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Accumulation of essential/beneficial and non-essential chemical elements by submerged (Stuckenia pectinata (L.) Börner) and emergent (Phragmites australis (Cav.) Trin. ex Steud.) rooted macrophytes in three water bodies was studied as dependent on water salinity (specific conductivity) and main environmental factors (temperature, pH of water, growing period, element contents in water and sediments). Inductively coupled plasma optical emission spectrometry (ICP - OES) was used for the element detection in the plants, sediments, and water. Multivariate statistics redundancy analysis (RDA) showed that investigated factors together explained 37.8 - 44.7% and 29.9 - 42.6% of the essential/beneficial and non-essential elements variability, respectively, whereas salinity was one of the main factors determining the accumulation of a number of elements (Mg, S, Na, Li, Sr, Sb) by the macrophytes. A decrease in the essential element contents (K, P, N, Cu, Zn) was observed in both species of the macrophytes during the growing season. Environmental factors (salinity, growing period, and pH) were more significant than the element contents in water and the sediments for the essential/beneficial element accumulation by two species of the macrophytes. The element contents in the sediments to a greater extent determined non-essential element accumulation by P. australis than by S. pectinata. The study showed that the efficiency of using P. australis and S. pectinata for remediation of aquatic ecosystems contaminated by heavy metals should not decrease with a salinity increase.

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Setting dialysate sodium allows to adequately adjust sodium balance and plasma sodium at the end of dialysis session. In accordance with the set-point theory based on the concept of restoring cellular hydration, an adequate target for plasma sodium at the end of the session could be the value of predialysis plasma sodium concentration (isonatric hemodialysis). Some recently available dialysis monitors provide an on-line value of plasma-water conductivity usually converted in on-line natremia. There are different modalities of isonatric hemodialysis depending on whether the online value of natremia is used or not. By reviewing the few studies concerning the isonatric hemodialysis, it seems logical to set a target of postdialysis on-line natremia (or plasma-water conductivity) slightly lower than its predialysis value. However this strategy requires specifically designed software not yet available in clinical routine.

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Weakly electric fishes continually emit electric organ discharges (EOD) as a means of communication and localization of objects in their surroundings. Depending on water conductivity, the amplitude of the electric field generated is known to increase with decreases in electrical conductivity of the water. In Amazonian terra firme streams, water conductivity is extremely low and fluctuates constantly due to local and regional rains. In this context, the space between freely moving weakly electric fishes may be expected to decrease, on average, with an increase in water conductivity. To test this hypothesis, we recorded the positions at rest of the sand-dwelling fish Gymnorhamphichthys rondoni in a terra firme stream for several days in alternating months, over two years. Based on daily nearest neighbor distances among individual fish in a grid, we found a uniform temporal distribution pattern (which was not affected by water conductivity) indicative of site fidelity. Here we highlight the role of other factors that could influence resting site fidelity.(AU)

Los peces eléctricos emiten continuamente descargas con su órgano eléctrico (DOE) para comunicarse y localizar objetos a su alrededor. Dependiendo de la conductividad del agua, la amplitud del campo eléctrico generado aumenta con una disminución en la conductividad eléctrica del agua. En los arroyos de terra firme amazónicos, la conductividad eléctrica del agua es extremadamente baja y fluctua constantemente dependiendo de las lluvias locales y regionales. Teniendo esto en cuenta, esperamos que el espacio entre peces eléctricos débiles con libertad de movimiento disminuya, en promedio, de acuerdo al incremento en la conductividad del agua. Para evaluar esta hipótesis, registramos bajo condiciones naturales por varios dias en meses alternos y durante dos años las posiciones en reposo del pez Gymnorhamphichthys rondoni en un arroyo de terra firme. Con los valores de registro diario de la distancia al vecino mas cercano en peces individuales dentro de una grilla, encontramos un patrón de distribución temporal uniforme (que no fue afectado por la conductividad del agua) e indicativo de una fidelidad por los sitios de reposo. Entonces, nosotros resaltamos aquí el posible papel que otros factores pueden estar jugando para entender la fidelidad por sus sitios de reposo.(AU)

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Productivity is low and unstable in dryland farms of central Gansu, Northwest China. Conservational tillage is an important way for the sustainable development of agriculture. The effects of different tillage measures on soil moisture infiltration, evaporation, crop yield and water use efficiency (WUE) were investigated in this study based on a long-term experiment since 2001 in Longzhong. There were six treatments, i.e. conventional tillage with no straw (T), no-till with straw cover (NTS), no-till with no straw cover (NT), conventional tillage with straw incorporated (TS), conventional tillage with plastic mulch (TP), and no-till with plastic mulch (NTP), with annual rotation of spring wheat and pea. The results showed that compared with T, soil bulk density of NTS decreased and total porosity of soil increased significantly in wheat and pea land. Compared with conventional tillage, conservation tillage reduced soil infiltration rate in 0-5 cm in the pea field by 56.2%. Conservational tillage siginificantly increased soil saturated water conductivity in both wheat and pea lands. Compared with T, the saturated water conductivity in NTS was significantly increased by 52.8%-107.1%. Conservational tillage siginificantly reduced soil evaporation during growing season. Compared with T, the evapotranspiration of NTP, TP and NTS was significantly reduced by 14.4%-50.8%. The soil evaporation after rain was also decreased. Conservational tillage improved crop yield and water use efficiency by 9.5%-62.8% and 0.4%-50.9%, respectively. Therefore, conservational tillage could increase water use efficiency and crop yield in dryland farming area of central Gansu, Northwest China.

