910 resultados para Theory of the mature cause
Resumo:
There are fibers in the left ventricle (LV) (LV middle network) that in around one third of cases may be considered a true septal fascicle that arises from the common left bundle. Its presence and the evidence that there are 3 points of activation onset in the LV favor the quadrifascicular theory of the intravantricular activation of both ventricles. Since the 70s, different authors have suggested that the block of the left middle fibers (MS)/left septal fascicle may explain different electrocardiographic (ECG) patterns. The 2 hypothetically based criteria that are in some sense contradictory include: a) the lack of septal "q" wave due to first left and later posteriorly shifting of the horizontal plane loop and b) the presence of RS in lead V-2 (V-1-V-2) due to some anterior shifting of the horizontal plane vectorcardiogram loop. However, there are many evidence that the lack of septal q waves can be also explained by predivisional first-degree left bundle-branch block and that the RS pattern in the right precordial leads may be also explained by first-degree right bundle-branch block. The transient nature of these patterns favor the concept that some type of intraventricular conduction disturbance exists but a doubt remains about its location. Furthermore, the RS pattern could be explained by many different normal variants. To improve our understanding whether these patterns are due to MF/left septal fascicle block or other ventricular conduction disturbances (or both), it would be advisable: 1) To perform more histologic studies (heart transplant and necropsy) of the ventricular conduction system; 2) To repeat prior experimental studies using new methodology/technology to isolate the MF; and 3) To change the paradigm: do not try to demonstrate if the block of the fibers produces an ECG change but to study with new electroanatomical imaging techniques, if these ECG criteria previously described correlate or not with a delay of activation in the zone of the LV that receives the activation through these fibers or in other zones. (C) 2012 Elsevier Inc. All rights reserved.
Resumo:
This Doctoral Thesis focuses on the study of individual behaviours as a result of organizational affiliation. The objective is to assess the Entrepreneurial Orientation of individuals proving the existence of a set of antecedents to that measure returning a structural model of its micro-foundation. Relying on the developed measurement model, I address the issue whether some Entrepreneurs experience different behaviours as a result of their academic affiliation, comparing a sample of ‘Academic Entrepreneurs’ to a control sample of ‘Private Entrepreneurs’ affiliated to a matched sample of Academic Spin-offs and Private Start-ups. Building on the Theory of the Planned Behaviour, proposed by Ajzen (1991), I present a model of causal antecedents of Entrepreneurial Orientation on constructs extensively used and validated, both from a theoretical and empirical perspective, in sociological and psychological studies. I focus my investigation on five major domains: (a) Situationally Specific Motivation, (b) Personal Traits and Characteristics, (c) Individual Skills, (d) Perception of the Business Environment and (e) Entrepreneurial Orientation Related Dimensions. I rely on a sample of 200 Entrepreneurs, affiliated to a matched sample of 72 Academic Spin-offs and Private Start-ups. Firms are matched by Industry, Year of Establishment and Localization and they are all located in the Emilia Romagna region, in northern Italy. I’ve gathered data by face to face interviews and used a Structural Equation Modeling technique (Lisrel 8.80, Joreskog, K., & Sorbom, D. 2006) to perform the empirical analysis. The results show that Entrepreneurial Orientation is a multi-dimensional micro-founded construct which can be better represented by a Second-Order Model. The t-tests on the latent means reveal that the Academic Entrepreneurs differ in terms of: Risk taking, Passion, Procedural and Organizational Skills, Perception of the Government, Context and University Supports. The Structural models also reveal that the main differences between the two groups lay in the predicting power of Technical Skills, Perceived Context Support and Perceived University Support in explaining the Entrepreneurial Orientation Related Dimensions.
