Symmetry Breaking and Time Variation of Gauge Couplings

Astrophysical indications that the fine structure constant has undergone a small time variation during the cosmological evolution are discussed within the framework of the standard model of the electroweak and strong interactions and of grand unification. A variation of the electromagnetic coupling constant could either be generated by a corresponding time variation of the unified coupling constant or by a time variation of the unification scale, of by both. The various possibilities, differing substantially in their implications for the variation of low energy physics parameters like the nuclear mass scale, are discussed. The case in which the variation is caused by a time variation of the unification scale is of special interest. It is supported in addition by recent hints towards a time change of the proton-electron mass ratio. Implications for the analysis of the Oklo remains and for quantum optics tests are discussed.Comment: 9 page

Quartet S Wave Neutron Deuteron Scattering in Effective Field Theory

The real and imaginary part of the quartet S wave phase shift in nd scattering (^4 S_{3/2}) for centre-of-mass momenta of up to 300 MeV (E_cm \approx 70 MeV) is presented in effective field theory, using both perturbative pions and a theory in which pions are integrated out. As available, the calculation agrees with both experimental data and potential model calculations, but extends to a higher, so far untested momentum r\'egime above the deuteron breakup point. A Lagrangean more feasible for numerical computations is derived.Comment: 27 pages LaTeX2e with 11 figures, uses packages includegraphicx (6 .eps files), color and feynmp (necessary Metapost files included). Corrections in bibliography and NNLO results added above breaku

Higher Partial Waves in an Effective Field Theory Approach to nd Scattering

The phase shifts for the higher partial waves (l\ge 1) in the spin quartet and doublet channel of nd scattering at centre-of-mass energies up to 15 MeV are presented at next-to-leading and next-to-next-to-leading order in an effective field theory in which pions are integrated out. As available, the results agree with both phase shift analyses and potential model calculations.Comment: 23 pages LaTeX2e with 8 figures, uses packages includegraphicx (18 .eps files), amssymb, color and feynmp (necessary Metapost files included). Petty changes, version for publication in Nucl. Phys.

A Symmetry Pattern of Maximal CP-Violation and a Determination of the Unitarity Triangle

Within a specific texture of the quark mass matrix the notion of a maximal violation of the $CP$ symmetry can be defined. The experimental constraints from weak decays imply that in reality one is close to the case of maximal $CP$ violation, which vanishes as the mass of the $u$--quark approaches zero. The unitarity triangle of the Cabibbo--Kobayashi--Maskawa matrix elements is determined. It is related to the triangle relating the Cabibbo angle to the quark mass ratios in the complex plane. The angle $\alpha$ describing the $CP$ violation in the decay $B_d \rightarrow \pi^+ \pi^-$ is close to 90$^{\circ }$.Comment: 7 latex page

Microbial Cell Factories / Pichia pastoris Aft1 - a novel transcription factor, enhancing recombinant protein secretion

Background: The methylotrophic yeast Pichia pastoris is frequently used for the production of recombinant proteins. However, expression levels can vary depending on the target protein. Allowing for simultaneous regulation of many genes, which may elicit a desired phenotype like increased protein production, overexpression of transcription factors can be used to overcome expression bottlenecks. Here, we present a novel P. pastoris transcription factor currently annotated as Aft1, activator of ferrous transport. Results: The promoter regions of key secretory P. pastoris genes were screened for fungal transcription factor binding sites, revealing Aft1 as an interesting candidate for improving secretion. Genome wide analysis of transcription factor binding sites suggested Aft1 to be involved in the regulation of many secretory genes, but also indicated possible novel functions in carbohydrate metabolism. No Aft binding sites were found in promoters of characteristic iron homeostasis genes in P. pastoris. Microarrays were used to study the Aft1 regulon in detail, confirming Aft1 involvement in the regulation of carbon-responsive genes, and showing that iron regulation is dependent on FEP1, but not AFT1 expression levels. The positive effect of AFT1 overexpression on recombinant protein secretion was demonstrated for a carboxylesterase from Sphingopyxis sp. MTA144, for which secretion was improved 2.5-fold in fed batch bioreactor cultivations. Conclusion: This study demonstrates that the transcription factor Aft1 can be used to improve recombinant protein secretion in P. pastoris. Furthermore, we discovered possible novel functions of Aft1 in carbohydrate metabolism and provide evidence arguing against a direct role of Aft1 in P. pastoris iron regulation

The adsorption of biomolecules to multi-walled carbon nanotubes is influenced by both pulmonary surfactant lipids and surface chemistry

