Automatedly identify dryland threatened species at large scale by using deep learning

Dryland biodiversity is decreasing at an alarming rate. Advanced intelligent tools are urgently needed to rapidly, automatedly, and precisely detect dryland threatened species on a large scale for biological conservation. Here, we explored the performance of three deep convolutional neural networks (Deeplabv3+, Unet, and Pspnet models) on the intelligent recognition of rare species based on high-resolution (0.3 m) satellite images taken by an unmanned aerial vehicle (UAV). We focused on a threatened species, Populus euphratica, in the Tarim River Basin (China), where there has been a severe population decline in the 1970s and restoration has been carried out since 2000. The testing results showed that Unet outperforms Deeplabv3+ and Pspnet when the training samples are lower, while Deeplabv3+ performs best as the dataset increases. Overall, when training samples are 80, Deeplabv3+ had the best overall performance for Populus euphratica identification, with mean pixel accuracy (MPA) between 87.31 % and 90.2 %, which, on average is 3.74 % and 11.29 % higher than Unet and Pspnet, respectively. Deeplabv3+ can accurately detect the boundaries of Populus euphratica even in areas of dense vegetation, with lower identification uncertainty for each pixel than other models. This study developed a UAV imagery-based identification framework using deep learning with high resolution in large-scale regions. This approach can accurately capture the variation in dryland threatened species, especially those in inaccessible areas, thereby fostering rapid and efficient conservation actions.

Spatial and temporal downscaling schemes to reconstruct high-resolution GRACE data: A case study in the Tarim River Basin, Northwest China

Climate change and excessive exploitation of water resources exert pressure on groundwater supply and the ecosystem in drylands. Although The Gravity Recovery and Climate Experiment (GRACE) satellites has demonstrated the feasibility of quantifying global groundwater storage variations, monitoring regional-scale groundwater has been challenging due to the coarse resolution of GRACE. Previous GRACE downscaling studies focused on develop new algorithms based on the perspective of pixel spatial correlation to improve resolution, which cannot better capture the temporal evolution of GRACE data effectively. In this study, we employ the semi-supervised variational autoencoder (SSVAER) algorithm and the multi-scale geographically weighted regression (MGWR) model to establish two different downscaling schemes: pixel temporal continuity downscaling and pixel spatial correlation downscaling. These schemes achieve spatial resolution downscaling of GRACE-derived groundwater storage anomalies (GWSA) from 0.5° to 0.1°. Additionally, the applicability of the PCR-GLOBWB model in drylands is verified. Furtherly, the spatiotemporal distribution patterns of GWSA are analyzed. The results show that (1) Both the temporal and spatial downscaling methods produced consistent results, with data correlations ranged from 0.94 to 0.98 observed in over 80 % of the range before and after downscaling; (2) The groundwater storage change rate in the northern Tarim River Basin (TRB) is 25 times greater than the model results, while in other regions, the average deviation is 2.6 times; (3) The two schemes enhance the correlation (0.27) between GWSA and groundwater level anomaly (GWLA) to 0.59 and 0.52, respectively, with a three-month lag in GWSA relative to GWLA. The temporal downscaling approach exhibited higher CC and lower RMSE, outperforming the spatial downscaling approach. The high-resolution results in this study can well complement groundwater level prediction efforts in arid regions and provide quantitative information for local water resource management.

Botulinum toxin infusion into the mesenteric artery has selective action on peristalsis in a rat model: experimental research

OBJECTIVE

Botulinum toxin type A (BoNT/A) reversibly blocks neurotransmission at voluntary and autonomic cholinergic nerve terminals, inducing paralysis. The aim of this study was to block panenteric peristalsis in rats through BoNT/A administration into the superior mesenteric artery (SMA) and to understand whether the toxin's action is selectively restricted to the perfused territory.

