Ladder operators for integrable one-dimensional lattice models

A generalised ladder operator is used to construct the conserved operators for any one-dimensional lattice model derived from the Yang-Baxter equation. As an example, the low order conserved operators for the XYh model are calculated explicitly.

Evaluating curriculum changes in undergraduate cancer education

Background. Previous studies have indicated that Australian medical schools have not adequately prepared our graduating doctors to care for patients with cancer. The University of Western Australia (UWA) introduced a two-week clinical attachment in cancer medicine for fifth-year students in 2000 and a four-day clinical attachment in palliative care for sixth-year students in 2001. This article evaluates the introduction of these dedicated clinical attachments in cancer and palliative care. Method. The Australian Cancer Society's Cancer Education Survey was administered to the UWA graduates starting their intern year in teaching hospitals in Perth, Western Australia, in 2002. Their responses were compared with data collected in a similar national survey of Australian and New Zealand interns in 2001. Results. The response rate was 56% (n = 70). When compared with the national data for 2001, more UWA interns (2002) would refer a newly diagnosed breast cancer patient to a multidisciplinary breast clinic (97% vs. 74%, P<.001). Fewer UWA 2002 interns rated their training as poor or very poor in the management of patients with incurable cancer (19% vs. 35%, P=.008) and the management of symptoms in patients dying from cancer (10% vs. 37%, P<.001), but they were more likely to rate their training in assisting a patient to stop smoking as poor or very poor (54% vs. 21%, P<.001). Only a quarter of the UWA 2002 interns had examined a patient with a cancer of the mouth or tongue (25% vs. 49%, P<.001), and only two thirds had examined a patient with lymphoma (64% vs. 83%, P<.001). Conclusions. Our data reflect changes in the final two years of the medical course at UWA and suggest that the introduction of dedicated attachments in cancer and palliative care has better prepared graduating doctors to care for patients with cancer.

Molecular adaptability of nucleoside diphosphate kinase b from trypanosomatid parasites: stability, oligomerization and structural determinants of nucleotide binding

Nucleoside diphosphate kinases play a crucial role in the purine-salvage pathway of trypanosomatid protozoa and have been found in the secretome of Leishmania sp., suggesting a function related to host-cell integrity for the benefit of the parasite. Due to their importance for housekeeping functions in the parasite and by prolonging the life of host cells in infection, they become an attractive target for drug discovery and design. In this work, we describe the first structural characterization of nucleoside diphosphate kinases b from trypanosomatid parasites (tNDKbs) providing insights into their oligomerization, stability and structural determinants for nucleotide binding. Crystallographic studies of LmNDKb when complexed with phosphate, AMP and ADP showed that the crucial hydrogen-bonding residues involved in the nucleotide interaction are fully conserved in tNDKbs. Depending on the nature of the ligand, the nucleotide-binding pocket undergoes conformational changes, which leads to different cavity volumes. SAXS experiments showed that tNDKbs, like other eukaryotic NDKs, form a hexamer in solution and their oligomeric state does not rely on the presence of nucleotides or mimetics. Fluorescence-based thermal-shift assays demonstrated slightly higher stability of tNDKbs compared to human NDKb (HsNDKb), which is in agreement with the fact that tNDKbs are secreted and subjected to variations of temperature in the host cells during infection and disease development. Moreover, tNDKbs were stabilized upon nucleotide binding, whereas HsNDKb was not influenced. Contrasts on the surface electrostatic potential around the nucleotide-binding pocket might be a determinant for nucleotide affinity and protein stability differentiation. All these together demonstrated the molecular adaptation of parasite NDKbs in order to exert their biological functions intra-parasite and when secreted by regulating ATP levels of host cells.