Resumo:
Die vorliegende Arbeit widmet sich der Spektraltheorie von Differentialoperatoren auf metrischen Graphen und von indefiniten Differentialoperatoren auf beschränkten Gebieten. Sie besteht aus zwei Teilen. Im Ersten werden endliche, nicht notwendigerweise kompakte, metrische Graphen und die Hilberträume von quadratintegrierbaren Funktionen auf diesen betrachtet. Alle quasi-m-akkretiven Laplaceoperatoren auf solchen Graphen werden charakterisiert, und Abschätzungen an die negativen Eigenwerte selbstadjungierter Laplaceoperatoren werden hergeleitet. Weiterhin wird die Wohlgestelltheit eines gemischten Diffusions- und Transportproblems auf kompakten Graphen durch die Anwendung von Halbgruppenmethoden untersucht. Eine Verallgemeinerung des indefiniten Operators $-tfrac{d}{dx}sgn(x)tfrac{d}{dx}$ von Intervallen auf metrische Graphen wird eingeführt. Die Spektral- und Streutheorie der selbstadjungierten Realisierungen wird detailliert besprochen. Im zweiten Teil der Arbeit werden Operatoren untersucht, die mit indefiniten Formen der Art $langlegrad v, A(cdot)grad urangle$ mit $u,vin H_0^1(Omega)subset L^2(Omega)$ und $OmegasubsetR^d$ beschränkt, assoziiert sind. Das Eigenwertverhalten entspricht in Dimension $d=1$ einer verallgemeinerten Weylschen Asymptotik und für $dgeq 2$ werden Abschätzungen an die Eigenwerte bewiesen. Die Frage, wann indefinite Formmethoden für Dimensionen $dgeq 2$ anwendbar sind, bleibt offen und wird diskutiert.
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In this thesis the measurement of the effective weak mixing angle wma in proton-proton collisions is described. The results are extracted from the forward-backward asymmetry (AFB) in electron-positron final states at the ATLAS experiment at the LHC. The AFB is defined upon the distribution of the polar angle between the incoming quark and outgoing lepton. The signal process used in this study is the reaction pp to zgamma + X to ee + X taking a total integrated luminosity of 4.8\,fb^(-1) of data into account. The data was recorded at a proton-proton center-of-mass energy of sqrt(s)=7TeV. The weak mixing angle is a central parameter of the electroweak theory of the Standard Model (SM) and relates the neutral current interactions of electromagnetism and weak force. The higher order corrections on wma are related to other SM parameters like the mass of the Higgs boson.rnrnBecause of the symmetric initial state constellation of colliding protons, there is no favoured forward or backward direction in the experimental setup. The reference axis used in the definition of the polar angle is therefore chosen with respect to the longitudinal boost of the electron-positron final state. This leads to events with low absolute rapidity have a higher chance of being assigned to the opposite direction of the reference axis. This effect called dilution is reduced when events at higher rapidities are used. It can be studied including electrons and positrons in the forward regions of the ATLAS calorimeters. Electrons and positrons are further referred to as electrons. To include the electrons from the forward region, the energy calibration for the forward calorimeters had to be redone. This calibration is performed by inter-calibrating the forward electron energy scale using pairs of a central and a forward electron and the previously derived central electron energy calibration. The uncertainty is shown to be dominated by the systematic variations.rnrnThe extraction of wma is performed using chi^2 tests, comparing the measured distribution of AFB in data to a set of template distributions with varied values of wma. The templates are built in a forward folding technique using modified generator level samples and the official fully simulated signal sample with full detector simulation and particle reconstruction and identification. The analysis is performed in two different channels: pairs of central electrons or one central and one forward electron. The results of the two channels are in good agreement and are the first measurements of wma at the Z resonance using electron final states at proton-proton collisions at sqrt(s)=7TeV. The precision of the measurement is already systematically limited mostly by the uncertainties resulting from the knowledge of the parton distribution functions (PDF) and the systematic uncertainties of the energy calibration.rnrnThe extracted results of wma are combined and yield a value of wma_comb = 0.2288 +- 0.0004 (stat.) +- 0.0009 (syst.) = 0.2288 +- 0.0010 (tot.). The measurements are compared to the results of previous measurements at the Z boson resonance. The deviation with respect to the combined result provided by the LEP and SLC experiments is up to 2.7 standard deviations.
