Ground state of a resonantly interacting Bose gas

We show that a two-channel mean-field theory for a Bose gas near a Feshbach resonance allows for an analytic computation of the chemical potential, and therefore the universal constant \beta, at unitarity. To improve on this mean-field theory, which physically neglects condensate depletion, we study a variational Jastrow ansatz for the ground-state wave function and use the hypernetted-chain approximation to minimize the energy for all positive values of the scattering length. We also show that other important physical quantities such as Tan's contact and the condensate fraction can be directly obtained from this approach.Comment: Replaced with published version; 11 pages, 7 figure

Cooling curves for neutron stars with hadronic matter and quark matter

The thermal evolution of isothermal neutron stars is studied with matter both in the hadronic phase as well as in the mixed phase of hadronic matter and strange quark matter. In our models, the dominant early-stage cooling process is neutrino emission via the direct Urca process. As a consequence, the cooling curves fall too fast compared to observations. However, when superfluidity is included, the cooling of the neutron stars is significantly slowed down. Furthermore, we find that the cooling curves are not very sensitive to the precise details of the mixing between the hadronic phase and the quark phase and also of the pairing that leads to superfluidity.Comment: 19 pages, 25 figure

Effect of the protein matrix of cytochrome c in supressing the inherent peroxidase activity of its heme group

Macromolecular Biochemistr

Peroxidase Activity as a Tool for Studying the Folding of c-Type Cytochromes

The peroxidase activity of c-type cytochromes increases substantially by unfolding. This phenomenon was used to study the equilibrium unfolding of ferricytochrome c. The peroxidase activity is already enhanced at low denaturant concentrations. The lowest free energy folding intermediate is easily detected by this method, while it is invisible using fluorescence or optical spectroscopy. The free energy difference between this folding intermediate and the native state depends on the strength of the sixth ligand of the heme-iron and the increase in peroxidase activity upon unfolding is shown to be a sensitive indicator of the strength of this ligand. Under fully denaturing conditions, the peroxidase activity is inhibited by protein-based ligands. It is shown that at least three different ligand groups can be responsible for this inhibition, and that at neutral or alkaline pH, the predominant ligand is not histidine. The use of peroxidase activity assays as a method to study the unfolding of cytochrome c is evaluated.Macromolecular Biochemistr

Observation of Field-Induced Transverse N\'{e}el Ordering in the Spin Gap System TlCuCl3_3

Neutron elastic scattering experiments have been performed on the spin gap system TlCuCl$_3$ in magnetic fields parallel to the $b$-axis. The magnetic Bragg peaks which indicate the field-induced N\'{e}el ordering were observed for magnetic field higher than the gap field $H_{\rm g}\approx 5.5$ T at $Q=(h, 0, l)$ with odd $l$ in the $a^*-c^*$ plane. The spin structure in the ordered phase was determined. The temperature and field dependence of the Bragg peak intensities and the phase boundary obtained were discussed in connection with a recent theory which describes the field-induced N\'{e}el ordering as a Bose-Einstein condensation of magnons.Comment: 4 pages, 5 eps figures, jpsj styl

The peroxidase activity of cytochrome c-550 from Paracoccus versutus

Macromolecular Biochemistr

A neutron scattering study of two-magnon states in the quantum magnet copper nitrate

We report measurements of the two-magnon states in a dimerized antiferromagnetic chain material, copper nitrate (Cu(NO3)2*2.5D2O). Using inelastic neutron scattering we have measured the one and two magnon excitation spectra in a large single crystal. The data are in excellent agreement with a perturbative expansion of the alternating Heisenberg Hamiltonian from the strongly dimerized limit. The expansion predicts a two-magnon bound state for q ~ (2n+1)pi*d which is consistent with the neutron scattering data.Comment: 11 pages of revtex style with 6 figures include

Increase of the peroxidase activity of cytochrome c-550 by the interaction with detergents

The effect was studied of detergents on the peroxidase activity of the heme-containing electron-transport protein, cytochrome c-550 from Paracoccus versutus (cytc550). Cytc550 does not interact with non-ionic or zwitterionic detergents, but its peroxidase activity is significantly enhanced in the presence of both anionic and cationic detergents. The increase in peroxidase activity is caused by (partial) unfolding of cytc550, resulting in weakening of the bond between the axial methionine ligand and the heme-iron. With sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB), the activity increases roughly 10- and 100-fold, respectively. The detergent concentration required to enhance the peroxidase activity of cytc550 consistently coincides with the critical micellisation concentration (CMC). When cytc550 carries substantial opposite charge to that of the detergent headgroup, the protein-detergent complex is formed at lower detergent concentration than the critical micellisation concentration, i.e. at acid pH for anionic detergent and at alkaline pH for cationic detergent. It is concluded that in the presence of ionic detergents, cytc550 can acquire considerable peroxidase activity. This may be exploited by applying cytc550 as an oxidative catalyst in detergent-rich environments, where regular peroxidases rapidly lose their catalytic potential. (C) 2003 Elsevier B.V. All rights reserved.Macromolecular Biochemistr

