Control Elements (control + element)

Distribution by Scientific Domains


Selected Abstracts


A Modeling Framework for Supply Chain Simulation: Opportunities for Improved Decision Making,

DECISION SCIENCES, Issue 1 2005
D. J. Van Der Zee
ABSTRACT Owing to its inherent modeling flexibility, simulation is often regarded as the proper means for supporting decision making on supply chain design. The ultimate success of supply chain simulation, however, is determined by a combination of the analyst's skills, the chain members' involvement, and the modeling capabilities of the simulation tool. This combination should provide the basis for a realistic simulation model, which is both transparent and complete. The need for transparency is especially strong for supply chains as they involve (semi)autonomous parties each having their own objectives. Mutual trust and model effectiveness are strongly influenced by the degree of completeness of each party's insight into the key decision variables. Ideally, visual interactive simulation models present an important communicative means for realizing the required overview and insight. Unfortunately, most models strongly focus on physical transactions, leaving key decision variables implicit for some or all of the parties involved. This especially applies to control structures, that is, the managers or systems responsible for control, their activities and their mutual attuning of these activities. Control elements are, for example, dispersed over the model, are not visualized, or form part of the time-indexed scheduling of events. In this article, we propose an alternative approach that explicitly addresses the modeling of control structures. First, we will conduct a literature survey with the aim of listing simulation model qualities essential for supporting successful decision making on supply chain design. Next, we use this insight to define an object-oriented modeling framework that facilitates supply chain simulation in a more realistic manner. This framework is meant to contribute to improved decision making in terms of recognizing and understanding opportunities for improved supply chain design. Finally, the use of the framework is illustrated by a case example concerning a supply chain for chilled salads. [source]


Coordinated and conserved expression of alphoid repeat and alphoid repeat-tagged coding sequences

DEVELOPMENTAL DYNAMICS, Issue 1 2003
Yin-Xiong Li
Abstract We have found an alpha-like simple-sequence DNA repeat that is differentially expressed during early embryogenesis in both chick and zebrafish. Before and during the primitive streak stage, transcripts of the alphoid repeat sequence were ubiquitously expressed throughout zebrafish and chick embryos. After headfold formation, expression was limited to the cardiac neural crest, the head, and the heart. Two types of alphoid repeat sequence transcripts were identified: alphoid repeat RNA and alphoid repeat-tagged mRNA (ES,T). Several of the ES,Ts were identified by (1) searching expressed sequence tag databases, (2) arbitrary rapid amplification of cDNA ends (RACE), and (3) screening embryonic cDNA libraries. The alphoid element was located in the 3, untranslated region of one ES,T that was obtained by RACE. The ES,T sequences encoded a variety of different types of proteins, but all were expressed within tissues that were positive for the alphoid repeat RNA. The presence of two types of coordinately expressed alphoid-like repeat transcripts in maternal RNA with subsequent restriction to the head and heart, and the conservation of these features in disparate vertebrate embryos, suggest that the alphoid repeat sequence may serve as a control element in the gene regulation network. Developmental Dynamics 228:72,81, 2003. © 2003 Wiley-Liss, Inc. [source]


IMP1 interacts with poly(A)-binding protein (PABP) and the autoregulatory translational control element of PABP-mRNA through the KH III-IV domain

FEBS JOURNAL, Issue 24 2006
Gopal P. Patel
Repression of poly(A)-binding protein (PABP) mRNA translation involves the formation of a heterotrimeric ribonucleoprotein complex by the binding of PABP, insulin-like growth factor II mRNA binding protein-1 (IMP1) and the unr gene encoded polypeptide (UNR) to the adenine-rich autoregulatory sequence (ARS) located at the 5, untranslated region of the PABP-mRNA. In this report, we have further characterized the interaction between PABP and IMP1 with the ARS at the molecular level. The dissociation constants of PABP and IMP1 for binding to the ARS RNA were determined to be 2.3 nm and 5.9 nm, respectively. Both PABP and IMP1 interact with each other, regardless of the presence of the ARS, through the conserved C-terminal PABP-C and K-homology (KH) III-IV domains, respectively. Interaction of PABP with the ARS requires at least three out of its four RNA-binding domains, whereas KH III-IV domain of IMP1 is necessary and sufficient for binding to the ARS. In addition, the strongest binding site for both PABP and IMP1 on the ARS was determined to be within the 22 nucleotide-long CCCAAAAAAAUUUACAAAAAA sequence located at the 3, end of the ARS. Results of our analysis suggest that both protein·protein and protein·RNA interactions are involved in forming a stable ribonucleoprotein complex at the ARS of PABP mRNA. [source]