Resumo:
Pesiqta Rabbati is a unique homiletic midrash that follows the liturgical calendar in its presentation of homilies for festivals and special Sabbaths. This article attempts to utilize Pesiqta Rabbati in order to present a global theory of the literary production of rabbinic/homiletic literature. In respect to Pesiqta Rabbati it explores such areas as dating, textual witnesses, integrative apocalyptic meta-narrative, describing and mapping the structure of the text, internal and external constraints that impacted upon the text, text linguistic analysis, form-analysis: problems in the texts and linguistic gap-filling, transmission of text, strict formalization of a homiletic unit, deconstructing and reconstructing homiletic midrashim based upon form-analytic units of the homily, Neusner’s documentary hypothesis, surface structures of the homiletic unit, and textual variants. The suggested methodology may assist scholars in their production of editions of midrashic works by eliminating superfluous material and in their decoding and defining of ancient texts.
Resumo:
My project in this paper is to provide a plausible idea of Christ’s suffering and death in terms of a theory of the human person. More specifically, I want to contrast two major theories of the person-body relation. One is dualism. Dualism is the view that a human person is composed of two substances, that is, a soul and a body, and he (strictly speaking) is identical with the soul. On the other hand, physicalism is the view that a human person is numerically identical with his biological body. I will argue that dualism is not successful in explaining Christ’s passion for some reasons. Rather, physicalism, as I shall argue, provides a better explanation of how Christ’s physical suffering and death are real just like everyone else’s, so it is philosophically and theologically more plausible than dualism.
Resumo:
The NMR structures of the recombinant 217-residue polypeptide chain of the mature bovine prion protein, bPrP(23–230), and a C-terminal fragment, bPrP(121–230), include a globular domain extending from residue 125 to residue 227, a short flexible chain end of residues 228–230, and an N-terminal flexibly disordered “tail” comprising 108 residues for the intact protein and 4 residues for bPrP(121–230), respectively. The globular domain contains three α-helices comprising the residues 144–154, 173–194, and 200–226, and a short antiparallel β-sheet comprising the residues 128–131 and 161–164. The best-defined parts of the globular domain are the central portions of the helices 2 and 3, which are linked by the only disulfide bond in bPrP. Significantly increased disorder and mobility is observed for helix 1, the loop 166–172 leading from the β-strand 2 to helix 2, the end of helix 2 and the following loop, and the last turn of helix 3. Although there are characteristic local differences relative to the conformations of the murine and Syrian hamster prion proteins, the bPrP structure is essentially identical to that of the human prion protein. On the other hand, there are differences between bovine and human PrP in the surface distribution of electrostatic charges, which then appears to be the principal structural feature of the “healthy” PrP form that might affect the stringency of the species barrier for transmission of prion diseases between humans and cattle.
Resumo:
Previous studies have demonstrated that presecretory proteins such as maltose binding protein (MBP) and outer membrane protein A (OmpA) are targeted to the Escherichia coli inner membrane by the molecular chaperone SecB, but that integral membrane proteins are targeted by the signal recognition particle (SRP). In vitro studies have suggested that trigger factor binds to a sequence near the N terminus of the mature region of OmpA and shunts the protein into the SecB pathway by blocking an interaction between SRP and the signal peptide. By contrast, we have found that the targeting pathway of a protein under physiological conditions is dictated by the composition of its targeting signal. Replacement of the MBP or OmpA signal peptide with the first transmembrane segment of AcrB abolished the dependence on SecB for transport and rerouted both proteins into the SRP targeting pathway. More modest alterations of the MBP signal peptide that simply increase its hydrophobicity also promoted SRP binding. Furthermore, we obtained evidence that SRP has a low affinity for typical signal peptides in vivo. These results imply that different classes of E. coli proteins are targeted by distinct pathways because bacterial SRP binds to a more restricted range of targeting signals than its eukaryotic counterpart.