Morphotectonic interpretation of the Ibague fault for paleoseismological purposes

The Ibagué Fault is a WSW-ENE right-lateral strike-slip structure located in the central part of the Central Cordillera and in the middle of transverse shear zone that affects the Colombian Andes. Morphotectonic interpretations of the fault from satellite images allow us to propose the style of deformation and the kinematics of the structure. These structural characteristics together with geographical, geomorphologic, sedimentologic and climatic data are key elements for the right selection of a paleoseismical investigation site. The strand appears to be as a single line along the Ibagué Fan at regional scale. However, detailed studies shown several morphotectonic features characteristic of wrench tectonics. Riedel and en-echelon array indicate dextral displacements. Additionally, microtectonic data show a local stress tensor with a s1=311º/18 °±15 ° and a factor R=0,62, indicating a strike-slip regime, which is coherent with the observed geologic and morphotectonic features.  La Falla Ibagué es una estructura de tipo transcurrente dextral que se extiende en dirección WSW-ENE y se encuentra ubicada en medio de una zona de cizalla transversal que afecta la parte central de la Cordillera Central de Los Andes Colombianos con dirección NEE. Utilizando imágenes de sensores remotos se realizó una interpretación morfotectónica de la falla, que permitió proponer la geometría de deformación y algunas características cinemáticas, conocimiento que, junto con datos geográficos, morfoclimáticos y sedimentológicos, es básico para la elección acertada de un sitio de trinchera de exploración paleosismológica. El trayecto de la falla a lo largo del Abanico de Ibagué se muestra regionalmente como un solo trazo, pero a mayor escala se observan numerosos y variados rasgos morfotectónicos característicos de fallamiento transcurrente, caracterizados por presentar un arreglo de cizallas Riedel dextrales y en echelon con saltos a la izquierda. Las mediciones microtectónicas en estaciones situadas a lo largo de la falla en el Abanico de Ibagué arrojaron un tensor de esfuerzos local, con un esfuerzo máximo horizontal (s1) de dirección 311º/18° +/- 15° y un factor de forma de R=0,62, que indican un régimen de esfuerzos de tipo transcurrente, resultado que es consecuente con las observaciones morfotectónicas y geológicas.  &nbsp

Morphotectonic interpretation of the Ibague fault for paleoseismological purposes

The Ibagué Fault is a WSW-ENE right-lateral strike-slip structure located in the central part of the Central Cordillera and in the middle of transverse shear zone that affects the Colombian Andes. Morphotectonic interpretations of the fault from satellite images allow us to propose the style of deformation and the kinematics of the structure. These structural characteristics together with geographical, geomorphologic, sedimentologic and climatic data are key elements for the right selection of a paleoseismical investigation site. The strand appears to be as a single line along the Ibagué Fan at regional scale. However, detailed studies shown several morphotectonic features characteristic of wrench tectonics. Riedel and en-echelon array indicate dextral displacements. Additionally, microtectonic data show a local stress tensor with a s1=311º/18 °±15 ° and a factor R=0,62, indicating a strike-slip regime, which is coherent with the observed geologic and morphotectonic features.  La Falla Ibagué es una estructura de tipo transcurrente dextral que se extiende en dirección WSW-ENE y se encuentra ubicada en medio de una zona de cizalla transversal que afecta la parte central de la Cordillera Central de Los Andes Colombianos con dirección NEE. Utilizando imágenes de sensores remotos se realizó una interpretación morfotectónica de la falla, que permitió proponer la geometría de deformación y algunas características cinemáticas, conocimiento que, junto con datos geográficos, morfoclimáticos y sedimentológicos, es básico para la elección acertada de un sitio de trinchera de exploración paleosismológica. El trayecto de la falla a lo largo del Abanico de Ibagué se muestra regionalmente como un solo trazo, pero a mayor escala se observan numerosos y variados rasgos morfotectónicos característicos de fallamiento transcurrente, caracterizados por presentar un arreglo de cizallas Riedel dextrales y en echelon con saltos a la izquierda. Las mediciones microtectónicas en estaciones situadas a lo largo de la falla en el Abanico de Ibagué arrojaron un tensor de esfuerzos local, con un esfuerzo máximo horizontal (s1) de dirección 311º/18° +/- 15° y un factor de forma de R=0,62, que indican un régimen de esfuerzos de tipo transcurrente, resultado que es consecuente con las observaciones morfotectónicas y geológicas.  &nbsp