MATERIALS AND METHODS

Rats were infused through a 0.25-mm surgically inserted SMA catheter with different doses of BoNT/A (10 U, 20 U, 40 U BOTOX®, Allergan Inc.) or with saline for 24 h. Animals were free to move on an unrestricted diet. As a sign of bowel peristalsis impairment, body weight and oral/water intake were collected for 15 days. Statistical analysis was conducted with nonlinear mixed effects models to study the variation over time of the response variables. In three 40 U-treated rats, the selectivity of the intra-arterial delivered toxin action was studied by examining bowel and voluntary muscle samples and checking the presence of BoNT/A-cleaved SNAP-25 (the smoking gun of the toxin action) using the Immunofluorescence (IF) method through a specific antibody recognition.

RESULTS

While control rats exhibited an increasing body weight, treated rats showed an initial dose-dependent weight reduction (p<0.001 control vs. treated) with recovery after Day 11 for 10 and 20 U-treated rats. Food and water intake over time showed significantly different half-saturation constants with rats treated with higher doses who reached half of the maximum achievable in a greater number of days (p<0.0001 control vs. treated rats). BoNT/A-cleaved SNAP-25 was identified in bowel wall NMJs and not in voluntary muscles, demonstrating the remarkable selectivity of arterially infused BoNT/A.

CONCLUSIONS

Blockade of intestinal peristalsis, can be induced in rats by slow infusion of BoNT/A into the SMA. The effect is long-lasting, dose-dependent and selective. BoNT/A delivery into the SMA through a percutaneous catheter could prove clinically useful in the treatment of entero-atmospheric fistula by temporarily reducing fistula output.

Effects of Human Activities on Evapotranspiration and Its Components in Arid Areas

With the increasing impact of human activities on the environment, evapotranspiration (ET) has changed in arid areas, which further affects the water resources availability in the region. Therefore, understanding the impact of human activities on ET and its components is helpful to the management of water resources in arid areas. This study verified the accuracy of Fisher's model (PT-JPL model) for ET estimation in southern Xinjiang, China by using the evaporation complementarity theory dataset (AET dataset). The ET and the evapotranspiration components (T:E) of six land-use types were estimated in southern Xinjiang from 1982 to 2015, and the impact of human activities on ET was analyzed. In addition, the impact of four environmental factors (temperature (Temp), net radiation (Rn), relative humidity (RH), and NDVI) on ET were evaluated. The results showed that the calculated ET values of the PT-JPL model were close to the ET values of the AET dataset. The correlation coefficient (R2) was more than 0.8, and the NSE was close to 1. In grassland, water area, urban industrial and mining land, forest land, and cultivated land, the ET values were high, and in unused land types, the ET values were the lowest. The T:E values varied greatly in urban industrial and mining land, forest land, and cultivated land, which was due to the intensification of human activities, and the values were close to 1 in summer in recent years. Among the four environmental factors, temperature largely influenced the monthly ET. These findings suggest that human activities have significantly reduced soil evaporation and improved water use efficiency. The impact of human activities on environmental factors has caused changes in ET and its components, and appropriate oasis expansion is more conducive to regional sustainable development.

Analysis of desertification combating needs based on potential vegetation NDVI-A case in the Hotan Oasis

Combating desertification is vital for arresting land degradation and ensuring sustainable development of the global ecological environment. This study has analyzed the current desertification status and determined its control needs based on the difference between potential normalized difference vegetation index (PNDVI) and actual normalized difference vegetation index (ANDVI) in the Hotan desertoasis. The MaxEnt model, combined with the distribution point data of natural vegetation with long-term stable normalized difference vegetation index (NDVI) and 24 environmental factors was used to predict the PNDVI spatial distribution of different vegetation coverage grades and compared it with ANDVI. Excluding the areas of intense human activity such as arable land, the simulation results show that PNDVI with high, medium, and low vegetation cover was mainly distributed in the southwest and southeast of Hotan Oasis, in the midstream and downstream of Kalakash River and Yulong Kashi River, and the desert or Gobi area outside the oasis, respectively. The distribution of PNDVI with high, medium, and low vegetation cover accounted for 6.80%, 7.26%, and 9.17% of Hotan oasis, respectively. The comparison between ANDVI and PNDVI shows that 18.04% (ANDVI < PNDVI, about 3900 km²) of the study area is still suffering from desertification, which is mainly distributed in the desert-oasis ecotone in Hotan. The findings of this study implied that PNDVI could be used to assess the desertification status and endorsement of desertification control measures in vulnerable ecosystems. Hence, PNDVI can strengthen the desertification combating efforts at regional and global scales and may serve as a reference point for the policymakers and scientific community towards sustainable land development.