Resumo:
A theory of the unzipping of double-stranded DNA is presented and is compared to recent micromanipulation experiments. It is shown that the interactions that stabilize the double helix and the elastic rigidity of single strands simply determine the sequence-dependent ≈12-pN force threshold for DNA strand separation. Using a semimicroscopic model of the binding between nucleotide strands, we show that the greater rigidity of the strands when formed into double-stranded DNA, relative to that of isolated strands, gives rise to a potential barrier to unzipping. The effects of this barrier are derived analytically. The force to keep the extremities of the molecule at a fixed distance, the kinetic rates for strand unpairing at fixed applied force, and the rupture force as a function of loading rate are calculated. The dependence of the kinetics and of the rupture force on molecule length is also analyzed.
Resumo:
After birth, most of insulin-like growth factor I and II (IGFs) circulate as a ternary complex formed by the association of IGF binding protein 3-IGF complexes with a serum protein called acid-labile subunit (ALS). ALS retains the IGF binding protein-3-IGF complexes in the vascular compartment and extends the t1/2 of IGFs in the circulation. Synthesis of ALS occurs mainly in liver after birth and is stimulated by growth hormone. To study the basis for this regulation, we cloned and characterized the mouse ALS gene. Comparison of genomic and cDNA sequences indicated that the gene is composed of two exons separated by a 1126-bp intron. Exon 1 encodes the first 5 amino acids of the signal peptide and contributes the first nucleotide of codon 6. Exon 2 contributes the last 2 nt of codon 6 and encodes the remaining 17 amino acids of the signal peptide as well as the 580 amino acids of the mature protein. The polyadenylylation signal, ATTAAA, is located 241 bp from the termination codon. The cDNA and genomic DNA diverge 16 bp downstream from this signal. Transcription initiation was mapped to 11 sites over a 140-bp TATA-less region. The DNA fragment extending from nt -805 to -11 (ATG, +1) directed basal and growth hormone-regulated expression of a luciferase reporter plasmid in the rat liver cell line H4-II-E. Finally, the ALS gene was mapped to mouse chromosome 17 by fluorescence in situ hybridization.
Resumo:
The nucleotide sequence of the human alpha-albumin gene, including 887 bp of the 5'-flanking region and 1311 bp of the 3-flanking region (24,454 in total), was determined from three overlapping lambda phage clones. The sequence spans 22,256 bp from the cap site to the polyadenylylation site, revealing a gene structure of 15 exons separated by 14 introns. The methionine initiation codon ATG is within exon 1; the termination codon TGA is within exon 14. Exon 15 is entirely untranslated and contains the polyadenylylation signal AATAAA. The deduced polypeptide chain is composed of a 21-amino-acid leader peptide, followed by 578 amino acids of the mature protein. There are seven repetitive DNA elements (Alu and Kpn) in the introns and 3-flanking region. The sizes of the 15 alpha-albumin exons match closely those of the albumin, alpha-fetoprotein, and vitamin D-binding protein genes. The exons are symmetrically placed within the three domains of the individual proteins, and they share a characteristic codon splitting pattern that is conserved among members of the gene family. The results provide strong evidence that alpha-albumin belongs to, and most likely completes with, the serum albumin gene family. Based on structural similarity, alpha-albumin appears to be most closely related to alpha-fetoprotein. The complete structure of this family of four tandemly linked genes provides a well-characterized approximately 200 kb locus in the 4q subcentromeric region of the human genome.
