Factorization and Lie point symmetries of general Lienard-type equation in the complex plane

We present a variational approach to a general Lienard-type equation in order to linearize it and, as an example, the Van der Pol oscillator is discussed. The new equation which is almost linear is factorized. The point symmetries of the deformed equation are also discussed and the two-dimensional Lie algebraic generators are obtained

Phylogenetic congruence of Plasmodium spp. and wild ungulate hosts in the Peruvian Amazon

Malaria parasites are known to infect a variety of vertebrate hosts, including ungulates. However, ungulates of Amazonia have not been investigated. We report for the first time, the presence of parasite lineages closely related to Plasmodium odocoilei clade 1 and clade 2 in free-ranging South American red-brocket deer (Mazama americana; 44.4%, 4/9) and gray-brocket deer (Mazama nemorivaga; 50.0%, 1/2). We performed PCR-based analysis of blood samples from 47 ungulates of five different species collected during subsistence hunting by an indigenous community in the Peruvian Amazon. We detected Plasmodium malariae/brasilianum lineage in a sample from red-brocket deer. However, no parasite DNA was detected in collared peccary (Pecari tajacu; 0.0%, 0/10), white-lipped peccary (Tayassu pecari; 0.0%, 0/15), and tapir (Tapirus terrestris; 0.0%, 0/11). Concordant phylogenetic analyses suggested a possible co-evolutionary relationship between the Plasmodium lineages found in American deer and their hosts

Precision Electron-Beam Polarimetry using Compton Scattering at 1 GeV

We report on the highest precision yet achieved in the measurement of the polarization of a low energy, $\mathcal{O}$(1 GeV), electron beam, accomplished using a new polarimeter based on electron-photon scattering, in Hall~C at Jefferson Lab. A number of technical innovations were necessary, including a novel method for precise control of the laser polarization in a cavity and a novel diamond micro-strip detector which was able to capture most of the spectrum of scattered electrons. The data analysis technique exploited track finding, the high granularity of the detector and its large acceptance. The polarization of the $180~\mu$A, $1.16$~GeV electron beam was measured with a statistical precision of $<$~1\% per hour and a systematic uncertainty of 0.59\%. This exceeds the level of precision required by the \qweak experiment, a measurement of the vector weak charge of the proton. Proposed future low-energy experiments require polarization uncertainty $<$~0.4\%, and this result represents an important demonstration of that possibility. This measurement is also the first use of diamond detectors for particle tracking in an experiment.Comment: 9 pages, 7 figures, published in PR

Mass Changes of the Greenland and Antarctic Ice Sheets and Shelves and Contributions to Sea-level Rise: 1992-2002

Changes in ice mass are estimated from elevation changes derived from 10.5 years (Greenland) and 9 years (Antarctica) of satellite radar altimetry data from the European Remote-sensing Satellites ERS-1 and -2. For the first time, the dH/dt values are adjusted for changes in surface elevation resulting from temperature-driven variations in the rate of fun compaction. The Greenland ice sheet is thinning at the margins (-42 plus or minus 2 Gta(sup -1) below the equilibrium line altitude (ELA)) and growing inland (+53 plus or minus 2 Gt a(sup -1)above the ELA) with a small overall mass gain (+11 plus or minus 3 Gt a(sup -1); -0.03 mm a(sup -1) SLE (sea level equivalent)). The ice sheet in West Antarctica (WA) is losing mass (-47 (dot) 4 GT a(sup -1) and the ice sheet in East Antarctica (EA) shows a small mass gain (+16 plus or minus 11 Gt a(sup -1) for a combined net change of -31 plus or minus 12 Gt a(sup -1) (+0.08 mm a(sup -1) SLE)). The contribution of the three ice sheets to sea level is +0.05 plus or minus 0.03 mm a(sup -1). The Antarctic ice shelves show corresponding mass changes of -95 (dot) 11 Gt a(sup -1) in WA and +142 plus or minus 10 Gt a(sup -1) in EA. Thinning at the margins of the Greenland ice sheet and growth at higher elevations is an expected response to increasing temperatures and precipitation in a warming climate. The marked thinnings in the Pine Island and Thwaites Glacier basins of WA and the Totten Glacier basin in EA are probably ice-dynamic responses to long-term climate change and perhaps past removal of their adjacent ice shelves. The ice growth in the southern Antarctic Peninsula and parts of EA may be due to increasing precipitation during the last century

Greenland Ice Sheet Mass Balance: Distribution of Increased Mass Loss with Climate Warming; 2003-07 Versus 1992-2002

