Pattern formation of microtubules and motors: inelastic interaction of polar rods

We derive a model describing spatio-temporal organization of an array of microtubules interacting via molecular motors. Starting from a stochastic model of inelastic polar rods with a generic anisotropic interaction kernel we obtain a set of equations for the local rods concentration and orientation. At large enough mean density of rods and concentration of motors, the model describes orientational instability. We demonstrate that the orientational instability leads to the formation of vortices and (for large density and/or kernel anisotropy) asters seen in recent experiments.Comment: 4 pages, 5 figures, to appear in Phys. Rev. E, Rapid Communication

Toll‐like receptor signalling induces the expression of serum amyloid A in epidermal keratinocytes and dermal fibroblasts

BACKGROUND: Toll-like receptors (TLRs) play critical roles in innate immune response by sensing pathogen- or damage-associated molecular patterns. Epidermal keratinocytes and dermal fibroblasts also produce proinflammatory cytokines and chemokines under stimulation with TLR ligands. Serum amyloid A (SAA) is an essential factor in the pathogenesis of secondary amyloidosis, and also has immunomodulatory functions. SAA are produced mainly by hepatocytes but also by a variety of cells, including immune cells, endothelial cells, synoviocytes, and epidermal keratinocytes. However, SAA expression in human dermal fibroblasts has not been shown to date. AIM: To investigate the effect of TLR ligands on SAA expression in epidermal keratinocytes and dermal fibroblasts. METHODS: We investigated whether TLR ligands induce the expression of SAA in normal human epidermal keratinocytes (NHEKs) and normal human dermal fibroblasts (NHDFs) by real-time quantitative PCR and ELISA. The effect of SAA on its own expression in NHDFs was also studied. RESULTS: SAA expression was induced via nuclear factor-κB by TLR1/2, 3, 5 and 2/6 ligands in NHEKs. In NHDFs, TLR1/2 and TLR2/6 ligands increased SAA expression. SAA further induced its own expression via TLR1/2 and NF-κB in NHDFs, as previously reported for NHEKs. CONCLUSIONS: Our results provide new evidence that the skin's innate immune response contributes to the production of SAA, which might lead to an increased risk of systemic complications such as secondary amyloidosis of recessive dystrophic epidermolysis bullosa

Self-organization and Mechanical Properties of Active Filament Bundles

A phenomenological description for active bundles of polar filaments is presented. The activity of the bundle results from crosslinks, that induce relative displacements between the aligned filaments. Our generic description is based on momentum conservation within the bundle. By specifying the internal forces, a simple minimal model for the bundle dynamics is obtained, capturing generic dynamic behaviors. In particular, contracted states as well as solitary and oscillatory waves appear through dynamic instabilities. The introduction of filament adhesion leads to self-organized persistent filament transport. Furthermore, calculating the tension, homogeneous bundles are shown to be able to actively contract and to perform work against external forces. Our description is motivated by dynamic phenomena in the cytoskeleton and could apply to stress-fibers and self-organization phenomena during cell-locomotion.Comment: 19 pages, 10 figure

Cathelicidin antimicrobial peptide LL-37 augments interferon-beta expression and antiviral activity induced by double-stranded RNA in keratinocytes

Background Cathelicidin antimicrobial peptide LL-37 has the capacity to kill a wide range of microbes and to modify host immunity. Recently, our group observed that the activation of keratinocytes by LL-37 and DNA greatly increases interferon (IFN)-beta through Toll-like receptor (TLR) 9. However, the effect of LL-37 on the induction of IFN-beta through TLR3, a sensor of double-stranded (ds) RNA, in keratinocytes is not well known. Objectives To investigate whether LL-37 could affect TLR3 signalling and antiviral activity in normal human epidermal keratinocytes (NHEKs). Methods We investigated the production of IFN-beta in NHEKs stimulated with a TLR3 ligand, poly (I:C), in the presence of LL-37. To examine the effect of LL-37 and poly (I:C) on antiviral activity, a virus plaque assay using herpes simplex (HS) virus type-1 was carried out. The uptake of poly (I:C) conjugated with fluorescein isothiocyanate (FITC) into the keratinocytes was observed in the presence of LL-37. Immunostaining for TLR3 and LL-37 was performed using skin samples from HS. Results LL-37 and poly (I:C) synergistically induced the expression of IFN-beta in NHEKs. Furthermore, co-stimulation with LL-37 and poly (I:C) significantly decreased the viral plaque numbers compared with poly (I:C) or LL-37 alone. LL-37 enhanced the uptake of FITC-conjugated poly (I:C) into cells. Immunohistochemical analysis demonstrated that the expression of TLR3 and LL-37 is up-regulated in HS lesions. Conclusions Our findings suggest that LL-37 augments the antiviral activity induced by dsRNA in keratinocytes, which may contribute to the innate immune response to cutaneous viral infections such as HS