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An autotrophic theory of the origin of metabolism and life has been proposed in which carbon dioxide is reduced by ferrous sulfide and hydrogen sulfide by means of a reversed citric acid cycle, leading to the production of amino acids. Similar processes have been proposed for purine synthesis. Ferrous sulfide is a strong reducing agent in the presence of hydrogen sulfide and can produce hydrogen as well as reduce alkenes, alkynes, and thiols to saturated hydrocarbons and reduce ketones to thiols. However, the reduction of carbon dioxide has not been demonstrated. We show here that no amino acids, purines, or pyrimidines are produced from carbon dioxide with the ferrous sulfide and hydrogen sulfide system. Furthermore, this system does not produce amino acids from carboxylic acids by reductive amination and carboxylation. Thus, the proposed autotrophic theory, using carbon dioxide, ferrous sulfide, and hydrogen sulfide, lacks the robustness needed to be a geological process and is, therefore, unlikely to have played a role in the origin of metabolism or the origin of life.
Resumo:
The IFNAR chain of the type I interferon (IFN) receptor (IFNIR) undergoes rapid ligand-dependent tyrosine phosphorylation and acts as a species-specific transducer for type I IFN action. Using the vaccinia/T7 expression system to amplify IFNAR expression, we found that human HeLa-S3 cells transiently express high levels of cell surface IFNAR chains (approximately 250,000 chains per cell). Metabolic labeling and immunoblot analysis of transfected HeLa cells show that the IFNAR chain is initially detected as 65-kDa and 98-kDa precursors, and then as the 130-kDa mature protein. Due to variation in N-glycosylation, the apparent molecular mass of the mature IFNAR chain varies from 105 to 135 kDa in different cells. IFNIR structure was characterized in various human cell lines by analyzing 125I-labeled IFN cross-linked complexes recognized by various antibodies against IFNIR subunits and JAK protein-tyrosine kinases. Precipitation of cross-linked material from Daudi cells with anti-IFNAR antibodies showed that IFNAR was present in a 240-kDa complex. Precipitation of cross-linked material from U937 cells with anti-TYK2 sera revealed a 240-kDa complex, which apparently did not contain IFNAR and was not present in IFN-resistant HEC1B cells. The tyrosine phosphorylation and down-regulation of the IFNAR chain were induced by type I IFN in several human cell lines of diverse origins but not in HEC1B cells. However, of type I IFNs, IFN-beta uniquely induced the tyrosine phosphorylation of a 105-kDa protein associated with the IFNAR chain in two lymphoblastoid cell lines (Daudi and U266), demonstrating the specificity of transmembrane signaling for IFN-beta and IFN-alpha through the IFNAR chain.
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We describe the isolation and characterization of cDNAs encoding the precursor polypeptide of the 6.1-kDa polypeptide associated with the reaction center core of the photosystem II complex from spinach. PsbW, the gene encoding this polypeptide, is present in a single copy per haploid genome. The mature polypeptide with 54 amino acid residues is characterized by a hydrophobic transmembrane segment, and, although an intrinsic membrane protein, it carries a bipartite transit peptide of 83 amino acid residues which directs the N terminus of the mature protein into the chloroplast lumen. Thylakoid integration of this polypeptide does not require a delta pH across the membrane, nor is it azide-sensitive, suggesting that the polypeptide chain inserts spontaneously in an as yet unknown way. The PsbW mRNA levels are light regulated. Similar to cytochrome b559 and PsbS, but different from the chlorophyll-complexing polypeptides D1, D2, CP43, and CP47 of photosystem II, PsbW is present in etiolated spinach seedlings.
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Experimental information on the structure and dynamics of molten globules gives estimates for the energy landscape's characteristics for folding highly helical proteins, when supplemented by a theory of the helix-coil transition in collapsed heteropolymers. A law of corresponding states relating simulations on small lattice models to real proteins possessing many more degrees of freedom results. This correspondence reveals parallels between "minimalist" lattice results and recent experimental results for the degree of native character of the folding transition state and molten globule and also pinpoints the needs of further experiments.