921 research outputs found
Predit: A temporal predictive framework for scheduling systems
Scheduling can be formalized as a Constraint Satisfaction Problem (CSP). Within this framework activities belonging to a plan are interconnected via temporal constraints that account for slack among them. Temporal representation must include methods for constraints propagation and provide a logic for symbolic and numerical deductions. In this paper we describe a support framework for opportunistic reasoning in constraint directed scheduling. In order to focus the attention of an incremental scheduler on critical problem aspects, some discrete temporal indexes are presented. They are also useful for the prediction of the degree of resources contention. The predictive method expressed through our indexes can be seen as a Knowledge Source for an opportunistic scheduler with a blackboard architecture
Data Dissemination Performance in Large-Scale Sensor Networks
As the use of wireless sensor networks increases, the need for
(energy-)efficient and reliable broadcasting algorithms grows. Ideally, a
broadcasting algorithm should have the ability to quickly disseminate data,
while keeping the number of transmissions low. In this paper we develop a model
describing the message count in large-scale wireless sensor networks. We focus
our attention on the popular Trickle algorithm, which has been proposed as a
suitable communication protocol for code maintenance and propagation in
wireless sensor networks. Besides providing a mathematical analysis of the
algorithm, we propose a generalized version of Trickle, with an additional
parameter defining the length of a listen-only period. This generalization
proves to be useful for optimizing the design and usage of the algorithm. For
single-cell networks we show how the message count increases with the size of
the network and how this depends on the Trickle parameters. Furthermore, we
derive distributions of inter-broadcasting times and investigate their
asymptotic behavior. Our results prove conjectures made in the literature
concerning the effect of a listen-only period. Additionally, we develop an
approximation for the expected number of transmissions in multi-cell networks.
All results are validated by simulations
On the Scalability and Message Count of Trickle-based Broadcasting Schemes
As the use of wireless sensor networks increases, the need for efficient and
reliable broadcasting algorithms grows. Ideally, a broadcasting algorithm
should have the ability to quickly disseminate data, while keeping the number
of transmissions low. In this paper, we analyze the popular Trickle algorithm,
which has been proposed as a suitable communication protocol for code
maintenance and propagation in wireless sensor networks. We show that the
broadcasting process of a network using Trickle can be modeled by a Markov
chain and that this chain falls under a class of Markov chains, closely related
to residual lifetime distributions. It is then shown that this class of Markov
chains admits a stationary distribution of a special form. These results are
used to analyze the Trickle algorithm and its message count. Our results prove
conjectures made in the literature concerning the effect of a listen-only
period. Besides providing a mathematical analysis of the algorithm, we propose
a generalized version of Trickle, with an additional parameter defining the
length of a listen-only period.Comment: arXiv admin note: substantial text overlap with arXiv:1407.603
Conserved Amino Acids in Each Subunit of the Heteroligomeric tRNA m\u3csup\u3e1\u3c/sup\u3eA58 Mtase from \u3cem\u3eSaccharomyces cerevisiae\u3c/em\u3e Contribute to tRNA Binding
In Saccharomyces cerevisiae, a two-subunit methyltransferase (Mtase) encoded by the essential genes TRM6 and TRM61 is responsible for the formation of 1-methyladenosine, a modified nucleoside found at position 58 in tRNA that is critical for the stability of . The crystal structure of the homotetrameric m1A58 tRNA Mtase from Mycobacterium tuberculosis, TrmI, has been solved and was used as a template to build a model of the yeast m1A58 tRNA Mtase heterotetramer. We altered amino acids in TRM6 and TRM61 that were predicted to be important for the stability of the heteroligomer based on this model. Yeast strains expressing trm6 and trm61 mutants exhibited growth phenotypes indicative of reduced m1A formation. In addition, recombinant mutant enzymes had reduced in vitro Mtase activity. We demonstrate that the mutations introduced do not prevent heteroligomer formation and do not disrupt binding of the cofactor S-adenosyl-l-methionine. Instead, amino acid substitutions in either Trm6p or Trm61p destroy the ability of the yeast m1A58 tRNA Mtase to bind , indicating that each subunit contributes to tRNA binding and suggesting a structural alteration of the substrate-binding pocket occurs when these mutations are present
NMR Dynamics Investigation of Ligand-Induced Changes of Main and Side-Chain Arginine N-H’s in Human Phosphomevalonate Kinase
Phosphomevalonate kinase (PMK) catalyzes phosphoryl transfer from adenosine triphosphate (ATP) to mevalonate 5-phosphate (M5P) on the pathway for synthesizing cholesterol and other isoprenoids. To permit this reaction, its substrates must be brought proximal, which would result in a significant and repulsive buildup of negative charge. To facilitate this difficult task, PMK contains 17 arginines and eight lysines. However, the way in which this charge neutralization and binding is achieved, from a structural and dynamics perspective, is not known. More broadly, the role of arginine side-chain dynamics in binding of charged substrates has not been experimentally defined for any protein to date. Herein we report a characterization of changes to the dynamical state of the arginine side chains in PMK due to binding of its highly charged substrates, ATP and M5P. These studies were facilitated by the use of arginine-selective labeling to eliminate spectral overlap. Model-free analysis indicated that while substrate binding has little effect on the arginine backbone dynamics, binding of either substrate leads to significant rigidification of the arginine side chains throughout the protein, even those that are \u3e8 Å from the binding site. Such a global rigidification of arginine side chains is unprecedented and suggests that there are long-range electrostatic interactions of sufficient strength to restrict the motion of arginine side chains on the picosecond-to-nanosecond time scale. It will be interesting to see whether such effects are general for arginine residues in proteins that bind highly charged substrates, once additional studies of arginine side-chain dynamics are reported
