function of the B"acklund
transformation for sl(3) Toda classical mechanics, using the minisuperspace
limit of the bulk one-point function.Comment: 42 pages; version 4: added clarifications in section 2.2 and
footnotes 1 and
Gravitational physics with antimatter
The production of low-energy antimatter provides unique opportunities to
search for new physics in an unexplored regime. Testing gravitational
interactions with antimatter is one such opportunity. Here a scenario based on
Lorentz and CPT violation in the Standard- Model Extension is considered in
which anomalous gravitational effects in antimatter could arise.Comment: 5 pages, presented at the International Conference on Exotic Atoms
(EXA 2008) and the 9th International Conference on Low Energy Antiproton
Physics (LEAP 2008), Vienna, Austria, September 200
The Role of the Second Law of Thermodynamics in Continuum Physics: A Muschik and Ehrentraut Theorem Revisited
In continuum physics, constitutive equations model the material properties of physical systems. In those equations, material symmetry is taken into account by applying suitable representation theorems for symmetric and/or isotropic functions. Such mathematical representations must be in accordance with the second law of thermodynamics, which imposes that, in any thermodynamic process, the entropy production must be nonnegative. This requirement is fulfilled by assigning the constitutive equations in a form that guaranties that second law of thermodynamics is satisfied along arbitrary processes. Such an approach, in practice regards the second law of thermodynamics as a restriction on the constitutive equations, which must guarantee that any solution of the balance laws also satisfy the entropy inequality. This is a useful operative assumption, but not a consequence of general physical laws. Indeed, a different point of view, which regards the second law of thermodynamics as a restriction on the thermodynamic processes, i.e., on the solutions of the system of balance laws, is possible. This is tantamount to assuming that there are solutions of the balance laws that satisfy the entropy inequality, and solutions that do not satisfy it. In order to decide what is the correct approach, Muschik and Ehrentraut in 1996, postulated an amendment to the second law, which makes explicit the evident (but rather hidden) assumption that, in any point of the body, the entropy production is zero if, and only if, this point is a thermodynamic equilibrium. Then they proved that, given the amendment, the second law of thermodynamics is necessarily a restriction on the constitutive equations and not on the thermodynamic processes. In the present paper, we revisit their proof, lighting up some geometric aspects that were hidden in therein. Moreover, we propose an alternative formulation of the second law of thermodynamics, which incorporates the amendment. In this way we make this important result more intuitive and easily accessible to a wider audience
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Deep Neural Network Cloud-Type Classification (DeepCTC) model and its application in evaluating PERSIANN-CCS
Satellite remote sensing plays a pivotal role in characterizing hydrometeorological components including cloud types and their associated precipitation. The Cloud Profiling Radar (CPR) on the Polar Orbiting CloudSat satellite has provided a unique dataset to characterize cloud types. However, data from this nadir-looking radar offers limited capability for estimating precipitation because of the narrow satellite swath coverage and low temporal frequency. We use these high-quality observations to build a Deep Neural Network Cloud-Type Classification (DeepCTC) model to estimate cloud types from multispectral data from the Advanced Baseline Imager (ABI) onboard the GOES-16 platform. The DeepCTC model is trained and tested using coincident data from both CloudSat and ABI over the CONUS region. Evaluations of DeepCTC indicate that the model performs well for a variety of cloud types including Altostratus, Altocumulus, Cumulus, Nimbostratus, Deep Convective and High clouds. However, capturing low-level clouds remains a challenge for the model. Results from simulated GOES-16 ABI imageries of the Hurricane Harvey event show a large-scale perspective of the rapid and consistent cloud-type monitoring is possible using the DeepCTC model. Additionally, assessments using half-hourly Multi-Radar/Multi-Sensor (MRMS) precipitation rate data (for Hurricane Harvey as a case study) show the ability of DeepCTC in identifying rainy clouds, including Deep Convective and Nimbostratus and their precipitation potential. We also use DeepCTC to evaluate the performance of the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Cloud Classification System (PERSIANN-CCS) product over different cloud types with respect to MRMS referenced at a half-hourly time scale for July 2018. Our analysis suggests that DeepCTC provides supplementary insights into the variability of cloud types to diagnose the weakness and strength of near real-time GEO-based precipitation retrievals. With additional training and testing, we believe DeepCTC has the potential to augment the widely used PERSIANN-CCS algorithm for estimating precipitation
Performance and Comparative Analysis of the Two Contrary Approaches for Detecting Near Duplicate Web Documents in Web Crawling