Extraction of multi-scale features enhances the deep learning-based daily PM2.5 forecasting in cities

Characterising the daily PM2.5 concentration is crucial for air quality control. To govern the status of the atmospheric environment, a novel hybrid model for PM2.5 forecasting was proposed by introducing a two-stage decomposition technology of complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and variational mode decomposition (VMD); subsequently, a deep learning approach of long short-term memory (LSTM) was proposed. Five cities with unique meteorological and economic characteristics were selected to assess the predictive ability of the proposed model. The results revealed that PM2.5 pollution was generally more severe in inland cities (66.98 ± 0.76 μg m^-3) than in coastal cities (40.46 ± 0.40 μg m-3). The modelling comparison showed that in each city, the secondary decomposition algorithm improved the accuracy and prediction stability of the prediction models. When compared with other prediction models, LSTM effectively extracted featured information and achieved relatively accurate time-series prediction. The hybrid model of CEEMDAN-VMD-LSTM achieved a better prediction in the five cities (R2 = 0.9803 ± 0.01) compared with the benchmark models (R2 = 0.7537 ± 0.03). The results indicate that the proposed approach can identify the inherent correlations and patterns among complex datasets, particularly in time-series analysis.

Occurrences, transport drivers, and risk assessments of antibiotics in typical oasis surface and groundwater

Intensive use of antibiotics affects biogeochemical cycles and stimulates the evolution of antibiotic resistance, thus threatening global health and social development. The spatiotemporal distributions of antibiotics in single aqueous matrices have been widely documented; however, their occurrence in surface-groundwater systems has received less attention, especially in arid regions that usually have fragile ecosystems. Therefore, we investigated the occurrence of thirty-one antibiotics in the surface water and adjacent groundwater in the Xinjiang Uygur Autonomous Region, China. The results showed that the total concentrations of detected antibiotics varied from 17.37 to 84.09 ng L^-1 and from 16.38 to 277.41 ng L^-1 in surface and groundwater, respectively. The median concentration of antibiotics showed the pattern of norfloxacin (4.86 ng L^-1) > ciprofloxacin (3.93 ng L^-1) > pefloxacin (3.39 ng L^-1) in surface water; whereas in groundwater, this was in the order of pefloxacin (6.30 ng L^-1) > norfloxacin (4.33 ng L^-1) > ciprofloxacin (2.68 ng L^-1). Heatmap analysis indicated that vertical infiltration had limited effects on antibiotic exchange in surface-ground water systems because of the high potential evaporation and low water storage. Redundancy analysis suggested that the oxidation-reduction potential (p < 0.01) and dissolved oxygen (p < 0.05) jointly affected the distribution of antibiotics in surface water. Ecological risk assessment showed that antibiotics in 98.9% of surface water and 99.1% of groundwater did not pose significant risks to aquatic species. The findings of this study will help develop effective mitigation strategies for antibiotics in aquatic environments.

Simulation of regional groundwater levels in arid regions using interpretable machine learning models

