Coherent Signal Amplification in Bistable Nanomechanical Oscillators by Stochastic Resonance

Stochastic resonance is a counter-intuitive concept[1,2], ; the addition of noise to a noisy system induces coherent amplification of its response. First suggested as a mechanism for the cyclic recurrence of ice ages, stochastic resonance has been seen in a wide variety of macroscopic physical systems: bistable ring lasers[3], SQUIDs[4,5], magnetoelastic ribbons[6], and neurophysiological systems such as the receptors in crickets[7] and crayfish[8]. Although it is fundamentally important as a mechanism of coherent signal amplification, stochastic resonance is yet to be observed in nanoscale systems. Here we report the observation of stochastic resonance in bistable nanomechanical silicon oscillators, which can play an important role in the realization of controllable high-speed nanomechanical memory cells. Our nanomechanical systems were excited into a dynamic bistable state and modulated in order to induce controllable switching; the addition of white noise showed a marked amplification of the signal strength. Stochastic resonance in nanomechanical systems paves the way for exploring macroscopic quantum coherence and tunneling, and controlling nanoscale quantum systems for their eventual use as robust quantum logic devices.Comment: 18 pages, 4 figure

Proteomic Candidate Biomarkers of Drug-Induced Nephrotoxicity in the Rat

Improved biomarkers of acute nephrotoxicity are coveted by the drug development industry, regulatory agencies, and clinicians. In an effort to identify such biomarkers, urinary peptide profiles of rats treated with two different nephrotoxins were investigated. 493 marker candidates were defined that showed a significant response to cis-platin comparing a cis-platin treated cohort to controls. Next, urine samples from rats that received three consecutive daily doses of 150 or 300 mg/kg gentamicin were examined. 557 potential biomarkers were initially identified; 108 of these gentamicin-response markers showed a clear temporal response to treatment. 39 of the cisplatin-response markers also displayed a clear response to gentamicin. Of the combined 147 peptides, 101 were similarly regulated by gentamicin or cis-platin and 54 could be identified by tandem mass spectrometry. Most were collagen type I and type III fragments up-regulated in response to gentamicin treatment. Based on these peptides, classification models were generated and validated in a longitudinal study. In agreement with histopathology, the observed changes in classification scores were transient, initiated after the first dose, and generally persistent over a period of 10–20 days before returning to control levels. The data support the hypothesis that gentamicin-induced renal toxicity up-regulates protease activity, resulting in an increase in several specific urinary collagen fragments. Urinary proteomic biomarkers identified here, especially those common to both nephrotoxins, may serve as a valuable tool to investigate potential new drug candidates for the risk of nephrotoxicity

Electrocatalytic performance of SiO2-SWCNT nanocomposites prepared by electroassisted deposition