Pengaruh Persepsi Pelaksanaan Sensus Pajak Nasional, Pengetahuan dan Pemahaman Peraturan Perpajakan, dan Kesadaran Perpajakan terhadap Kepatuhan Wajib Pajak Orang Pribadi (Wpop) pada Kpp Pratama Pekanbaru Senapelan
The research was conducted to determine the effect of Perception of national tax census, knowledge and understanding of taxation laws, tax awareness, with taxpayers compliance personal. This research conducted on Pekanbaru Senapelan tax services office (KPP). The population in this rearch was all taxpayer listed in Pekanbaru Senapelan tax service office (KPP). This study uses purposive sampling with a sample size of 100 respondent. This research uses primary data questionnaire. This research used quantitative methods with multiple regression analysis models. Partial regression test showed that Perception of national tax census, knowledge and understanding of taxation laws has positive effect to the taxpayer compliance personal and variable tax awarenes has not effect to the taxpayer compliance personal. The magnitude of the effect caused by Adjusted (R2) by three independent variables is 44,3%, while the remaining 55,7% is influenced by other variables not examined in this study.Keywords: Perception, census, knowledge, tax, and complianc
Pengaruh Self Assessment System, Penerbitan Surat Tagihan Pajak dan Penagihan Pajak dengan Surat Paksa terhadap Penerimaan Pajak Pertambahan Nilai pada Kpp Madya dan Kpp Pratama Tampan Pekanbaru
Proceeds from taxation sector is the largest source of state revenue. There are many factors that can affect the amount of tax receipts especially VAT receipts which can be considered the tax general directorate in making a policy. This study aims to examine the effects of the independent variables (PKP registered, SSP VAT, VAT return period reported, STP VAT and SP VAT) on the dependent variable (Value Added Tax receipt) with partial test. The data obtained for this study came from the Tax Service Office Madya Pekanbaru and Tax Service Office Pratama Tampan Pekanbaru, including number registered PKP, the amount deposited by the SSP VAT, the amount of the VAT return period reported by PKP, the amount of STP VAT and SP VAT issued by the tax authorities and the amount of VAT receipts. The method used in this research is descriptive statistical methods. The sampling method using sampling methods saturated, whereas the type of data used are secondary data with monthly data unit for 4 years so it amounted to 48 pieces, once the data is collected, the data were analyzed using SPSS 20.0 for windows. The data were analyzed to test the hypothesis using multiple linear regression analysis approach.. The research results are as follows: (1) The number of registered PKP and CNS VAT effect on VAT receipts. (2) The amount of time the VAT tax return does not affect the VAT receipts. (3) STPs and Forced report VAT has no affect the VAT receipts.The capability of independent variables explain Value Added Tax Receipts of 78,1% and the remaining 21,9% is influenced by other variables
Substrate Induced Structural and Dynamics Changes in Human Phosphomevalonate Iinase and Implications for Mechanism
Phosphomevalonate kinase (PMK) catalyzes an essential step in the mevalonate pathway, which is the only pathway for synthesis of isoprenoids and steroids in humans. PMK catalyzes transfer of the γ-phosphate of ATP to mevalonate 5-phosphate (M5P) to form mevalonate 5-diphosphate. Bringing these phosphate groups in proximity to react is especially challenging, given the high negative charge density on the four phosphate groups in the active site. As such, conformational and dynamics changes needed to form the Michaelis complex are of mechanistic interest. Herein, we report the characterization of substrate induced changes (Mg-ADP, M5P, and the ternary complex) in PMK using NMR-based dynamics and chemical shift perturbation measurements. Mg-ADP and M5P Kd\u27s were 6–60 μM in all complexes, consistent with there being little binding synergy. Binding of M5P causes the PMK structure to compress (τc = 13.5 nsec), whereas subsequent binding of Mg-ADP opens the structure up (τc = 15.6 nsec). The overall complex seems to stay very rigid on the psec-nsec timescale with an average NMR order parameter of S2 ∼0.88. Data are consistent with addition of M5P causing movement around a hinge region to permit domain closure, which would bring the M5P domain close to ATP to permit catalysis. Dynamics data identify potential hinge residues as H55 and R93, based on their low order parameters and their location in extended regions that connect the M5P and ATP domains in the PMK homology model. Likewise, D163 may be a hinge residue for the lid region that is homologous to the adenylate kinase lid, covering the “Walker-A” catalytic loop. Binding of ATP or ADP appears to cause similar conformational changes; however, these observations do not indicate an obvious role for γ-phosphate binding interactions. Indeed, the role of γ-phosphate interactions may be more subtle than suggested by ATP/ADP comparisons, because the conservative O to NH substitution in the β-γ bridge of ATP causes a dramatic decrease in affinity and induces few chemical shift perturbations. In terms of positioning of catalytic residues, binding of M5P induces a rigidification of Gly21 (adjacent to the catalytically important Lys22), although exchange broadening in the ternary complex suggests some motion on a slower timescale does still occur. Finally, the first nine residues of the N-terminus are highly disordered, suggesting that they may be part of a cleavable signal or regulatory peptide sequence. Proteins 2009. © 2008 Wiley-Liss, Inc
Validation of Drug-Like Inhibitors against Mycobacterium Tuberculosis L-Aspartate α-Decarboxylase Using Nuclear Magnetic Resonance (1H NMR)
10.1371/journal.pone.0045947PLoS ONE79
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