Regional groundwater level forecasting is critical to water resource management, especially for arid regions which require effective management of groundwater resources to meet human and ecosystem needs. In this study Machine Learning and Deep Learning approaches - Support Vector Machine, Generalized Regression Neural Network, Decision Tree, Random Forest (RF), Convolutional Neural Network, Long Short Term Memory and Gated Recurrent Network- have been used to simulate the groundwater levels in the lower Tarim River basin (LTRB) which is an extreme dryland. The results showed that models developed here with easily available input data such as relative humidity, flow volume and distance to the riverbank can fully utilize spatiotemporally inconsistent groundwater monitoring data to predict the spatiotemporal variation of the groundwater system in arid regions where exist intermittent flow. The shapely additive explanations method was used to interpret the RF model and discover the effect of meteorological, hydrological and environmental variables on the regional groundwater. These explanations showed that the flow volume, the distance to the river channel and reservoir have a critical impact on groundwater changes. Within 300 m distance to the riverbank, groundwater would mainly be influenced by the flow volume and the distance to the reservoir. While far from the riverbank, these effects decreased gradually further away from the river course. The RF prediction results showed that in the next three years (2021-2023), the groundwater level on average may decline to -6.4 m, and the suitable areas for natural vegetation growth would be limited to 39% if no water conveyance in the LTRB. To guarantee the stability of ecosystems in the LTRB, it is necessary to convey the water annually. These results can support spatiotemporal predictions of groundwater levels predominantly recharged by intermittent flow, and form a scientific basis for sustainable water resources management in arid regions.

Assessing landscape fragmentation in a desert-oasis region of Northwest China: patterns, driving forces, and policy implications for future land consolidation

Landscape fragmentation is considered a serious threat to eco-environmental integrity and socioeconomic development. Although many studies have focused on landscape fragmentation resulting from agricultural production and urbanization, landscape fragmentation from the aspects of patterns, driving forces, and the policy perspective of ecosystems has rarely been investigated. Oases, as a unique landscape, face severe fragmentation in arid and semiarid regions. This study applied a combination of approaches, including remote sensing image interpretations, landscape fragmentation metrics, and community surveys, to analyze patterns and their driving forces, as well as the policy implications for future land consolidation, in the Hotan oasis of Northwest China from the space and time perspectives. Results show that the frequent occurrence of summer flood events changes the patch number, density, size, and splitting degree of oasis-desert ecotone vegetation. The socioeconomic factors including total population and irrigation area are more important driving forces on oasis landscape fragmentation, compared with natural factors such as temperature and precipitation. Rural expansion, road and canal system developments caused by population growth, and the rising number of households increase oasis landscape fragmentation. Rapid economic development, such as agricultural expansion and urbanization, has imposed the intensification of landscape fragmentation. Fragmentation reaches peak when agricultural development makes up 40-50% of study area. Rural residential reconstruction and farmland transfer policies facilitate the intensive utilization of land toward oasis fragmentation solutions, but many factors, such as landholders' household characteristics and living conditions, are partly responsible for the challenges in land consolidation. This study also demonstrates that intense human activities pose a great threat for land consolidation and sustainable development of oasis landscape.

Oasis sustainability assessment in arid areas using GRACE satellite data

An oasis is an important habitat for humans, plants, and wildlife in arid desert areas. The sustainability of an oasis is crucial for a smooth regional ecological functioning and healthy economic development. However, the overexploitation of groundwater will result in unsustainable oasis development. Due to the lack of long-term groundwater monitoring data, the impact of groundwater level changes on the sustainability of an oasis has not been studied extensively. In the present study, we used the ground water storage anomaly (GWSA) in combination with the Gravity Recovery and Climate Experiment (GRACE) and the Global Land Data Assimilation System (GLDAS) for the rapid identification of oasis sustainability, which has been tested and evaluated in Hotan and Qira oasis located in arid areas. The results showed that (1) the GWSA is a suitable and reliable indicator for trend change analysis in small-scale oasis and, (2) additionally, M-K test results for long-term trend change of GWSA showed a positive correlation with water resource carrying capacity (WRCC). These results suggest that GWSA can be used as a reliable index for the rapid assessment of oasis sustainability status in arid areas. Moreover, the potential applicability of GRACE satellite data in evaluating the groundwater sustainability in arid areas lacking proper data has also been proved in this study. These findings have provided a foundation to evaluate the sustainability status of an oasis and set a reference point to formulate future policies for the oasis.