“The final publication is available at Springer via http://dx.doi.org/10.1007/s12678-013-0144-3”Composite materials made of porous SiO2 matrices filled with single-walled carbon nanotubes (SWCNTs) were deposited on electrodes by an electroassisted deposition method. The synthesized materials were characterized by several techniques, showing that porous silica prevents the aggregation of SWCNT on the electrodes, as could be observed by transmission electron microscopy and Raman spectroscopy. Different redox probes were employed to test their electrochemical sensing properties. The silica layer allows the permeation of the redox probes to the electrode surface and improves the electrochemical reversibility indicating an electrocatalytic effect by the incorporation of dispersed SWCNT into the silica films.This work was financed by the following research projects: MAT2010-15273 of the Spanish Ministerio de Economia y Competitividad and FEDER, PROMETEO/2013/038 of the GV, and CIVP16A1821 of the Fundacion Ramon Areces. Alonso Gamero-Quijano and David Salinas-Torres acknowledge Generalitat Valenciana (Santiago Grisolia Program) and Ministerio de Economia y Competitividad, respectively, for the funding of their research fellowships.Gamero-Quijano, A.; Huerta, F.; Salinas-Torres, D.; Morallón, E.; Montilla, F. (2013). Electrocatalytic performance of SiO2-SWCNT nanocomposites prepared by electroassisted deposition. Electrocatalysis. 4(4):259-266. https://doi.org/10.1007/s12678-013-0144-3S25926644P. Alivisatos, Nat. Biotechnol. 22, 47 (2004)S. Stankovich, D.A. Dikin, G.H. Dommett, K.M. Kohlhaas, E.J. Zimney, E.A. Stach, R.D. Piner, S.T. Nguyen, R.S. Ruoff, Nature 442, 282 (2006)D.W. Schaefer, R.S. Justice, Macromolecules 40, 8501 (2007)M. Endo, M.S. Strano, P.M. Ajayan, Carbon Nanotubes 111, 13 (2008)C.E. Banks, R.G. Compton, Analyst 131, 15 (2006)R.H. Baughman, A.A. Zakhidov, W.A. de Heer, Science 297, 787 (2002)Y.H. Lin, F. Lu, Y. Tu, Z.F. Ren, Nano Letters 4, 191 (2004)B.R. Azamian, J.J. Davis, K.S. Coleman, C.B. Bagshaw, M.L.H. Green, J. Am. Chem. Soc. 124, 12664 (2002)W. Yang, K. Ratinac, S. Ringer, P. Thordarson, J.G. Gooding, F. Braet, Angew. Chem. Int. Ed. 49, 2114 (2010)C.E. Banks, R.G. Compton, Analyst 130, 1232 (2005)L. Mazurenko, M. Etienne, O. Tananaiko, V. Zaitsev, A. Walcarius, Electrochim. Acta 83, 359 (2012)J.M.P. Paloma Yáñez-Sedeño, J. Riu, F.X. Rius, TrAC Trends in Analytical Chemistry 29, 939 (2010)Z.J. Wang, M. Etienne, S. Poller, W. Schuhmann, G.W. Kohring, V. Mamane, A. Walcarius, Electroanalysis 24, 376 (2012)R. Bandyopadhyaya, E. Nativ-Roth, O. Regev, R. Yerushalmi-Rozen, Nano Letters 2, 25 (2002)C. Park, Z. Ounaies, K.A. Watson, R.E. Crooks, J. Smith, S.E. Lowther, J.W. Connell, E.J. Siochi, J.S. Harrison, T.L.S. Clair, Chem. Phys. Lett. 364, 303 (2002)O. Matarredona, H. Rhoads, Z.R. Li, J.H. Harwell, L. Balzano, D.E. Resasco, Journal of Physical Chemistry B 107, 13357 (2003)L. Vaisman, H. Wagner, G. Marom, Advances in Colloid and Interface Science 128, 37 (2006)Y.C. Xing, Journal of Physical Chemistry B 108, 19255 (2004)J.J. Liang, Y. Huang, L. Zhang, Y. Wang, Y.F. Ma, T.Y. Guo, Y.S. Chen, Adv. Funct. Mater. 19, 2297 (2009)D. Salinas-Torres, F. Huerta, F. Montilla, E. Morallón, Electrochim. Acta 56, 2464 (2011)Z.F. Ren, Z.P. Huang, J.W. Xu, J.H. Wang, P. Bush, M.P. Siegal, P.N. Provencio, Science 282, 1105 (1998)W.Z. Li, S.S. Xie, L.X. Qian, B.H. Chang, B.S. Zou, W.Y. Zhou, R.A. Zhao, G. Wang, Science 274, 1701 (1996)M. Terrones, N. Grobert, J. Olivares, J.P. Zhang, H. Terrones, K. Kordatos, W.K. Hsu, J.P. Hare, P.D. Townsend, K. Prassides, A.K. Cheetham, H.W. Kroto, D.R.M. Walton, Nature 388, 52 (1997)R. Toledano, D. Mandler, Chem. Mater. 22, 3943 (2010)J.H. Rouse, Langmuir 21, 1055 (2005)X.B. Yan, B.K. Tay, Y. Yang, Journal of Physical Chemistry B 110, 25844 (2006)J. Lim, P. Malati, F. Bonet, B. Dunn, J. Electrochem. Soc. 154, A140 (2007)L.D. Zhu, C.Y. Tian, J.L. Zhai, R.L. Yang, Sensors and Actuators B-Chemical 125, 254 (2007)F. Montilla, M.A. Cotarelo, E. Morallón, J. Mater. Chem. 19, 305 (2009)D. Salinas-Torres, F. Montilla, F. Huerta, E. Morallón, Electrochim. Acta 56, 3620 (2011)T. Dobbins, R. Chevious, Y. Lvov, Polymers 3, 942 (2011)R. Esquembre, J.A. Poveda, C.R. Mateo, Journal of Physical Chemistry B 113, 7534 (2009)M.L. Ferrer, R. Esquembre, I. Ortega, C.R. Mateo, F. del Monte, Chem. Mater. 18, 554 (2006)M.J. O'Connell, S. Sivaram, S.K. Doorn, Physical Review B 69, 235415 (2004)C. Domingo, G. Santoro, Opt. Pura Apl 40, 175 (2007)M.S. Dresselhaus, G. Dresselhaus, R. Saito, A. Jorio, Physics Reports 409, 47 (2005)R.L. McCreery, Chem. Rev. 108, 2646 (2008)C.G. Zoski, in Handbook of Electrochemistry, 1st ed (Elsevier, Amsterdam, 2007