Luminescent and morphological study of Sr(2)CeO(4) blue phosphor prepared from oxalate precursors

Luminescent and morphological studies of Sr(2)CeO(4) blue phosphor prepared from cerium-doped strontium oxalate precursor are reported Powder samples were prepared from 5 and 25 mol% Ce(3+)-doped strontium oxalate as well as from a mechanical mixture of strontium oxalate and cerium oxalate at a 4 1 ratio respectively All the samples were characterized by XRD IR PLS and SEM The luminescent and structural properties of the Sr(2)CeO(4) material are little affected by the SrCO(3) remaining from precursors The Sr(2)CeO(4) material consists in one-dimensional chains of edge-sharing CeO(6) octahedra that are linked together by Sr(2+) ions The carbonate ion might be associated with oxygen ions of the linear chain and also with the oxygen atoms located in the equatorial position which consequently affects the charge transfer bands between O(2-) and Ce(4+). As observed by SEM, the morphological changes are related to each kind of precursor and thermal treatment along with irregular powder particles within the size range 05-2 mu m (c) 2010 Elsevier B V All rights reserved

Changes in inflammatory mediators following eccentric exercise of the elbow flexors

The aims of this study were to examine the plasma concentrations of inflammatory mediators including cytokines induced by a single bout of eccentric exercise and again 4 weeks later by a second bout of eccentric exercise of the same muscle group. Ten untrained male subjects performed two bouts of the eccentric exercise involving the elbow flexors (6 sets of 5 repetitions) separated by four weeks. Changes in muscle soreness, swelling, and function following exercise were compared between the bouts. Blood was sampled before, immediately after, 1 h, 3 h, 6 h, 24 h (1 d), 48 h (2 d), 72 h (3 d), 96 h (4 d) following exercise bout to measure plasma creatine kinase (CK) activity, plasma concentrations of myoglobin (Mb), interleukin (IL)-1 beta, IL-1 receptor antagonist (IL-1ra), IL-4, IL-6, IL-8, IL-10, IL-12p40, tumor necrosis factor (TNF)-alpha, granulocyte colony-stimulating factor (G-CSF), myeloperoxidase (MPO), prostaglandin E-2 (PGE(2)), heat shock protein (HSP) 60 and 70. After the first bout, muscle soreness increased significantly, and there was also significant increase in upper arm circumference; muscle function decreased and plasma CK activity and Mb concentration increased significantly. These changes were significantly smaller after the second bout compared to the first bout, indicating muscle adaptation to the repeated bouts of the eccentric exercise. Despite the evidence of greater muscle damage after the first bout, the changes in cytokines and other inflammatory mediators were quite minor, and considerably smaller than that following endurance exercise. These results suggest that eccentric exercise-induced muscle damage is not associated with the significant release of cytokines into the systemic circulation. After the first bout, plasma G-CSF concentration showed a small but significant increase, whereas TNF-alpha and IL-8 showed significant decreases compared to the pre-exercise values. After the second bout, there was a significant increase in IL-10, and a significant decrease in IL-8. In conclusion, although there was evidence of severe muscle damage after the eccentric exercise, this muscle damage was not accompanied by any large changes in plasma cytokine concentrations. The minor changes in systemic cytokine concentration found in this study might reflect more rapid clearance from the circulation, or a lack of any significant metabolic or oxidative demands during this particular mode of exercise. In relation to the adaptation to the muscle damage, the anti-inflammatory cytokine IL-10 might work as one of the underlying mechanisms of action.

Signature of mott-insulator transition with ultracold fermions in a one-dimensional optical lattice

Using the exact Bethe ansatz solution of the Hubbard model and Luttinger liquid theory, we investigate the density profiles and collective modes of one-dimensional ultracold fermions confined in an optical lattice with a harmonic trapping potential. We determine a generic phase diagram in terms of a characteristic filling factor and a dimensionless coupling constant. The collective oscillations of the atomic mass density, a technique that is commonly used in experiments, provide a signature of the quantum phase transition from the metallic phase to the Mott-insulator phase. A detailed experimental implementation is proposed.

