6,981 research outputs found
Finite universe of discourse. The systems biology of Walter Elsasser (1904-1991).
No full textWalter Elsasser (1904-1991), an eminent quantum physicist and geophysicist, was also active in theoretical biology over a 35-year period from the early 1950s to the late 1980s. Although increasingly estranged from the biological establishment during the last fifteen years of his life, Elsasser's central concern with complexity has resulted in a revival of interest in his theories over the last decade, particularly among those who see biology from a systems holist rather than a molecular reductionist viewpoint. This article reviews the development of Elsasser's thought from his early opposition to genetic determinism, through the radical epistemology of his middle period, to his later more broadly philosophical ideas. After a summary of existing responses to Elsasser in the literature, a fresh critique and assessment of his work is presented, with particular attention to the implications for systems biology. It is concluded that although Elsasser drew some conclusions from his epistemology that are not justifiable in the light of subsequent research, his insistence on the existence of biotonic phenomena in biology, irreducible (either at present, or in principle) to physics, is correct. Ironically, the most significant biotonic principle is one which Elsasser largely ignored in his own work, that of Natural Selection
TACC3-ch-TOG track the growing tips of microtubules independently of clathrin and Aurora-A phosphorylation
No full textThe interaction between TACC3 (transforming acidic coiled coil protein 3) and the microtubule polymerase ch-TOG (colonic, hepatic tumor overexpressed gene) is evolutionarily conserved. Loading of TACC3–ch-TOG onto spindle microtubules requires the phosphorylation of TACC3 by Aurora-A kinase and the subsequent interaction of TACC3 with clathrin to form a microtubule binding surface. Whether there is a pool of TACC3–ch-TOG that is independent of clathrin in human cells, and what is the function of this pool, are open questions. Here, we report that TACC3 is recruited to the plus-ends of microtubules by its association with ch-TOG and that this pool is independent of phosphorylation and binding to clathrin. The plus-end binding of TACC3–ch-TOG persists in interphase and we propose that one cellular function of TACC3–ch-TOG is to modulate cell migration. We also describe the distinct subcellular pools of TACC3, ch-TOG and clathrin. TACC3 is often described as a centrosomal protein, but we show that there is no significant population of TACC3 at centrosomes. The delineation of distinct protein pools reveals a simplified view of how these proteins are organized and controlled by post-translational modification
First Evidence for the Decay B-s(0) -> mu(+) mu(-)
No full textA search for the rare decays Bs0→μ+μ- and B0→μ+μ- is performed with data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1 fb-1 of proton-proton collisions at √s=8 TeV and 1.0 fb-1 at √s=7 TeV. We observe an excess of Bs0→μ+μ- candidates with respect to the background expectation. The probability that the background could produce such an excess or larger is 5.3×10-4 corresponding to a signal significance of 3.5 standard deviations. A maximum-likelihood fit gives a branching fraction of B(Bs0→μ+μ-)=(3.2-1.2+1.5)×10-9, where the statistical uncertainty is 95% of the total uncertainty. This result is in agreement with the standard model expectation. The observed number of B0→μ+μ- candidates is consistent with the background expectation, giving an upper limit of B(B0→μ+μ-)<9.4×10-10 at 95% confidence level
Les diminutifs basques avec ch
No full textSe presentan formaciones similares a los diminutivos vascos con "ch" en España y América latina. Se dan ejemplosThe author introduces similar formations to the Basque diminutive "ch" in Spain and Latin America. Examples are provide
COUPLING OF THE C-H STRETCH TO LARGE-AMPLITUDE TORSION AND INVERSION MOTIONS: COMPARISON OF CHCH, CHOH AND CHNH
No full textAuthor Institution: Department of Polymer Science and Department of Chemistry, The University of Akron; Department of Chemistry, The University of Akron, OH 44325In each of the title molecules, torsional and inversion tunneling occurs between six equivalent minima. Coupling of these degrees of freedom to the CH stretch occurs via variation of the C-H stretching force constants as a function of the torsional () and inversion () angles. Maps of the couplings have been computed at the MP2/6-311++G(3df,2p) level. Both the single bond CH stretch force constants and the bilinear couplings between CH bonds are presented as a function of and . Although the torsional barriers differ by more than a factor of 20, the torsion-inversion-vibration coupling patterns are very similar for CHNH and CHCH. On the other hand, the torsion-inversion-vibration coupling in the charged species CHOH is much weaker
Reply to the Ch. Lagrange’s note
No full textThe author answers to a Ch. Lagrange’s note who refutes his theory on the diurnal nutation.L’auteur répond à une note de Ch. Lagrange qui réfute sa théorie sur la nutation diurne
NATURE OF TORSION-INVERSION COUPLING IN CHNH, CHOH AND CHCH
No full textAuthor Institution: Department of Chemistry, The University of Akron, OH; 44325-3601Two-dimensional torsion-inversion surfaces for methylamine, protonated methanol and ethyl radical were calculated and fit to a function containing a polynomial in the inversion angle() and trigonometric functions of the torsional angle(). Calculations were done at the B3LYP, MP2, and CCSD(T) levels with the 6-311++G(d,p) and 6-311++G(3df, 2p) basis sets and partial optimization. CHNH, CHOH and CHCH have G symmetry with 6-equivalent minima which are located by the various calculations at inversion angles 6.5 to 11; 42 to 45.5 and 52.5 to 55 degrees respectively on either side of planar. The three molecules have very different barriers to inversion ranging from no barrier for CHCH to 838 cm for CHOH to 1837 cm for CHNH. The dominant torsion-inversion coupling term in all cases has the form
Note about Mr. Ch. Lagrange’s recent communication
No full textThe author establishes a note about Mr. Ch. Lagrange’s communication on the Eulerian nutation period.L’auteur établit une note au sujet d’une communication de Ch. Lagrande sur la période de la nutation eulérienne
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Using δ¹³C-CH₄ and δD-CH₄ to constrain Arctic methane emissions
No full text© Author(s) 2016.We present a global methane modelling study assessing the sensitivity of Arctic atmospheric CH₄ mole fractions, δ¹³C-CH₄ and δD-CH₄ to uncertainties in Arctic methane sources. Model simulations include methane tracers tagged by source and isotopic composition and are compared with atmospheric data at four northern high-latitude measurement sites. We find the model's ability to capture the magnitude and phase of observed seasonal cycles of CH₄ mixing ratios, δ¹³C-CH₄ and δD-CH₄ at northern high latitudes is much improved using a later spring kick-off and autumn decline in northern high-latitude wetland emissions than predicted by most process models. Results from our model simulations indicate that recent predictions of large methane emissions from thawing submarine permafrost in the East Siberian Arctic Shelf region could only be reconciled with global-scale atmospheric observations by making large adjustments to high-latitude anthropogenic or wetland emission inventories
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