Sedentary behaviour is associated with increased long-term cardiovascular risk in patients with rheumatoid arthritis independently of moderate-to-vigorous physical activity

Background Rheumatoid Arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD). The physical dysfunction symptomatic of RA means people living with this disease spend large periods of the day sedentary, which may further elevate their risk of CVD. The primary aim of this study was to investigate relationships between objectively assessed sedentary behaviour patterns and light physical activity (LPA) with 10-year risk of CVD. Secondary aims were to explore the role of sedentary behaviour patterns and LPA for individual CVD risk factors and functional disability in RA. The extent to which associations were independent of moderate-to-vigorous physical activity (MVPA) engagement was also examined. Methods Baseline data from a subsample of participants recruited to the Physical Activity in Rheumatoid Arthritis (PARA) study were used to answer current research questions. Sixty-one patients with RA (mean age (± SD) = 54.92 ± 12.39 years) provided a fasted blood sample and underwent physical assessments to evaluate factors associated with their cardiovascular health. Sedentary behaviour patterns (sedentary time, sedentary bouts, sedentary breaks), LPA and MVPA were measured via 7-days of accelerometry. Ten-year CVD risk was computed (Q-risk-score2), and functional disability determined via questionnaire. Results Regressions revealed significant positive associations between sedentary time and the number of sedentary bouts per day ≥20 min with 10-year CVD risk, with the reverse true for LPA participation. Associations were independent of MVPA engagement. Conclusions Promoting LPA participation and restricting sedentary bouts to <20 min may attenuate long-term CVD risk in RA, independent of MVPA engagement

Small molecule sensitization to TRAIL is mediated via nuclear localization, phosphorylation and inhibition of chaperone activity of Hsp27

10.1038/cddis.2013.413Cell Death and Disease410

Patterns of Loss and Regeneration of Tropical Dry Forest in Madagascar: The Social Institutional Context

Loss of tropical forests and changes in land-use/land-cover are of growing concern worldwide. Although knowledge exists about the institutional context in which tropical forest loss is embedded, little is known about the role of social institutions in influencing regeneration of tropical forests. In the present study we used Landsat images from southern Madagascar from three different years (1984, 1993 and 2000) and covering 5500 km(2), and made a time-series analysis of three distinct large-scale patterns: 1) loss of forest cover, 2) increased forest cover, and 3) stable forest cover. Institutional characteristics underlying these three patterns were analyzed, testing the hypothesis that forest cover change is a function of strength and enforcement of local social institutions. The results showed a minor decrease of 7% total forest cover in the study area during the whole period 1984–2000, but an overall net increase of 4% during the period 1993–2000. The highest loss of forest cover occurred in a low human population density area with long distances to markets, while a stable forest cover occurred in the area with highest population density and good market access. Analyses of institutions revealed that loss of forest cover occurred mainly in areas characterized by insecure property rights, while areas with well-defined property rights showed either regenerating or stable forest cover. The results thus corroborate our hypothesis. The large-scale spontaneous regeneration dominated by native endemic species appears to be a result of a combination of changes in precipitation, migration and decreased human population and livestock grazing pressure, but under conditions of maintained and well-defined property rights. Our study emphasizes the large capacity of a semi-arid system to spontaneously regenerate, triggered by decreased pressures, but where existing social institutions mitigate other drivers of deforestation and alternative land-use

