549 research outputs found

    Magnetophoretic circuits for digital control of single particles and cells.

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    The ability to manipulate small fluid droplets, colloidal particles and single cells with the precision and parallelization of modern-day computer hardware has profound applications for biochemical detection, gene sequencing, chemical synthesis and highly parallel analysis of single cells. Drawing inspiration from general circuit theory and magnetic bubble technology, here we demonstrate a class of integrated circuits for executing sequential and parallel, timed operations on an ensemble of single particles and cells. The integrated circuits are constructed from lithographically defined, overlaid patterns of magnetic film and current lines. The magnetic patterns passively control particles similar to electrical conductors, diodes and capacitors. The current lines actively switch particles between different tracks similar to gated electrical transistors. When combined into arrays and driven by a rotating magnetic field clock, these integrated circuits have general multiplexing properties and enable the precise control of magnetizable objects

    Evidence of the late lignification of the G-layer in Simarouba tension wood, to assist understanding how non-G-layer species produce tensile stress

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    International audienceTo recover verticality after disturbance, angiosperm trees produce " tension wood " allowing them to bend actively. The driving force of the tension has been shown to take place in the G-layer, a specific unlignified layer of the cell wall observed in most temperate species. However, in tropical rain forests, the G-layer is often absent and the mechanism generating the forces to reorient trees remains unclear. A study was carried out on tilted seedlings, saplings and adult Simarouba amara trees – a species known to not produce a G-layer. Microscopic observations were done on sections of normal and tension wood after staining or observed under UV light to assess the presence/absence of lignin. We showed that S. amara produces a cell-wall layer with all of the characteristics typical of G-layers, but that this G-layer can be observed only as a temporary stage of the cell-wall development because it is masked by a late lignification. Being thin and lignified, tension wood fibres cannot be distinguished from normal wood fibres in the mature wood of adult trees. These observations indicate that the mechanism generating the high tensile stress in tension wood is likely to be the same as that in species with a typical G-layer and also in species where the G-layer cannot be observed in mature cells

    Covariant Poisson's equation in torsional Newton-Cartan gravity

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    We derive the covariant Poisson's equation of (d+1)-dimensional Newton-Cartan gravity with (twistless) torsion by applying the `non-relativistic conformal method' introduced in arXiv:1512.06277. We apply this method on-shell to a Schr\"odinger field theory on the curved Newton-Hooke background. The covariance of the field equation in the presence of the non-relativistic cosmological constant, entails fixing all coefficients in the covariant Poisson's equation for (twistless) torsional Newton-Cartan gravity. We further derive Ehlers conditions and an equation associated to the torsion in this method.Comment: 20 pages, v2 references adde

    Oxygen Diffusion Layer on Ti–6Al–4V Alloy: Scratch and Dry Wear Resistance

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    Ti–6Al–4V has prominent physical and mechanical properties, which nominate it for various engineering applications. A drawback of the alloy, however, is low scratch and wear resistance, which can be improved by a diffusion treatment. Oxygen diffusion layer (ODL) was produced on Ti–6Al–4V by thermal oxidation at a temperature of 850 °C for 3 and 6 h. Hardness of the samples was measured using a nano-indentation tester. Micro-scratch tests were performed under progressive and constant normal loads of 0–50 N. Dry wear behavior of the samples was studied using a ball-on-disk tribometer. The wear tests were carried out under various normal loads of 7.5, 15 and 30 N for sliding distances of 50, 100, 200 and 300 m using alumina balls as the counterface. The wear and scratch tracks were examined by scanning electron microscope and surface profilometer. The ODL samples showed higher hardness and lower plastic deformation as compared with Ti–6Al–4V. The brittle behavior of the ODL samples caused the formation of cracks and the development of large acoustic signals during scratching under normal loads of 40 and 50 N. The results also showed a higher scratch and wear resistance of the ODL samples compared with Ti–6Al–4V. However, the oxygen diffusion layer formed after 3 h of oxidation showed a sharp increase in the wear rate of the alloy under a normal load of 30 N and a sliding distance of 100 m