Triangular planar array of a pyramidal adaptive antenna for satellite communications at 1.7 GHz

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2009
J. L. Masa-Campos
Abstract Nowadays, satellite communications are basic for the human lifestyle. In this way, a smart, conformal, and multiarray antenna (GEODA) is being developed in order to receive signals from several satellites simultaneously in the 1.7 GHz working band. An adaptive beam system is able to follow the signals from the satellite constellation. The complex structure of the antenna is based in a 3D composition of planar arrays with triangular shape. These arrays are divided into subarrays of three patches (Cells), composing the single control element for the arrays main beam direction management. Fifteen cells (45 radiating elements) compose each triangular array of the GEODA antenna. In this article, a triangular array prototype is implemented and measured. Likewise, an individual characterization of the array components is presented. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2633,2639, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24692 [source]


Analysis of genetic control elements in eukaryotes: Transcriptional activity or nuclear hitchhiking?

BIOESSAYS, Issue 12 2001
Muriel Zohar
A common way to analyse basal and stimulated activity of eukaryotic genetic control elements, such as promoters and enhancers, is to introduce them into cells via DNA vectors containing an easily assayable reporter gene. Activity is then studied by measurement of transiently produced mRNA or reporter protein. In such assays, it is assumed that the variable measured is proportional to the transcriptional activity of the control element under investigation. Here we question the validity of this generally accepted assumption. Specifically, recent observations indicate that control elements, in addition to modulating transgene transcription, can facilitate the nuclear uptake of their carrier plasmids. This process is mediated by transcription factors or other nuclear proteins harbouring nuclear localisation signals, which bind to the control elements in the cytoplasm and transport the DNA into the nucleus through the protein nuclear import machinery. As the number of mRNA transcripts produced for an epi-chromosomally expressed transgene is directly related to its copy number inside the nucleus, such transport activity may lead to substantial overestimation of the transcriptional potency of the control element(s) studied. BioEssays 23:1176,1179, 2001. © 2001 John Wiley & Sons, Inc. [source]


Applying fuzzy logic and genetic algorithms to enhance the efficacy of the PID controller in buffer overflow elimination for better channel response timeliness over the Internet

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 7 2006
Wilfred W. K. Lin
Abstract In this paper two novel intelligent buffer overflow controllers: the fuzzy logic controller (FLC) and the genetic algorithm controller (GAC) are proposed. In the FLC the extant algorithmic PID controller (PIDC) model, which combines the proportional (P), derivative (D) and integral (I) control elements, is augmented with fuzzy logic for higher control precision. The fuzzy logic divides the PIDC control domain into finer control regions. Every region is then defined either by a fuzzy rule or a ,don't care' state. The GAC combines the PIDC model with the genetic algorithm, which manipulates the parametric values of the PIDC as genes in a chromosome. The FLC and GAC operations are based on the objective function . The principle is that the controller should adaptively maintain the safety margin around the chosen reference point (represent by the ,0' of ) at runtime. The preliminary experimental results for the FLC and GAC prototypes indicate that they are both more effective and precise than the PIDC. After repeated timing analyses with the Intel's VTune Performer Analyzer, it was confirmed that the FLC can better support real-time computing than the GAC because of its shorter execution time and faster convergence without any buffer overflow. Copyright © 2005 John Wiley & Sons, Ltd. [source]


Nitric oxide counteracts angiotensin II induced contraction in efferent arterioles in mice

ACTA PHYSIOLOGICA, Issue 4 2004
A. Patzak
Abstract Aim:, Efferent arterioles (Ef) are one of the final control elements in glomerular haemodynamics. The influence of nitric oxide (NO) on Ef remains ambiguous. Methods:, To test the hypothesis that endothelial NO plays an important role in this context, afferent arterioles (Af) and Ef of wild-type mice (WT), and Ef of mice lacking the endothelial NO synthetase [eNOS(,/,)] were perfused. Perfusion was performed in Ef via Af (orthograde) as well as from the distal end of Ef (retrograde), which provides an estimate for the importance of substances derived from the glomerulus. Angiotensin II (Ang II) was added in doses ranging from 10,12 to 10,6 mol L,1 to the bath solution. Results:, Ang II reduced the luminal diameter of Af to 68 ± 7 and in Ef to 55 ± 8% during orthograde, and to 35 ± 6% during retrograde perfusion (10,6 mol L,1 Ang II) in WT. Pre-treatment with NG -Nitro- l -arginine-methylester (l -NAME) (10,4 mol L,1) increased the Ang II sensitivity in retrograde (17 ± 9%) and orthograde perfused Ef (19 ± 9%). The Ang II sensitivity was enhanced in eNOS(,/,) mice compared with WT, too. Already at a dose of Ang II 10,9 mol L,1, luminal diameters diminished to 8 ± 7 and 7 ± 4%. Conclusion:, The increased Ang II sensitivity during l -NAME pre-treatment and in eNOS(,/,) mice indicates a strong counteraction of endothelial derived NO on Ang II induced contraction in Ef. Moreover, Ef are similarly sensitive to Ang II during either retrograde or orthograde perfusion in the absence of NO effects, suggesting that NO mediates, at least in part, the action of potential vasodilatory substances from the glomerulus. [source]