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BACKGROUND: Isonatric hemodialysis aims at maintaining stable cellular hydration through a close control of natremia, considered a surrogate of tonicity. However, 2 methods are available to perform isonatric hemodialysis: one based on natremia derived from plasma conductivity (NaCond) and the other based on natremia measured at laboratory (NaLab). We compared the control of tonicity obtained by isonatric hemodialysis based on NaLab or NaCond. METHODS: Changes in tonicity NaLab and NaCond were recorded during 55 hemodialysis sessions. Sessions were divided according to the variation of tonicity: hypotonic sessions (tonicity decrease ≥2 mOsm/kg); isotonic sessions (tonicity variation <2 mOsm/kg); hypertonic sessions (tonicity increase ≥2 mOsm/kg). RESULTS: During isotonic hemodialysis, NaCond decreases significantly by 1 mmol/L, whereas NaLab remained stable. CONCLUSIONS: Isonatric hemodialysis based on NaLab and isonatric hemodialysis based on NaCond is to be distinguished. Isotonic hemodialysis could be performed by decreasing NaCond by 1 mmol/L or maintaining NaLab stability.

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Underwater Wireless Sensor Network (UWSN) communication at high frequencies is extremely challenging. The intricacies presented by the underwater environment are far more compared to the terrestrial environment. The prime reason for such intricacies are the physical characteristics of the underwater environment that have a big impact on electromagnetic (EM) signals. Acoustics signals are by far the most preferred choice for underwater wireless communication. Because high frequency signals have the luxury of large bandwidth (BW) at shorter distances, high frequency EM signals cannot penetrate and propagate deep in underwater environments. The EM properties of water tend to resist their propagation and cause severe attenuation. Accordingly, there are two questions that need to be addressed for underwater environment, first what happens when high frequency EM signals operating at 2.4 GHz are used for communication, and second which factors affect the most to high frequency EM signals. To answer these questions, we present real-time experiments conducted at 2.4 GHz in terrestrial and underwater (fresh water) environments. The obtained results helped in studying the physical characteristics (i.e., EM properties, propagation and absorption loss) of underwater environments. It is observed that high frequency EM signals can propagate in fresh water at a shallow depth only and can be considered for a specific class of applications such as water sports. Furthermore, path loss, velocity of propagation, absorption loss and the rate of signal loss in different underwater environments are also calculated and presented in order to understand why EM signals cannot propagate in sea water and oceanic water environments. An optimal solk6ution for underwater communication in terms of coverage distance, bandwidth and nature of communication is presented, along with possible underwater applications of UWSNs at 2.4 GHz.

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Citrus blight is an economically important decline disease of citrus in various areas of the world. The cause of citrus blight is unknown, but transmission via root grafting has been demonstrated. Root tissue from fibrous roots of citrus blight-affected and healthy citrus trees were compared. Amorphous plugs of the type previously observed in the trunk xylem and large roots of blighted trees were also found in the fibrous roots. The plugs were yellow to light gold in color, gave a positive staining reaction for the presence of lignin, and were retained when kept overnight in water. With scanning electron microscopy the amorphous plugs appeared to be solid, occluding part or all of the vessel. These plugs have previously been implicated in the reduction of water transmission in blighted trees.

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Vessel dimensions (total diameter and length) were determined in tropical and subtropical plants of different growth forms with an emphasis upon lianas (woody vines). The paint infusion and compressed air methods were used on 38 species from 26 genera and 16 families in the most extensive survey of vessel length made to date. Within most stems there was a skewed frequency distribution of vessel lengths and diameter, with many short and narrow vessels and few long and wide ones. The longest vessel found (7.73 m) was in a stem of the liana (woody vine) Pithecoctenium crucigerum. Mean vessel length for 33 species of lianas was 0.38 m, average maximum length was 1.45 m. There was a statistically significant inter-species correlation between maximum vessel length and maximum vessel diameter. Among liana stems and among tree+shrub stems there were statistically significant correlations between stem xylem diameter and vessel dimensions. Lianas with different adaptations for climbing (tendril climbers, twiners, scramblers) were similar in their vessel dimensions except that scramblers tended to have shorter (but not narrower) vessels. Within one genus, Bauhinia, tendril climbing species had greater maximum vessel lengths and diameters than tree and shrub species. The few long and wide vessels of lianas are thought to hydraulically compensate for their narrow stem diameters. The many narrow and short vessels, which are present in the same liana stems, may provide a high resistance auxiliary transport system.