Linking Hydrothermal Geochemistry to Organismal Physiology: Physiological Versatility in Riftia pachyptila from Sedimented and Basalt-hosted Vents

Much of what is known regarding Riftia pachyptila physiology is based on the wealth of studies of tubeworms living at diffuse flows along the fast-spreading, basalt-hosted East Pacific Rise (EPR). These studies have collectively suggested that Riftia pachyptila and its chemoautotrophic symbionts are physiologically specialized, highly productive associations relying on hydrogen sulfide and oxygen to generate energy for carbon fixation, and the symbiont's nitrate reduction to ammonia for energy and biosynthesis. However, Riftia also flourish in sediment-hosted vents, which are markedly different in geochemistry than basalt-hosted systems. Here we present data from shipboard physiological studies and global quantitative proteomic analyses of Riftia pachyptila trophosome tissue recovered from tubeworms residing in the EPR and the Guaymas basin, a sedimented, hydrothermal vent field. We observed marked differences in symbiont nitrogen metabolism in both the respirometric and proteomic data. The proteomic data further suggest that Riftia associations in Guaymas may utilize different sulfur compounds for energy generation, may have an increased capacity for energy storage, and may play a role in degrading exogenous organic carbon. Together these data reveal that Riftia symbionts are far more physiologically plastic than previously considered, and that -contrary to previous assertions- Riftia do assimilate reduced nitrogen in some habitats. These observations raise new hypotheses regarding adaptations to the geochemical diversity of habitats occupied by Riftia, and the degree to which the environment influences symbiont physiology and evolution

Links Between Hydrothermal Environments, Pyrophosphate, Na+, and Early Evolution

The discovery that photosynthetic bacterial membrane-bound inorganic pyrophosphatase (PPase) catalyzed light-induced phosphorylation of orthophosphate (Pi) to pyrophosphate (PPi) and the capability of PPi to drive energy requiring dark reactions supported PPi as a possible early alternative to ATP. Like the proton-pumping ATPase, the corresponding membrane-bound PPase also is a H+-pump, and like the Na+-pumping ATPase, it can be a Na+-pump, both in archaeal and bacterial membranes. We suggest that PPi and Na+ transport preceded ATP and H+ transport in association with geochemistry of the Earth at the time of the origin and early evolution of life. Life may have started in connection with early plate tectonic processes coupled to alkaline hydrothermal activity. A hydrothermal environment in which Na+ is abundant exists in sediment-starved subduction zones, like the Mariana forearc in the W Pacific Ocean. It is considered to mimic the Archean Earth. The forearc pore fluids have a pH up to 12.6, a Na+-concentration of 0.7 mol/kg seawater. PPi could have been formed during early subduction of oceanic lithosphere by dehydration of protonated orthophosphates. A key to PPi formation in these geological environments is a low local activity of water

The spatial structure of lithic landscapes : the late holocene record of east-central Argentina as a case study

Fil: Barrientos, Gustavo. División Antropología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Catella, Luciana. División Arqueología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Oliva, Fernando. Centro Estudios Arqueológicos Regionales. Facultad de Humanidades y Artes. Universidad Nacional de Rosario; Argentin

Host Iron Binding Proteins Acting as Niche Indicators for Neisseria meningitidis

Neisseria meningitidis requires iron, and in the absence of iron alters its gene expression to increase iron acquisition and to make the best use of the iron it has. During different stages of colonization and infection available iron sources differ, particularly the host iron-binding proteins haemoglobin, transferrin, and lactoferrin. This study compared the transcriptional responses of N. meningitidis, when grown in the presence of these iron donors and ferric iron, using microarrays