Evaluation of combined gene regulatory elements for transcriptional targeting of suicide gene expression to malignant melanoma

EXPERIMENTAL DERMATOLOGY, Issue 6 2003
Heike Rothfels
Abstract:, Selective killing of tumors can be achieved by targeting the transcription of suicide genes via specific DNA control elements to malignant cells. Three different enhancer-promoter systems were constructed and evaluated for their capability to direct gene expression to melanoma. Two tissue-specific (tyrosinase and MIA) promoters and one weak viral promoter were fused to multiple tandem copies of a melanocyte-specific enhancer element. Reporter gene assays revealed a maximum increase in transcription by combining each promoter with 3,4 copies of the enhancer and demonstrated that all enhancer-promoter combinations exhibited tissue-specific activity. Though this activity was still significantly less than that of the strong but unspecific cytomegalo virus (CMV) promoter. In contrast, when these combinations were employed to drive the expression of two suicide genes, encoding the diphtheria toxin A chain (DT-A) and the prodrug-activating herpes simplex virus thymidine kinase (TK), respectively, only those constructs in which transcription was under the control of tissue-specific promoter elements mediated selective killing of melanoma cells. This killing was in the range of cell death induced by CMV promoter activity. Our data indicate that the enhancer/tyrosinase and enhancer/MIA promoter constructs but not the viral promoter constructs can provide a valuable tool for selective suicide gene expression in melanoma. [source]


A transgenic Cre mouse line for the study of cortical and hippocampal development

GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 5 2010
Wei Zhou
Abstract Wnt signaling regulates cortical and hippocampal development. In a previous study we found that a particular Wnt receptor, Frizzled9 (Fzd9), was selectively expressed in both the developing and adult hippocampus. Taking advantage of the specificity of this promoter, we generated a transgenic cre mouse line using the putative control elements of the Fzd9 gene. In the Fzd9-cre mice, Cre is mainly detected in the developing cortex and hippocampus and is confined to the CA fields and dentate gyrus in adults. Furthermore, by crossing the Fzd9-cre mouse with the ROSA26 reporter line, we examined the activity of Cre and found that it has very high recombination efficiency. Thus, this mouse line will likely prove to be a useful tool for studying cortical and hippocampal development via activation or inactivation of interesting genes. genesis 48:343,350, 2010. © 2010 Wiley-Liss, Inc. [source]


An Anopheles gambiae salivary gland promoter analysis in Drosophila melanogaster and Anopheles stephensi

INSECT MOLECULAR BIOLOGY, Issue 2 2005
F. Lombardo
Abstract Regulatory regions driving gene expression in specific target organs of the African malaria vector Anopheles gambiae are of critical relevance for studies on Plasmodium,Anopheles interactions as well as to devise strategies for blocking malaria parasite development in the mosquito. In order to identify an appropriate salivary gland promoter we analysed the transactivation properties of genomic fragments located just upstream of the An. gambiae female salivary gland-specific genes AgApy and D7r4. An 800 bp fragment from the AgApy gene directed specific expression of the LacZ reporter gene in the salivary glands of transgenic Anopheles stephensi. However, expression levels were lower than expected and the transgene was expressed in the proximal-rather than in the distal-lateral lobes of female glands. Surprisingly, a promoter fragment from the D7r4 gene conferred strong tissue-specific expression in Drosophila melanogaster but only low transcription levels in transgenic An. stephensi. These results imply a certain conservation of gland-specific control elements between the fruit fly and the mosquito suggesting that an increased degree of complexity, probably connected to the evolution of haematophagy, underlies the regulation of tissue-specific expression in mosquito female salivary glands. [source]


Transcriptional regulation of the human TIMP-1 gene: mapping control elements in intron-1

INTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 1 2000
Greg Dean
[source]