Spatial distribution and source apportionment of polycyclic aromatic hydrocarbons in typical oasis soil of north-western China and the bacterial community response

Oases environments in oases to be sensitive to anthropogenic activity because of ecological fragility. Polycyclic aromatic hydrocarbon (PAH) pollution resulting from anthropogenic activity leads to ecological degradation in oases. To examine the impact of anthropogenic activity on the oasis ecological environment, the present study focused on the spatial distribution and source apportionment of soil PAHs and bacterial community responses in typical oases in Xinjiang, China. The results showed that the soil PAH level were higher in the city centres of Urumqi (9-6340 μg kg^-1), Aksu (8-957 μg kg^-1) and Korla (8-1103 μg kg^-1) and lower in the centres of Hotan city (11-268 μg kg^-1) and Qira county (7-163 μg kg^-1). Source apportionment suggested that gasoline emissions, diesel emissions, vehicle emissions, coal combustion, coke processing and biomass burning were the sources of soil PAHs. The integrated lifetime cancer risks of soil PAH exceeding the guideline safety values (10^-6) recommended by United States Environmental Protection Agency. The ingestion and dermal exposure pathways caused the greatest health risk (contribution ≤82%). Additionally, in the soil with low PAH concentrations, the richness and evenness of the soil bacterial community were great, and the molecular ecological network (MEN) structure was complex. Among populations, Proteobacteria and Actinobacteria (relative abundance ≥17%) are the main dominant species in the bacterial communities and the keystone species in the MEN.

Closed incision Negative Pressure Therapy (ciNPT): does depression affect underlying tissues?

OBJECTIVE

Closed incision Negative Pressure Therapy (ciNPT) has become a widespread practice in recent years. Described benefits concern the rate of wound infection, based on the assumption that negative pressure spreads inside the wound removing collections and edema. The study aims to clarify this technical point, on which experimental scientific evidence is lacking in literature.

MATERIALS AND METHODS

In the experimental animal (newly sacrificed pig), the pressure was measured for hours at the bottom of three surgical abdominal wounds sutured by planes and dressed in negative pressure therapy commercial sets.

RESULTS

The depression applied to the surface of the sutured wounds (ciNPT) is not transmitted to the underlying tissues. The blue dye deposited in the deep layer of the wounds didn't surface as an effect of ciNPT.

CONCLUSIONS

The possible benefits deriving from the application of negative pressure on sutured wounds must depend on a different mechanism from the diffusion of depression in the wound planes and in the underlying tissues.

Linking soil profile N2O concentration with surface flux in a cotton field under drip fertigation

It remains unclear how the source and rate of nitrogen (N) fertilizers affect N₂O concentration and effluxes along the soil profile under the drip-fertigated agricultural system. A plot-based field study was performed in 2017 and 2018 in a cotton field in arid northwestern China, with an objective to elucidate the impact of the applications of conventional urea (Urea), polymer-coated urea (ESN) and stabilized urea (SuperU) at rates of 120 and 240 kg N ha^-1 on concentration and efflux of N₂O in the soil profile and its relationship with N₂O surface emissions. The in-situ N₂O concentrations at soil depths of 5, 15, 30 and 60 cm were measured and used to estimate soil profile N₂O effluxes. Estimates of surface N₂O flux using the concentration gradient-based (GM) were compared with those measured using the chamber-based (CM) method. In both years, soil N₂O concentrations at all depths increased in response to basal N application at planting or in-season fertigation events. However, N rate or source did not affect soil N₂O concentrations or effluxes at each depth. Surface emissions of N₂O were mostly associated with that presented in the top layer of 0-15 cm. Surface N₂O efflux determined by GM was poorly or not associated with those of chamber measurements, which was attributed to the low N₂O production restricted by soil moisture condition under the drip-fertigated condition. These results highlight the challenge of applying the enhanced efficiency N fertilizer products in the drip-fertigated agricultural system.

