175 research outputs found
Mermin-Ho vortex in ferromagnetic spinor Bose-Einstein condensates
The Mermin-Ho and Anderson-Toulouse coreless non-singular vortices are
demonstrated to be thermodynamically stable in ferromagnetic spinor
Bose-Einstein condensates with the hyperfine state F=1. The phase diagram is
established in a plane of the rotation drive vs the total magnetization by
comparing the energies for other competing non-axis-symmetric or singular
vortices. Their stability is also checked by evaluating collective modes.Comment: 4 pages, 4 figure
Life-long endurance exercise in humans:circulating levels of inflammatory markers and leg muscle size
Axisymmetric versus Non-axisymmetric Vortices in Spinor Bose-Einstein Condensates
The structure and stability of various vortices in F=1 spinor Bose-Einstein
condensates are investigated by solving the extended Gross-Pitaevskii equation
under rotation. We perform an extensive search for stable vortices, considering
both axisymmetric and non-axisymmetric vortices and covering a wide range of
ferromagnetic and antiferromagnetic interactions. The topological defect called
Mermin-Ho (Anderson-Toulouse) vortex is shown to be stable for ferromagnetic
case. The phase diagram is established in a plane of external rotation Omega vs
total magnetization M by comparing the free energies of possible vortices. It
is shown that there are qualitative differences between axisymmetric and
non-axisymmetric vortices which are manifested in the Omega- and M-dependences.Comment: 9 pages, 9 figure
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Small States in the Rearview Mirror: Legitimacy in the Management of Economy and Society
Small States in World Markets is about political efficacy and legitimation rather than scoring who is ahead in the economic sweepstakes. Its case for democratic corporatism rests on norms, particularly stability, rather than on narrow measures of economic efficiency. But stability and the efficacious management of the economy and social problems requires a degree of technocracy that undermines the legitimacy of the management process itself by helping to produce populist revolts
Vortices in multicomponent Bose-Einstein condensates
We review the topic of quantized vortices in multicomponent Bose-Einstein
condensates of dilute atomic gases, with an emphasis on that in two-component
condensates. First, we review the fundamental structure, stability and dynamics
of a single vortex state in a slowly rotating two-component condensates. To
understand recent experimental results, we use the coupled Gross-Pitaevskii
equations and the generalized nonlinear sigma model. An axisymmetric vortex
state, which was observed by the JILA group, can be regarded as a topologically
trivial skyrmion in the pseudospin representation. The internal, coherent
coupling between the two components breaks the axisymmetry of the vortex state,
resulting in a stable vortex molecule (a meron pair). We also mention
unconventional vortex states and monopole excitations in a spin-1 Bose-Einstein
condensate. Next, we discuss a rich variety of vortex states realized in
rapidly rotating two-component Bose-Einstein condensates. We introduce a phase
diagram with axes of rotation frequency and the intercomponent coupling
strength. This phase diagram reveals unconventional vortex states such as a
square lattice, a double-core lattice, vortex stripes and vortex sheets, all of
which are in an experimentally accessible parameter regime. The coherent
coupling leads to an effective attractive interaction between two components,
providing not only a promising candidate to tune the intercomponent interaction
to study the rich vortex phases but also a new regime to explore vortex states
consisting of vortex molecules characterized by anisotropic vorticity. A recent
experiment by the JILA group vindicated the formation of a square vortex
lattice in this system.Comment: 69 pages, 25 figures, Invited review article for International
Journal of Modern Physics
Natural CD4+ T-Cell Responses against Indoleamine 2,3-Dioxygenase