Modular changes of cis-regulatory elements from two functional Pit1 genes in the duplicated genome of Cyprinus carpio

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2006
G. Kausel
Abstract The pituitary-specific transcription factor Pit1 is involved in its own regulation and in a network of transcriptional regulation of hypothalamo-hypophyseal factors including prolactin (PRL) and growth hormone (GH). In the ectotherm teleost Cyprinus carpio, Pit1 plays an important role in regulation of the adaptive response to seasonal environmental changes. Two Pit1 genes exist in carp, a tetraploid vertebrate and transcripts of both genes were detected by RT-PCR analysis. Powerful comparative analyses of the 5,-flanking regions revealed copy specific changes comprising modular functional units in the naturally evolved promoters. These include the precise replacement of four nucleotides around the transcription start site embedded in completely conserved regions extending upstream of the TATA-box, an additional transcription factor binding site in the 5,-UTR of gene-I and, instead, duplication of a 9 bp element in gene-II. Binding of nuclear factors was assessed by electro mobility shift assays using extracts from rat pituitary cells and carp pituitary. Binding was confirmed at one conserved Pit1, one conserved CREB and one consensus MTF1. Interestingly, two functional Pit1 sites and one putative MTF1 binding site are unique to the Pit1 gene-I. In situ hybridization experiments revealed that the expression of gene-I in winter carp was significantly stronger than that of gene-II. Our data suggest that the specific control elements identified in the proximal regulatory region are physiologically relevant for the function of the duplicated Pit1 genes in carp and highlight modular changes in the architecture of two Pit1 genes that evolved for at least 12 MYA in the same organism. J. Cell. Biochem. 99: 905,921, 2006. © 2006 Wiley-Liss, Inc. [source]


Improved controllability test for dependent siphons in S3PR based on elementary siphons

ASIAN JOURNAL OF CONTROL, Issue 3 2010
Daniel Y. Chao
Abstract When siphons in a flexible manufacturing system (FMS) modeled by an ordinary Petri net (OPN) become unmarked, the net gets deadlocked. To prevent deadlocks, some control places and related arcs are added to strict minimal siphons (SMS) so that no siphon can be emptied. For large systems, it is infeasible to add a monitor to every SMS since the number of SMS or control elements grows exponentially with respect to the size of a Petri net. To tackle this problem, Li and Zhou propose to add control nodes and arcs for only elementary siphons. The rest of siphons, called dependent ones, may be controlled by adjusting control depth variables of elementary siphons associated with a dependent siphon after the failure of two tests. First, they test a Marking Linear Inequality (MLI); if it fails, then they perform a Linear Integer Programming (LIP) test which is an NP-hard problem. This implies that the MLI test is only sufficient, but not necessary. We propose a sufficient and necessary test for adjusting control depth variables in an S3PR to avoid the sufficient-only time-consuming linear integer programming (LIP) test (NP-complete problem) required previously for some cases. We theoretically prove the following: i) no need for LIP test for Type II siphons; and ii) Type I strongly n-dependent (n>2) siphons being always marked. As a result, the total time complexity to check controllability of all strongly dependent siphons is no longer exponential but reduced to linear if all siphons are of Type I. The total time complexity is O(|,E||,D|) (order of the product of total number of elementary siphons and total number of dependent siphons) if all siphons are of Type II. A well-known S3PR example has been illustrated to show the advantages. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]


Analysis of genetic control elements in eukaryotes: Transcriptional activity or nuclear hitchhiking?

BIOESSAYS, Issue 12 2001
Muriel Zohar
A common way to analyse basal and stimulated activity of eukaryotic genetic control elements, such as promoters and enhancers, is to introduce them into cells via DNA vectors containing an easily assayable reporter gene. Activity is then studied by measurement of transiently produced mRNA or reporter protein. In such assays, it is assumed that the variable measured is proportional to the transcriptional activity of the control element under investigation. Here we question the validity of this generally accepted assumption. Specifically, recent observations indicate that control elements, in addition to modulating transgene transcription, can facilitate the nuclear uptake of their carrier plasmids. This process is mediated by transcription factors or other nuclear proteins harbouring nuclear localisation signals, which bind to the control elements in the cytoplasm and transport the DNA into the nucleus through the protein nuclear import machinery. As the number of mRNA transcripts produced for an epi-chromosomally expressed transgene is directly related to its copy number inside the nucleus, such transport activity may lead to substantial overestimation of the transcriptional potency of the control element(s) studied. BioEssays 23:1176,1179, 2001. © 2001 John Wiley & Sons, Inc. [source]