Asymptotic behaviour of two-dimensional time-delayed Navier-Stokes equations

We consider the two-dimensional Navier-Stokes equations with a time-delayed convective term and a forcing term which contains some hereditary features. Some results on existence and uniqueness of solutions are established. We discuss the asymptotic behaviour of solutions and we also show the exponential stability of stationary solutions.

Two-dimensional approximation for tidal dynamics in coastal aquifers: Capillarity correction

Most previous investigations on tide-induced watertable fluctuations in coastal aquifers have been based on one-dimensional models that describe the processes in the cross-shore direction alone, assuming negligible along-shore variability. A recent study proposed a two-dimensional approximation for tide-induced watertable fluctuations that took into account coastline variations. Here, we further develop this approximation in two ways, by extending the approximation to second order and by taking into account capillary effects. Our results demonstrate that both effects can markedly influence watertable fluctuations. In particular, with the first-order approximation, the local damping rate of the tidal signal could be subject to sizable errors.

Finite-temperature correlations and density profiles of an inhomogeneous interacting one-dimensional Bose gas

We calculate the density profiles and density correlation functions of the one-dimensional Bose gas in a harmonic trap, using the exact finite-temperature solutions for the uniform case, and applying a local density approximation. The results are valid for a trapping potential that is slowly varying relative to a correlation length. They allow a direct experimental test of the transition from the weak-coupling Gross-Pitaevskii regime to the strong-coupling, fermionic Tonks-Girardeau regime. We also calculate the average two-particle correlation which characterizes the bulk properties of the sample, and find that it can be well approximated by the value of the local pair correlation in the trap center.

Double diffusion-driven convective instability of three-dimensional fluid-saturated geological fault zones heated from below

We conduct a theoretical analysis to investigate the double diffusion-driven convective instability of three-dimensional fluid-saturated geological fault zones when they are heated uniformly from below. The fault zone is assumed to be more permeable than its surrounding rocks. In particular, we have derived exact analytical solutions to the total critical Rayleigh numbers of the double diffusion-driven convective flow. Using the corresponding total critical Rayleigh numbers, the double diffusion-driven convective instability of a fluid-saturated three-dimensional geological fault zone system has been investigated. The related theoretical analysis demonstrates that: (1) The relative higher concentration of the chemical species at the top of the three-dimensional geological fault zone system can destabilize the convective flow of the system, while the relative lower concentration of the chemical species at the top of the three-dimensional geological fault zone system can stabilize the convective flow of the system. (2) The double diffusion-driven convective flow modes of the three-dimensional geological fault zone system are very close each other and therefore, the system may have the similar chance to pick up different double diffusion-driven convective flow modes, especially in the case of the fault thickness to height ratio approaching 0. (3) The significant influence of the chemical species diffusion on the convective instability of the three-dimensional geological fault zone system implies that the seawater intrusion into the surface of the Earth is a potential mechanism to trigger the convective flow in the shallow three-dimensional geological fault zone system.

On Reciprocal Illumination and Consilience in Biogeography

Biogeography deals with the combined analysis of the spatial and temporal components of the evolutionary process. To this purpose, biogeographical analysis should consider two extra steps: a reciprocal illumination step, and a consilience step. Even if the traditional challenges of biogeography were successfully handled, the obtained hypothesis is not necessarily meaningful in biogeographical terms--it needs continuous test in the light of external hypotheses. For this reason, a concept analogous to Hennig`s reciprocal illumination is valuable, as well as a sort of biogeographical consilience in Whewell`s sense. Firstly, through the search for different classes of evidence, information useful to improve the hypothesis can be accessed via reciprocal illumination. Following, a more general hypothesis would arise through a consilience process, when the hypothesis explains phenomena not contemplated during its construction, as the distribution of other taxa or the existence (or absence) of fossils. This procedure aims to evaluate the robustness of biogeographical hypotheses as scientific theories. Such theories are reliable descriptions of how life changes its form both in space and time, putting historical biogeography close to Croizat`s statement of evolution as a three dimensional phenomenon.