Autonomous Motility of Active Filaments due to Spontaneous Flow-Symmetry Breaking

We simulate the nonlocal Stokesian hydrodynamics of an elastic filament which is active due a permanent distribution of stresslets along its contour. A bending instability of an initially straight filament spontaneously breaks flow symmetry and leads to autonomous filament motion which, depending on conformational symmetry, can be translational or rotational. At high ratios of activity to elasticity, the linear instability develops into nonlinear fluctuating states with large amplitude deformations. The dynamics of these states can be qualitatively understood as a superposition of translational and rotational motion associated with filament conformational modes of opposite symmetry. Our results can be tested in molecular-motor filament mixtures, synthetic chains of autocatalytic particles, or other linearly connected systems where chemical energy is converted to mechanical energy in a fluid environment.Comment: 7 pages, 3 figures; contains supplemental text; movies at http://proofideas.org/rjoy/gallery; published in Physical Review Letter

Sigma-2: Multiple sequence alignment of non-coding DNA via an evolutionary model

<p>Abstract</p> <p>Background</p> <p>While most multiple sequence alignment programs expect that all or most of their input is known to be homologous, and penalise insertions and deletions, this is not a reasonable assumption for non-coding DNA, which is much less strongly conserved than protein-coding genes. Arguing that the goal of sequence alignment should be the detection of <it>homology </it>and not <it>similarity</it>, we incorporate an evolutionary model into a previously published multiple sequence alignment program for non-coding DNA, Sigma, as a sensitive likelihood-based way to assess the significance of alignments. Version 1 of Sigma was successful in eliminating spurious alignments but exhibited relatively poor sensitivity on synthetic data. Sigma 1 used a <it>p</it>-value (the probability under the "null hypothesis" of non-homology) to assess the significance of alignments, and, optionally, a background model that captured short-range genomic correlations. Sigma version 2, described here, retains these features, but calculates the <it>p</it>-value using a sophisticated evolutionary model that we describe here, and also allows for a transition matrix for different substitution rates from and to different nucleotides. Our evolutionary model takes separate account of mutation and fixation, and can be extended to allow for locally differing functional constraints on sequence.</p> <p>Results</p> <p>We demonstrate that, on real and synthetic data, Sigma-2 significantly outperforms other programs in specificity to genuine homology (that is, it minimises alignment of spuriously similar regions that do not have a common ancestry) while it is now as sensitive as the best current programs.</p> <p>Conclusions</p> <p>Comparing these results with an extrapolation of the best results from other available programs, we suggest that conservation rates in intergenic DNA are often significantly over-estimated. It is increasingly important to align non-coding DNA correctly, in regulatory genomics and in the context of whole-genome alignment, and Sigma-2 is an important step in that direction.</p

Reactive thymic hyperplasia mimicking relapse in a child with post-treatment T-cell Non-Hodgkin's lymphoma: A case report and literature review

Background: Chemotherapy usually results in the premature shrinkage of thymic cells, often resulting in atrophy. However, in some children, the thymus has the potential to regenerate following the withdrawal of stimulus, resulting in an increase in thymic cells – called rebound/reactive thymic hyperplasia. This phenomenon often appears clinically and radiologically similar to lymphoma in the anterior mediastinum, leading to overtreatment. Case report: We report a 6-year-old boy with T-Lymphoblastic lymphoma (LL) who presented with mediastinal mass. He was treated with high risk ALL protocol and completed treatment uneventfully. Post-treatment PET-CT for routine assessment showed an anterior mediastinal mass with a SUVt of 4.64, highly suggestive of recurrence, however was finally diagnosed with thymic hyperplasia confirmed by biopsy. Conclusion: Pediatric hemato-oncologists and radiologists need to be aware of this phenomenon to avoid misdiagnosis and overtreatment. Relapse should always be confirmed by histopathological examination

Deciphering the Role of MicroRNAs in Neuroblastoma

Neuroblastoma (NB) is a type of peripheral sympathetic nervous system cancer that most commonly affects children. It is caused by the improper differentiation of primitive neural crest cells during embryonic development. Although NB occurs for 8% of paediatric cancers, it accounts for 15% of cancer-related deaths. Despite a considerable increase in cytotoxic chemo- and radiotherapy, patients in advanced stages remain virtually incurable. Therefore, there is a desperate necessity for new treatment strategies to be investigated. Accumulating evidence suggested that microRNAs (miRNAs) are a class of non-coding RNAs with 19&ndash;25 nucleotides lengths and play a central role in the development of NB carcinogenesis. Fascinatingly, miRNA inhibitors have an antisense property that can inhibit miRNA function and suppress the activity of mature miRNA. However, many studies have addressed miRNA inhibition in the treatment of NB, but their molecular mechanisms and signalling pathways are yet to be analysed. In this study, we impart the current state of knowledge about the role of miRNA inhibition in the aetiology of NB

Biowaste-Derived Interconnected Carbon Nanosheet-Supported Iron as a Highly Stable and Excellent Electrocatalyst for Overall Water Splitting

Water splitting needs low-cost materials that can efficiently catalyze both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). We prepared biowaste-derived self-nitrogen-doped interconnected hierarchically porous carbon nanosheet Fe@PSAC as a bifunctional and ultradurable electrocatalyst for water splitting. Fe@PSAC exhibits a low overpotential of 118 mV (84 mV/dec) for HER and 231 mV (66 mV/dec) for OER @ 10 mA/cm2 in 1.0 M KOH (without iR correction). Fe@PSAC exhibits durability for 100 h with minimum potential losses of 2.9 and 2.3% for HER and OER, respectively. The turnover frequency of Fe@PSAC (0.2297/s) and IrO2 (0.0231/s) for OER and Fe@PSAC (0.0784/s) and Pt/C (0.1806/s) for HER was nearer to Pt/C and greater than IrO2, respectively. The synergy between self-nitrogen-doped interconnected hierarchically porous carbon nanosheets and iron endows excellent bifunctional activity and stability. The Fe@PSAC//Fe@PSAC water electrolyzer exhibits excellent activity at 1.58 V to reach 10 mA/cm2 with high stability for 120 h with a 3.2% potential loss. The Fe@PSAC//Fe@PSAC electrocatalyst shows an exceptional activity of 1.58 V using solar-assisted water electrolysis. The Fe@PSAC//Fe@PSAC electrode has been strongly recommended for low-cost hydrogen fuel production on a large scale