    Self-assembled amyloid fibrils with controllable conformational heterogeneity

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    Amyloid fibrils are a hallmark of neurodegenerative diseases and exhibit a conformational diversity that governs their pathological functions. Despite recent findings concerning the pathological role of their conformational diversity, the way in which the heterogeneous conformations of amyloid fibrils can be formed has remained elusive. Here, we show that microwave-assisted chemistry affects the self-assembly process of amyloid fibril formation, which results in their conformational heterogeneity. In particular, microwave-assisted chemistry allows for delicate control of the thermodynamics of the self-assembly process, which enabled us to tune the molecular structure of ??-lactoglobulin amyloid fibrils. The heterogeneous conformations of amyloid fibrils, which can be tuned with microwave-assisted chemistry, are attributed to the microwave-driven thermal energy affecting the electrostatic interaction during the self-assembly process. Our study demonstrates how microwave-assisted chemistry can be used to gain insight into the origin of conformational heterogeneity of amyloid fibrils as well as the design principles showing how the molecular structures of amyloid fibrils can be controlledopen0

    Regulation of apoptosis-inducing factor-mediated, cisplatin-induced apoptosis by Akt

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    Cisplatin is a first-line chemotherapeutic for ovarian cancer, although chemoresistance limits treatment success. Apoptosis, an important determinant of cisplatin sensitivity, occurs via caspase-dependent and -independent mechanisms. Activation of the protein kinase Akt, commonly observed in ovarian tumours, confers resistance to ovarian cancer cells via inhibition of caspase-dependent apoptosis. However, the effect of Akt on cisplatin-induced, caspase-independent apoptosis remains unclear. We show that in chemosensitive ovarian cancer cells, cisplatin induces the mitochondrial release and nuclear translocation of apoptosis-inducing factor (AIF), a mediator of caspase-independent apoptosis, and AIF-dependent apoptosis. Cisplatin failed to induce these effects in the chemoresistant variant cells. Overexpression of AIF sensitised resistant cells to cisplatin-induced apoptosis. Finally, activation of Akt attenuated the cisplatin-induced mitochondrial release and nuclear accumulation of AIF and apoptosis in chemosensitive cells, whereas inhibition of Akt activity facilitated these effects and sensitised chemoresistant cells to AIF-dependent, cisplatin-induced apoptosis. These results suggest that cisplatin-induced apoptosis proceeds, in part, via a caspase-independent mechanism involving AIF, and that Akt activation confers resistance to cisplatin-induced apoptosis by blocking this pathway. These results provide insights into the molecular mechanism of chemoresistance, and suggest that inhibition of Akt activity may represent a novel therapeutic approach to the treatment of cisplatin-resistant ovarian cancer

    First report on the percentiles of the glomerular filtration rate in iranian children using the 2009 schwartz equations

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    The glomerular filtration rate (GFR) is widely considered the best overall index of renal function. The Schwartz equations are designed for measuring the GFR in children between 1 and 16 years of age. In the present study, we investigated the percentiles of the GFR in a general population of Iranian children with no known renal disease via the 2009 Schwartz equations (updated and combined equations). Between 2010 and 2011, we selected 687 children aged 7�16 years from the Iranian province of Isfahan. Blood samples were analyzed for blood urea nitrogen, creatinine, and cystatin C. For each child, we calculated the GFR using 2 Schwartz equations. The Wilcoxon test was applied to examine the differences in the estimated GFRs between the equations. To determine the correlation between the GFRs obtained via the updated and combined Schwartz equations in the boys and the girls and also for the correlation between age and the GFR, we performed the Pearson or Spearman correlation coefficients. The statistical analyses were conducted using MedCalc, version 12.1.4.0 (MedCalc Software, Mariakerke, Belgium). The mean GFR was 100.06±19.80 mL/min/1.73 m2 based on the updated equation and 96.10±18.44 mL/min/1.73 m2 according to the combined equation. No significant differences were observed between these equations in estimating the GFRs. The correlation analysis for determining the association between age and the GFR estimated by the updated (r=0.05, P=0.1) and combined (r=0.06, P=0.09) Schwartz equations was not statistically significant. In conclusion, in the current study we showed that the updated and combined Schwartz equations exhibited high concordance in estimating GFR values in this age group. © 2018, Shiraz University of Medical Sciences. All rights reserved

    Bone mineral density is lower in male than female patients with plaque-type psoriasis in Iran