<p>Abstract</p> <p>Background</p> <p>During production and processing of multi-walled carbon nanotubes (MWCNTs), they may be inhaled and may enter the pulmonary circulation. It is essential that interactions with involved body fluids like the pulmonary surfactant, the blood and others are investigated, particularly as these interactions could lead to coating of the tubes and may affect their chemical and physical characteristics. The aim of this study was to characterize the possible coatings of different functionalized MWCNTs in a cell free environment.</p> <p>Results</p> <p>To simulate the first contact in the lung, the tubes were coated with pulmonary surfactant and subsequently bound lipids were characterized. The further coating in the blood circulation was simulated by incubating the tubes in blood plasma. MWCNTs were amino (NH₂)- and carboxyl (-COOH)-modified, in order to investigate the influence on the bound lipid and protein patterns. It was shown that surfactant lipids bind unspecifically to different functionalized MWCNTs, in contrast to the blood plasma proteins which showed characteristic binding patterns. Patterns of bound surfactant lipids were altered after a subsequent incubation in blood plasma. In addition, it was found that bound plasma protein patterns were altered when MWCNTs were previously coated with pulmonary surfactant.</p> <p>Conclusions</p> <p>A pulmonary surfactant coating and the functionalization of MWCNTs have both the potential to alter the MWCNTs blood plasma protein coating and to determine their properties and behaviour in biological systems.</p

Quinaprilat during cardioplegic arrest in the rabbit to prevent ischemia-reperfusion injury

AbstractObjectives: This study evaluated intracardiac angiotensin-converting enzyme inhibition as an adjuvant to cardioplegia and examined its effects on hemodynamic, metabolic, and ultrastructural postischemic outcomes. Methods: The experiments were performed with an isolated, erythrocyte-perfused, rabbit working-heart model. The hearts excised from 29 adult New Zealand White rabbits (2950 ± 200 g) were randomly assigned to four groups. Two groups received quinaprilat (1 μg/mL), initiated either with cardioplegia (n = 7) or during reperfusion (n = 7). The third group received l-arginine (2 mmol/L) initiated with cardioplegia (n = 7). Eight hearts served as a control group. Forty minutes of preischemic perfusion were followed by 60 minutes of hypothermic arrest and 40 minutes of reperfusion. Results: All treatments substantially improved postischemic recovery of external heart work (62% ± 6%, 69% ± 3%, and 64% ± 5% in quinaprilat during cardioplegia, quinaprilat during reperfusion, and l-arginine groups, respectively, vs 35% ± 5% in control group, P <.001) with similarly increased external stroke work and cardiac output. When administered during ischemia, quinaprilat significantly improved recovery of coronary flow (70% ± 8%, P =.028 vs quinaprilat during reperfusion [49% ± 5%] and P =.023 vs control [48% ± 6%]). l-Arginine (55% ± 7%) showed no significant effect. Postischemic myocardial oxygen consumption remained low in treatment groups (4.6 ± 1.2 mL · min−1 · 100 g−1, 6.0 ± 2.2 mL · min−1 · 100 g−1, and 4.7 ± 1.6 mL · min−1 · 100 g−1 in quinaprilat during cardioplegia, quinaprilat during reperfusion, and l-arginine groups, respectively, vs 4.2 ± 0.8 mL · min−1 · 100 g−1 in control group), even though cardiac work was markedly increased. High-energy phosphates, which were consistently elevated in all treatment groups, showed a significant increase in adenosine triphosphate with quinaprilat during ischemia (2.24 ± 0.14 μmol/g vs 1.81 ± 0.12 μmol/g in control group, P =.040). Ultrastructural grading of mitochondrial damage revealed best preservation with quinaprilat during ischemia (100% [no damage], P =.001 vs control). Conclusion: These experimental findings have clinical relevance regarding prevention of postoperative myocardial stunning and low coronary reflow in patients undergoing heart surgery.J Thorac Cardiovasc Surg 2002;124:352-6

The Breaking of Subnuclear Democracy as the Origin of Flavour Mixing

It is shown that the simplest breaking of the subnuclear democracy leads to a successful description of the mixing between the second and third family. In the lepton channel the $\nu _{\mu } - \nu_{\tau }$ oscillations are expected to be described by a mixing angle of $2.65^ {\circ }$ which might be observed soon in neutrino experiments.Comment: 9 pages LaTeX, CERN-TH.7236/9

Four-Zero Texture of Hermitian Quark Mass Matrices and Current Experimental Tests

We show that the four-zero texture of Hermitian quark mass matrices can survive current experimental tests: it is able to yield sufficiently large predictions for the flavor mixing parameter $|V_{ub}/V_{cb}|$ and the CP-violating parameter $\sin 2\beta$, without fine-tuning of the input values of quark masses, provided the (2,2), (2,3) and (3,3) elements of up and down mass matrices roughly satisfy a geometrical hierarchy. The successful relations $|V_{us}| \approx \sqrt{m_u/m_c + m_d/m_s}$ and $|V_{td}/V_{ts}| \approx \sqrt{m_d/m_s}$ obtained previously from the six-zero texture of Hermitian quark mass matrices remain unchanged in the new ansatz.Comment: LaTex 9 page