Recent years have witnessed the drastic development of World Wide Web (WWW). Information is being accessible at the finger tip anytime anywhere through the massive web repository. The performance and reliability of web engines thus face huge problems due to the presence of enormous amount of web data. The voluminous amount of web documents has resulted in problems for search engines leading to the fact that the search results are of less relevance to the user. In addition to this, the presence of duplicate and near-duplicate web documents has created an additional overhead for the search engines critically affecting their performance. The demand for integrating data from heterogeneous sources leads to the problem of near-duplicate web pages. The detection of near duplicate documents within a collection has recently become an area of great interest. In this research, we have presented an efficient approach for the detection of near duplicate web pages in web crawling which uses keywords and the distance measure. Besides that, G.S. Manku et al.’s fingerprint based approach proposed in 2007 was considered as one of the “state-of-the-art" algorithms for finding near-duplicate web pages. Then we have implemented both the approaches and conducted an extensive comparative study between our similarity score based approach and G.S. Manku et al.’s fingerprint based approach. We have analyzed our results in terms of time complexity, space complexity, Memory usage and the confusion matrix parameters. After taking into account the above mentioned performance factors for the two approaches, the comparison study clearly portrays our approach the better (less complex) of the two based on the factors considered.DOI:http://dx.doi.org/10.11591/ijece.v2i6.1746
Gauge Theory Wilson Loops and Conformal Toda Field Theory
The partition function of a family of four dimensional N=2 gauge theories has
been recently related to correlation functions of two dimensional conformal
Toda field theories. For SU(2) gauge theories, the associated two dimensional
theory is A_1 conformal Toda field theory, i.e. Liouville theory. For this case
the relation has been extended showing that the expectation value of gauge
theory loop operators can be reproduced in Liouville theory inserting in the
correlators the monodromy of chiral degenerate fields. In this paper we study
Wilson loops in SU(N) gauge theories in the fundamental and anti-fundamental
representation of the gauge group and show that they are associated to
monodromies of a certain chiral degenerate operator of A_{N-1} Toda field
theory. The orientation of the curve along which the monodromy is evaluated
selects between fundamental and anti-fundamental representation. The analysis
is performed using properties of the monodromy group of the generalized
hypergeometric equation, the differential equation satisfied by a class of four
point functions relevant for our computation.Comment: 17 pages, 3 figures; references added
Atomic transition frequencies, isotope shifts, and sensitivity to variation of the fine structure constant for studies of quasar absorption spectra
Theories unifying gravity with other interactions suggest spatial and
temporal variation of fundamental "constants" in the Universe. A change in the
fine structure constant, alpha, could be detected via shifts in the frequencies
of atomic transitions in quasar absorption systems. Recent studies using 140
absorption systems from the Keck telescope and 153 from the Very Large
Telescope, suggest that alpha varies spatially. That is, in one direction on
the sky alpha seems to have been smaller at the time of absorption, while in
the opposite direction it seems to have been larger.
To continue this study we need accurate laboratory measurements of atomic
transition frequencies. The aim of this paper is to provide a compilation of
transitions of importance to the search for alpha variation. They are E1
transitions to the ground state in several different atoms and ions, with
wavelengths ranging from around 900 - 6000 A, and require an accuracy of better
than 10^{-4} A. We discuss isotope shift measurements that are needed in order
to resolve systematic effects in the study. The coefficients of sensitivity to
alpha-variation (q) are also presented.Comment: Includes updated version of the "alpha line" lis
Effect of Terminalia chebula fruit extract on lipid peroxidation and antioxidative system of testis of albino rats
The effect of aqueous extract of the Terminalia chebula was studied in male albino rats to explore its activities on testis. 1.0 ml of aqueous extract of T. chebula (500 mg/kg body weight) was given orally for 45 days. The activity of lipid peroxidation and superoxide dismutase were significantly increased but the concentration of antioxidant enzyme glutathione, and catalase were decreased in the aqueous extract administered rats rather than in control rats. Significant decrease in the activities of antioxidant enzymes, spermatogenesis and increase in the level of lipid peroxidation, indicate the severity of oxidative stress induced as a result of administration of extract of T. chebula. The aqueous extract also lead to changes in the parameters such as sperm count, motility and morphology, protein and cholesterol content of the rat testis. The long term (45 days) administration of the extract causes significant changes in the rat testis
't Hooft Operators in Gauge Theory from Toda CFT
We construct loop operators in two dimensional Toda CFT and calculate with
them the exact expectation value of certain supersymmetric 't Hooft and dyonic
loop operators in four dimensional \Ncal=2 gauge theories with SU(N) gauge
group. Explicit formulae for 't Hooft and dyonic operators in \Ncal=2^* and
\Ncal=2 conformal SQCD with SU(N) gauge group are presented. We also briefly
speculate on the Toda CFT realization of arbitrary loop operators in these
gauge theories in terms of topological web operators in Toda CFT.Comment: 49 pages, LaTeX. Typos fixed, references adde
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