Switched reluctance motor design for electric vehicles based on harmonics and back EMF analysis

Permanent magnet synchronous motors are widely accepted in automotive applications. The high torque density, high rotational speed with maximum efficiency in electric vehicle applications is technically challenging for motor design. However, these machines are expensive and difficult to work at high-temperature harsh environment due to permanent magnets demagnetisation features. Alternatively, switched reluctance motors can provide similar output characteristics and a wider speed. Thus these are considered to be more fault tolerant and more reliable. This study proposes a 20 kW, three-phase switched reluctance motor and analyse its overall performance and harmonic contents. The study is conducted by optimising the slot filling factor, excitation voltage and switching sequence of an asymmetrical half bridge converter. A finite element model is used to predict the core and copper losses and other influencing parameters. Simulation results are presented and analysed the effectiveness of the proposed switched reluctance motor (SRM)

Efeito da acupuntura na melhora da dor, sono e qualidade de vida em pacientes fibromiálgicos: estudo preliminar

Fibromyalgia is a syndrome defined by chronic widespread pain and sensitivity to pressure at at least 11 of 18 tender points. The aim of this random blind clinical trial was to assess the effectiveness of acupuncture on pain relief, on quality of sleep and life in fibromyalgia patients. From 20 female fibromyalgic patients (diagnosed according to the American College of Rheumatology), mean aged 44 years, 12 completed the study, randomly assigned into two groups: group A (GA, n=5) received acupuncture according to the traditional Chinese medicine; and group B (GB, n=7) received acupuncture at eight tender points: at the occiput, trapezius muscle, supraspinatus muscle, and lateral epicondyle. Pain was assessed by a visual analogue scale and by dolorimetry; quality of life, by the Fibromyalgia Impact Questionnaire (FIQ); and sleep, by the Post Sleep Inventory. Both groups received acupuncture once a week for eight weeks, with insertion of eight needles for 25 minutes. Data were statistically analysed and significance level set at ±=0.05. Results show significant sleep improvement in GA; and, in GB, lesser pain as detected by VAS, higher pain threshold on tender points, better sleep and improvement in FIQ items pain, morning tiredness, anxiety, and depression (pA fibromialgia é uma síndrome definida por dor crônica generalizada e em pelo menos 11 dos 18 tender points, pontos dolorosos específicos. Este ensaio clínico randômico visou verificar a eficácia da acupuntura na melhora da dor, sono e qualidade de vida de pacientes fibromiálgicas. Dentre 20 mulheres com média de idade 44 anos, com diagnóstico de fibromialgia segundo critérios do Colégio Americano de Reumatologia, finalizaram o estudo 12, distribuídas aleatoriamente em dois grupos: A (GA, n=5), que recebeu acupuntura segundo a medicina tradicional chinesa; e B (GB, n=7), que teve a inserção de agulhas nos tender points base do occipital, trapézio, supraespinhoso e epicôndilo lateral. A dor foi avaliada por escala visual analógica e dolorimetria; o sono, pelo Inventário do Sono; e a qualidade de vida, pelo Questionário de Impacto da Fibromialgia (QIF). Os grupos receberam acupuntura uma vez por semana, durante oito semanas, com inserção de oito agulhas por 25 minutos. Os dados foram tratados estatisticamente, adotando-se o nível de significância ±=0,05. No GA, houve melhora estatisticamente significante do sono; e no GB, na dor, limiar de dor nos tender points, no sono e nos itens do QIF dor, cansaço matinal, ansiedade e depressão (

An evaluation of metal removal during wastewater treatment: The potential to achieve more stringent final effluent standards

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2011 Taylor & Francis.Metals are of particular importance in relation to water quality, and concern regarding the impact of these contaminants on biodiversity is being encapsulated within the latest water-related legislation such as the Water Framework Directive in Europe and criteria revisions to the Clean Water Act in the United States. This review undertakes an evaluation of the potential of 2-stage wastewater treatment consisting of primary sedimentation and biological treatment in the form of activated sludge processes, to meet more stringent discharge consents that are likely to be introduced as a consequence. The legislation, sources of metals, and mechanisms responsible for their removal are discussed, to elucidate possible pathways by which the performance of conventional processes may be optimized or enhanced. Improvements in effluent quality, achievable by reducing concentrations of suspended solids or biochemical oxygen demand, may also reduce metal concentrations although meeting possible requirements for the removal of copper my be challenging