Dynamics of an inchworm nano-walker

An inchworm processive mechanism is proposed to explain the motion of dimeric molecular motors such as kinesin. We present here preliminary results for this mechanism focusing on observables like mean velocity, coupling ratio and efficiency versus ATP concentration and the external load F.Comment: 6 pages, 2 figure

Multidisciplinary teaching of Biotechnology and Omics sciences

In the last years, there was a great boom in the Omics fields that have developed as multidisciplinary sciences. They use laboratory techniques related to Biology and Chemistry but also Bioinformatics tools. However, the developmental progress of these disciplines has led that much of undergraduate studies related to Biology have curricula that become outdated. From this point of view, it is necessary to focus the students to the fundamentals and techniques of complementary disciplines that will be essentials for the understanding of the Omics sciences. In the present work, we have developed a new teaching approach for Biochemistry, Biology and Bioinformatics students. They formed interdisciplinary working groups. These groups have prepared and presented communications about different techniques or methods in Molecular Biology, Omics or Bioinformatics participating in a technical meeting. This learning strategy “I do and I learn” has enabled to the students a first contact with the scientific communication including the approach to the scientific literature to acquire technical knowledge. The cooperation between students from different disciplines has enriched their point of view and even has been used in some practical master’s works.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The Origin And Loss Of Periodic Patterning In The Turtle Shell

The origin of the turtle shell over 200 million years ago greatly modified the amniote body plan, and the morphological plasticity of the shell has promoted the adaptive radiation of turtles. The shell, comprising a dorsal carapace and a ventral plastron, is a layered structure formed by basal endochondral axial skeletal elements (ribs, vertebrae) and plates of bone, which are overlain by keratinous ectodermal scutes. Studies of turtle development have mostly focused on the bones of the shell; however, the genetic regulation of the epidermal scutes has not been investigated. Here, we show that scutes develop from an array of patterned placodes and that these placodes are absent from a soft-shelled turtle in which scutes were lost secondarily. Experimentally inhibiting Shh, Bmp or Fgf signaling results in the disruption of the placodal pattern. Finally, a computational model is used to show how two coupled reaction-diffusion systems reproduce both natural and abnormal variation in turtle scutes. Taken together, these placodal signaling centers are likely to represent developmental modules that are responsible for the evolution of scutes in turtles, and the regulation of these centers has allowed for the diversification of the turtle shell

The Feynman effective classical potential in the Schr\"odinger formulation

New physical insight into the correspondence between path integral concepts and the Schr\"odinger formulation is gained by the analysis of the effective classical potential, that is defined within the Feynman path integral formulation of statistical mechanics. This potential is related to the quasi-static response of the equilibrium system to an external force. These findings allow for a comprehensive formulation of dynamical approximations based on this potential.Comment: 10 pages, 4 figure

Role of Caveolin 1, E-Cadherin, Enolase 2 and PKCalpha on resistance to methotrexate in human HT29 colon cancer cells

<p>Abstract</p> <p>Background</p> <p>Methotrexate is one of the earliest cytotoxic drugs used in cancer therapy, and despite the isolation of multiple other folate antagonists, methotrexate maintains its significant role as a treatment for different types of cancer and other disorders. The usefulness of treatment with methotrexate is limited by the development of drug resistance, which may be acquired through different ways. To get insights into the mechanisms associated with drug resistance and sensitization we performed a functional analysis of genes deregulated in methotrexate resistant cells, either due to its co-amplification with the <it>dhfr </it>gene or as a result of a transcriptome screening using microarrays.</p> <p>Methods</p> <p>Gene expression levels were compared between triplicate samples from either HT29 sensitive cells and resistant to 10^-5M MTX by hybridization to the GeneChip^®HG U133 PLUS 2.0 from Affymetrix. After normalization, a list of 3-fold differentially expressed genes with a p-value < 0.05 including multiple testing correction (Benjamini and Hochberg false discovery rate) was generated. RT-Real-time PCR was used to validate the expression levels of selected genes and copy-number was determined by qPCR. Functional validations were performed either by siRNAs or by transfection of an expression plasmid.</p> <p>Results</p> <p>Genes adjacent to the <it>dhfr locus </it>and included in the 5q14 amplicon were overexpressed in HT29 MTX-resistant cells. Treatment with siRNAs against those genes caused a slight reduction in cell viability in both HT29 sensitive and resistant cells. On the other hand, microarray analysis of HT29 and HT29 MTX resistant cells unveiled overexpression of caveolin 1, enolase 2 and PKCα genes in resistant cells without concomitant copy number gain. siRNAs against these three genes effectively reduced cell viability and caused a decreased MTX resistance capacity. Moreover, overexpression of E-cadherin, which was found underexpressed in MTX-resistant cells, also sensitized the cells toward the chemotherapeutic agent. Combined treatments targeting siRNA inhibition of caveolin 1 and overexpression of E-cadherin markedly reduced cell viability in both sensitive and MTX-resistant HT29 cells.</p> <p>Conclusion</p> <p>We provide functional evidences indicating that caveolin 1 and E-cadherin, deregulated in MTX resistant cells, may play a critical role in cell survival and may constitute potential targets for coadjuvant therapy.</p

Core losses analysis of the LCL filter inductor for SiC-based inverter

The ability of SiC devices to switch at high speed allows increasing significantly the power density in both converters and passive components, reducing their required size. To mitigate harmonic injection form inverters into the grid, in order to comply with power quality standards, an accurate filter design is required. Given its excellent performance, an LCL filter is the configuration most suitable in grid-connected power converters. Several parameters must be considered when designing an effective LCL filter, and the inverter-side inductor assumes a special importance because of its relevance to suppress high frequency harmonic content at the inverter side. One of the most relevant issues to be considered in the process of designing the LCL filter is the evaluation of core losses in the inverter-side inductor, which will determine the final temperature of the inductor. This paper analyses the core losses of the inverter-side inductor of an LCL filter. The proposed method is based on the computation of the current harmonics generated by the inverter and on Steinmetz’s empirical equation. As a result, core losses calculated taking into account several carrier and sideband harmonics show good agreement with the experimental values. When current harmonics are estimated by simulation, as it is done in the proposed design procedure, results are less accurate, but precise enough for a design procedure

MoDeST: a compositional modeling formalism for hard and softly timed systems

This paper presents Modest (MOdeling and DEscription language for Stochastic Timed systems), a formalism that is aimed to support (i) the modular description of reactive system's behaviour while covering both (ii) functional and (iii) nonfunctional system aspects such as timing and quality-of-service constraints in a single specification. The language contains features such as simple and structured data types, structuring mechanisms like parallel composition and abstraction, means to control the granularity of assignments, exception handling, and non-deterministic and random branching and timing. Modest can be viewed as an overarching notation for a wide spectrum of models, ranging from labeled transition systems, to timed automata (and probabilistic variants thereof) as well as prominent stochastic processes such as (generalized semi-)Markov chains and decision processes. The paper describes the design rationales and details of the syntax and semantics