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    Background There are many similarities with regard to contributing cytokines in patients with psoriasis and osteoporosis. A theory of probable relationship between these two entities has been proposed but there is no concordant consensus. The aim of this study was to evaluate bone mineral density (BMD) in patients with psoriasis. Method and materials This cross-sectional study of BMD was conducted with 64 eligible patients with psoriasis who were referred to the dermatology clinic of Razi hospital in Tehran, Iran in between 2011 and 2012. Results The mean T score of femoral neck was �1.17 and �0.49 in men and women, respectively, which was statistically significant (p =.047). The mean T score of the lumbar spine was �0.93 and �0.30 in men and women, respectively, but not statistically significant (p =.058). In total except with the exclusion of the study site (femur or lumbar), men and women did not have a statistically significant difference with regard to osteoporosis or osteopenia in BMD (p =.114). The Pearson correlation coefficient demonstrated a moderate inverse relationship between age and T score of the femoral neck and lumbar spine (r = �0.419 and �.406, respectively), which was statistically significant (p =.001). Although there was no statistically significant relationship between the Psoriasis Area and Severity Index (PASI) and T scores of the femoral neck (p =.596), a positive and weak correlation was observed between the PASI and T scores for the lumbar spine, which was statistically significant (r = 0.269; p =.03). Conclusion Patients with psoriasis had decreased bone density, which was more significant in men. Prevalence of osteoporosis showed no statistically significant difference when compared with the healthy population in Iran. © 201

    Bone mineral density is lower in male than female patients with plaque-type psoriasis in Iran

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    Background There are many similarities with regard to contributing cytokines in patients with psoriasis and osteoporosis. A theory of probable relationship between these two entities has been proposed but there is no concordant consensus. The aim of this study was to evaluate bone mineral density (BMD) in patients with psoriasis. Method and materials This cross-sectional study of BMD was conducted with 64 eligible patients with psoriasis who were referred to the dermatology clinic of Razi hospital in Tehran, Iran in between 2011 and 2012. Results The mean T score of femoral neck was �1.17 and �0.49 in men and women, respectively, which was statistically significant (p =.047). The mean T score of the lumbar spine was �0.93 and �0.30 in men and women, respectively, but not statistically significant (p =.058). In total except with the exclusion of the study site (femur or lumbar), men and women did not have a statistically significant difference with regard to osteoporosis or osteopenia in BMD (p =.114). The Pearson correlation coefficient demonstrated a moderate inverse relationship between age and T score of the femoral neck and lumbar spine (r = �0.419 and �.406, respectively), which was statistically significant (p =.001). Although there was no statistically significant relationship between the Psoriasis Area and Severity Index (PASI) and T scores of the femoral neck (p =.596), a positive and weak correlation was observed between the PASI and T scores for the lumbar spine, which was statistically significant (r = 0.269; p =.03). Conclusion Patients with psoriasis had decreased bone density, which was more significant in men. Prevalence of osteoporosis showed no statistically significant difference when compared with the healthy population in Iran. © 201

    Lessons learned from the introduction of autonomous monitoring to the EUVE science operations center

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    The University of California at Berkeley's (UCB) Center for Extreme Ultraviolet Astrophysics (CEA), in conjunction with NASA's Ames Research Center (ARC), has implemented an autonomous monitoring system in the Extreme Ultraviolet Explorer (EUVE) science operations center (ESOC). The implementation was driven by a need to reduce operations costs and has allowed the ESOC to move from continuous, three-shift, human-tended monitoring of the science payload to a one-shift operation in which the off shifts are monitored by an autonomous anomaly detection system. This system includes Eworks, an artificial intelligence (AI) payload telemetry monitoring package based on RTworks, and Epage, an automatic paging system to notify ESOC personnel of detected anomalies. In this age of shrinking NASA budgets, the lessons learned on the EUVE project are useful to other NASA missions looking for ways to reduce their operations budgets. The process of knowledge capture, from the payload controllers for implementation in an expert system, is directly applicable to any mission considering a transition to autonomous monitoring in their control center. The collaboration with ARC demonstrates how a project with limited programming resources can expand the breadth of its goals without incurring the high cost of hiring additional, dedicated programmers. This dispersal of expertise across NASA centers allows future missions to easily access experts for collaborative efforts of their own. Even the criterion used to choose an expert system has widespread impacts on the implementation, including the completion time and the final cost. In this paper we discuss, from inception to completion, the areas where our experiences in moving from three shifts to one shift may offer insights for other NASA missions
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