We derive mass changes of the Greenland ice sheet (GIS) for 2003-07 from ICESat laser altimetry and compare them with results for 1992-2002 from ERS radar and airborne laser altimetry. The GIS continued to grow inland and thin at the margins during 2003 07, but surface melting and accelerated flow significantly increased the marginal thinning compared with the 1990s. The net balance changed from a small loss of 7 plus or minus 3 Gt a 1(sup -1) in the 1990s to 171 plus or minus 4 Gt a (sup -1) for 2003-07, contributing 0.5 mm a(sup -1) to recent global sea-level rise. We divide the derived mass changes into two components: (1) from changes in melting and ice dynamics and (2) from changes in precipitation and accumulation rate. We use our firn compaction model to calculate the elevation changes driven by changes in both temperature and accumulation rate and to calculate the appropriate density to convert the accumulation-driven changes to mass changes. Increased losses from melting and ice dynamics (17-206 Gt a(sup-1) are over seven times larger than increased gains from precipitation (10 35 Gt a(sup-1) during a warming period of approximately 2 K (10 a)(sup -1) over the GIS. Above 2000m elevation, the rate of gain decreased from 44 to 28 Gt a(sup-1), while below 2000m the rate of loss increased from 51 to 198 Gt a(sup-1). Enhanced thinning below the equilibrium line on outlet glaciers indicates that increased melting has a significant impact on outlet glaciers, as well as accelerating ice flow. Increased thinning at higher elevations appears to be induced by dynamic coupling to thinning at the margins on decadal timescales

Removal allura red dye by bentonite and organobentonite

El método de adsorción de diversos contaminantes, empleando minerales arcillosos, es una de las técnicas más factibles de utilizar a la hora de la remediación de efluentes contaminados. La factibilidad del proceso radica principalmente en el bajo costo de los materiales adsorbentes, por ser abundantes en la naturaleza, y sus características naturales: reducido tamaño de partícula, capacidad de intercambio catiónico y elevada superficie específica. Sin embargo, aquellos efluentes contaminados con tintes coloreados orgánicos provenientes de diversas industrias (textil, alimenticia, plásticos, papel, entre otras) suelen no ser retenidos por las arcillas naturales debido a su naturaleza hidrofílica. Ésta problemática podría solucionarse si se realiza un tratamiento de intercambio de iones inorgánicos por orgánicos, que modifiquen las propiedades superficiales naturales de la arcilla, dando origen a lo que se conoce como organoarcilla. La remoción de tintes de naturaleza orgánica es una problemática que crece día a día debido a la falta de controles ambientales en las aguas de desechos, originadas por industrias cada vez más abundantes debido al creciente consumo de productos manufacturados (papel, plásticos, textiles, cueros, gomas, etc.). Los colorantes orgánicos usados para impartir color a los productos, tienen la particularidad de ser muy solubles en agua y, debido a que, generalmente, tienen estructuras aromáticas complejas, son biológicamente no degradables y presentan alta estabilidad y toxicidad, representando una inminente amenaza ambiental. Es por lo expuesto que el objetivo del presente trabajo es evaluar el empleo de una bentonita y una organobentonita, en la remoción del tinte orgánico Red Allura, por medio de ensayos de adsorción. Los sólidos adsorbentes y la solución coloreada a retener fueron estudiados empleando técnicas analíticas instrumentales de Difracción de Rayos X (DRX), Espectrometría Infrarroja (IR), Análisis Térmico Termogravimétrico (TG) y Espectrometría UV-visible. Se efectuaron experiencias de adsorción del colorante con una concentración inicial de 250mg.L-1, en sistema batch, a temperatura ambiente, durante 24 horas, variando las relaciones sólido/líquido; transcurrido éste tiempo se extrajeron alícuotas del sobrenadante para su cuantificación, recuperando los sólidos previa eliminación de la solución no retenida, mediante reiterados lavados con agua destilada. Los datos obtenidos indicarían una adsorción favorable del colorante en estudio por la organobentonita.Trabajo publicado en Maria dos Santos Alfonso y Rosa María Torres Sánchez (eds.). Enfoques Interdisciplinarios para la Sustentabilidad del Ambiente. Buenos Aires: Editorial Sociedad Argentina de Ciencia y Tecnología Ambiental, 2015.Centro de Investigación y Desarrollo en Ciencias AplicadasComisión de Investigaciones Científicas de la provincia de Buenos Aire