The enzyme indoleamine 2,3-dioxygenase (IDO) contributes to immune tolerance in a variety of settings. In cancer IDO is expressed within the tumor itself as well as in antigen-presenting cells in tumor-draining lymph nodes, where it endorses the establishment of peripheral immune tolerance to tumor antigens. Recently, we described cytotoxic CD8(+) T-cell reactivity towards IDO-derived peptides.In the present study, we show that CD4(+) helper T cells additionally spontaneously recognize IDO. Hence, we scrutinized the vicinity of the previously described HLA-A*0201-restricted IDO-epitope for CD4(+) T-cell epitopes. We demonstrated the presence of naturally occurring IDO-specific CD4(+) T cells in cancer patients and to a lesser extent in healthy donors by cytokine release ELISPOT. IDO-reactive CD4(+) T cells released IFN-γ, TNF-α, as well as IL-17. We confirm HLA class II-restriction by the addition of HLA class II specific blocking antibodies. In addition, we detected a trend between class I- and class II-restricted IDO responses and detected an association between IDO-specific CD4(+) T cells and CD8(+) CMV-responses. Finally, we could detect IL-10 releasing IDO-reactive CD4(+) T cells.IDO is spontaneously recognized by HLA class II-restricted, CD4(+) T cells in cancer patients and in healthy individuals. IDO-specific T cells may participate in immune-regulatory networks where the activation of pro-inflammatory IDO-specific CD4(+) responses may well overcome or delay the immune suppressive actions of the IDO-protein, which are otherwise a consequence of the early expression of IDO in maturing antigen presenting cells. In contrast, IDO-specific regulatory T cells may enhance IDO-mediated immune suppression
Regulation of Clock-Controlled Genes in Mammals
The complexity of tissue- and day time-specific regulation of thousands of clock-controlled genes (CCGs) suggests that many regulatory mechanisms contribute to the transcriptional output of the circadian clock. We aim to predict these mechanisms using a large scale promoter analysis of CCGs
Bacterial Surface Appendages Strongly Impact Nanomechanical and Electrokinetic Properties of Escherichia coli Cells Subjected to Osmotic Stress
The physicochemical properties and dynamics of bacterial envelope, play a major role in bacterial activity. In this study, the morphological, nanomechanical and electrohydrodynamic properties of Escherichia coli K-12 mutant cells were thoroughly investigated as a function of bulk medium ionic strength using atomic force microscopy (AFM) and electrokinetics (electrophoresis). Bacteria were differing according to genetic alterations controlling the production of different surface appendages (short and rigid Ag43 adhesins, longer and more flexible type 1 fimbriae and F pilus). From the analysis of the spatially resolved force curves, it is shown that cells elasticity and turgor pressure are not only depending on bulk salt concentration but also on the presence/absence and nature of surface appendage. In 1 mM KNO3, cells without appendages or cells surrounded by Ag43 exhibit large Young moduli and turgor pressures (∼700–900 kPa and ∼100–300 kPa respectively). Under similar ionic strength condition, a dramatic ∼50% to ∼70% decrease of these nanomechanical parameters was evidenced for cells with appendages. Qualitatively, such dependence of nanomechanical behavior on surface organization remains when increasing medium salt content to 100 mM, even though, quantitatively, differences are marked to a much smaller extent. Additionally, for a given surface appendage, the magnitude of the nanomechanical parameters decreases significantly when increasing bulk salt concentration. This effect is ascribed to a bacterial exoosmotic water loss resulting in a combined contraction of bacterial cytoplasm together with an electrostatically-driven shrinkage of the surface appendages. The former process is demonstrated upon AFM analysis, while the latter, inaccessible upon AFM imaging, is inferred from electrophoretic data interpreted according to advanced soft particle electrokinetic theory. Altogether, AFM and electrokinetic results clearly demonstrate the intimate relationship between structure/flexibility and charge of bacterial envelope and propensity of bacterium and surface appendages to contract under hypertonic conditions
Advancing microbial sciences by individual-based modelling
Remarkable technological advances have revealed ever more properties and behaviours of individual microorganisms, but the novel data generated by these techniques have not yet been fully exploited. In this Opinion article, we explain how individual-based models (IBMs) can be constructed based on the findings of such techniques and how they help to explore competitive and cooperative microbial interactions. Furthermore, we describe how IBMs have provided insights into self-organized spatial patterns from biofilms to the oceans of the world, phage-CRISPR dynamics and other emergent phenomena. Finally, we discuss how combining individual-based observations with IBMs can advance our understanding at both the individual and population levels, leading to the new approach of microbial individual-based ecology (μIBE)
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