Removal allura red dye by bentonite and organobentonite

El método de adsorción de diversos contaminantes, empleando minerales arcillosos, es una de las técnicas más factibles de utilizar a la hora de la remediación de efluentes contaminados. La factibilidad del proceso radica principalmente en el bajo costo de los materiales adsorbentes, por ser abundantes en la naturaleza, y sus características naturales: reducido tamaño de partícula, capacidad de intercambio catiónico y elevada superficie específica. Sin embargo, aquellos efluentes contaminados con tintes coloreados orgánicos provenientes de diversas industrias (textil, alimenticia, plásticos, papel, entre otras) suelen no ser retenidos por las arcillas naturales debido a su naturaleza hidrofílica. Ésta problemática podría solucionarse si se realiza un tratamiento de intercambio de iones inorgánicos por orgánicos, que modifiquen las propiedades superficiales naturales de la arcilla, dando origen a lo que se conoce como organoarcilla. La remoción de tintes de naturaleza orgánica es una problemática que crece día a día debido a la falta de controles ambientales en las aguas de desechos, originadas por industrias cada vez más abundantes debido al creciente consumo de productos manufacturados (papel, plásticos, textiles, cueros, gomas, etc.). Los colorantes orgánicos usados para impartir color a los productos, tienen la particularidad de ser muy solubles en agua y, debido a que, generalmente, tienen estructuras aromáticas complejas, son biológicamente no degradables y presentan alta estabilidad y toxicidad, representando una inminente amenaza ambiental. Es por lo expuesto que el objetivo del presente trabajo es evaluar el empleo de una bentonita y una organobentonita, en la remoción del tinte orgánico Red Allura, por medio de ensayos de adsorción. Los sólidos adsorbentes y la solución coloreada a retener fueron estudiados empleando técnicas analíticas instrumentales de Difracción de Rayos X (DRX), Espectrometría Infrarroja (IR), Análisis Térmico Termogravimétrico (TG) y Espectrometría UV-visible. Se efectuaron experiencias de adsorción del colorante con una concentración inicial de 250mg.L-1, en sistema batch, a temperatura ambiente, durante 24 horas, variando las relaciones sólido/líquido; transcurrido éste tiempo se extrajeron alícuotas del sobrenadante para su cuantificación, recuperando los sólidos previa eliminación de la solución no retenida, mediante reiterados lavados con agua destilada. Los datos obtenidos indicarían una adsorción favorable del colorante en estudio por la organobentonita.Trabajo publicado en Maria dos Santos Alfonso y Rosa María Torres Sánchez (eds.). Enfoques Interdisciplinarios para la Sustentabilidad del Ambiente. Buenos Aires: Editorial Sociedad Argentina de Ciencia y Tecnología Ambiental, 2015.Centro de Investigación y Desarrollo en Ciencias AplicadasComisión de Investigaciones Científicas de la provincia de Buenos Aire

Tree recruitment in an empty forest

To assess how the decimation of large vertebrates by hunting alters recruitment processes in a tropical forest, we compared the sapling cohorts of two structurally and compositionally similar forests in the Rio Manu floodplain in southeastern Peru. Large vertebrates were severely depleted at one site, Boca Manu (BM), whereas the other, Cocha Cashu Biological Station (CC), supported an intact fauna. At both sites we sampled small (1 m tall, ,1 cm dbh) and large (1 cm and ,10 cm dbh) saplings in the central portion of 4-ha plots within which all trees 10 cm dbh were mapped and identified. This design ensured that all conspecific adults within at least 50 m (BM) or 55 m (CC) of any sapling would have known locations. We used the Janzen-Connell model to make five predictions about the sapling cohorts at BM with respect to CC: (1) reduced overall sapling recruitment, (2) increased recruitment of species dispersed by abiotic means, (3) altered relative abundances of species, (4) prominence of large-seeded species among those showing depressed recruitment, and (5) little or no tendency for saplings to cluster closer to adults at BM. Our results affirmed each of these predictions. Interpreted at face value, the evidence suggests that few species are demographically stable at BM and that up to 28% are increasing and 72% decreasing. Loss of dispersal function allows species dispersed abiotically and by small birds and mammals to substitute for those dispersed by large birds and mammals. Although we regard these conclusions as preliminary, over the long run, the observed type of directional change in tree composition is likely to result in biodiversity loss and negative feedbacks on both the animal and plant communities. Our results suggest that the best, and perhaps only, way to prevent compositional change and probable loss of diversity in tropical tree communities is to prohibit hunting

Accuracy of synovial fluid analysis compared to histology for the identification of calcium pyrophosphate crystals: An ancillary study of the OMERACT US working group - CPPD subgroup

The aim of this study was to evaluate the accuracy of synovial fluid analysis in the identification of calcium pyrophosphate dihydrate crystals compared to microscopic analysis of joint tissues as the reference standard. This is an ancillary study of an international, multicentre cross-sectional study performed by the calcium pyrophosphate deposition disease (CPPD) subgroup of the OMERACT Ultrasound working group. Consecutive patients with knee osteoarthritis (OA) waiting for total knee replacement surgery were enrolled in the study from 2 participating centres in Mexico and Romania. During the surgical procedures, synovial fluid, menisci and hyaline cartilage were collected and analysed within 48 hours from surgery under transmitted light microscopy and compensated polarised light microscopy for the presence/absence of calcium pyrophosphate crystals. All slides were analysed by expert examiners on site, blinded to other findings. A dichotomic score (absence/presence) was used for scoring both synovial fluid and tissues. Microscopic analysis of knee tissues was considered the gold standard. Sensitivity, specificity, accuracy, positive and negative predictive values of synovial fluid analysis in the identification of calcium pyrophosphate crystals were calculated.15 patients (53% female, mean age 68 yo +/- 8.4) with OA of grade 3 or 4 according to Kellgren-Lawrence scoring were enrolled. 12 patients (80%) were positive for calcium pyrophosphate crystals at the synovial fluid analysis and 14 (93%) at the tissue microscopic analysis. The overall diagnostic accuracy of synovial fluid analysis compared with histology for CPPD was 87%, with a sensitivity of 86% and a specificity of 100%, the positive predictive value was 100% and the negative predictive value was 33%.In conclusion synovial fluid analysis proved to be an accurate test for the identification of calcium pyrophosphate dihydrate crystals in patients with advanced OA