Estimating evapotranspiration by coupling Bayesian model averaging methods with machine learning algorithms

Evapotranspiration (ET) is one of the most important components of global hydrologic cycle and has significant impacts on energy exchange and climate change. Numerous models have been developed to estimate ET so far; however, great uncertainties in models still require considerations. The aim of this study is to reduce model errors and uncertainties among multi-models to improve daily ET estimate. The Bayesian model averaging (BMA) method is used to assemble eight ET models to produce ET with Landsat 8 satellite data, including four surface energy balance models (i.e., SEBS, SEBAL, SEBI, and SSEB) and four machine learning algorithms (i.e., polymars, random forest, ridge regression, and support vector machine). Performances of each model and BMA method were validated through in situ measurements of semi-arid region. Results indicated that the BMA method outperformed all eight single models. The four most important models obtained by the BMA method were ranked by random forest, SVM, SEBS, and SEBAL. The BMA method coupled with machine learning can significantly improve the accuracy of daily ET estimate, reducing uncertainties among models, and taking different intrinsic benefits of empirically and physically based models to obtain a more reliable ET estimate.

Enhanced efficiency nitrogen fertilizers were not effective in reducing N2O emissions from a drip-irrigated cotton field in arid region of Northwestern China

Drip irrigation is an effective water-saving strategy for crop production in arid regions. However, limited information is available on how fertilizer nitrogen (N) management affects soil nitrous oxide (N₂O) emission under drip irrigation. A two-year (2017-2018) field experiment was conducted in arid northwestern China to test management options of fertilizer N to reduce N₂O emission and improve NUE of cotton (Gossypium hirsutum L.) under drip irrigation. Treatment included a factorial design of rate (120, 240 kg N ha^-1) and source of N fertilizer (Urea, polymer-coated urea-ESN, stabilized urea with nitrification and urease inhibitors-SuperU), and an unfertilized Control. Urea was split-applied with irrigation water (fertigation) whereas ESN and SuperU were all side-banded at pre-plant. Crop yield and N uptake, soil mineral N concentrations, soil temperature and moisture, and N₂O fluxes were determined. Across the two growing seasons, a single pre-plant application with ESN or SuperU significantly increased growing season cumulative N₂O emissions (ƩN₂O) by 29-47% and applied N-scaled emission factor (EF) by 57-83% compared to urea fertigation, irrespectively of application rate. In contrast, cotton yield, agronomic NUE, apparent N recovery (ANR), and yield-based N₂O emission intensity (EI) were not affected by N source. Reducing N rate from 240 to 120 kg N ha^-1 significantly decreased ƩN₂O by 35% in 2017 and 36% in 2018 while simultaneously reduced cotton yield in both years. The increased N₂O emissions with ESN and SuperU were attributed to greater availability of inorganic N resulted from one-time application at pre-plant and higher soil temperature. We concluded that fertigation with urea at the recommended rate is the best option to ensure agronomic productively and agronomic NUE with minimal risk of N₂O emissions. In contrast, the benefit of enhanced efficiency N fertilizer is limited and recommendation on using of these products is challenging for arid croplands under drip irrigation.

Differential physio-biochemical and yield responses of Camelina sativa L. under varying irrigation water regimes in semi-arid climatic conditions

Camelina sativa L. is an oilseed crop with wide nutritional and industrial applications. Because of favorable agronomic characteristics of C. sativa in a water-limiting environment interest in its production has increased worldwide. In this study the effect of different irrigation regimes (I₀ = three irrigations, I₁ = two irrigations, I₂ = one irrigation and I₃ = one irrigation) on physio-biochemical responses and seed yield attributes of two C. sativa genotypes was explored under semi-arid conditions. Results indicated that maximum physio-biochemical activity, seed yield and oil contents appeared in genotype 7126 with three irrigations (I₀). In contrast water deficit stress created by withholding irrigation (I₁, I₂ and I₃) at different growth stages significantly reduced the physio-biochemical activity as well as yield responses in both C. sativa genotypes. Nonetheless the highest reduction in physio-biochemical and yield attributes were observed in genotype 8046 when irrigation was skipped at vegetative and flowering stages of crop (I₃). In genotypic comparison, C. sativa genotype 7126 performed better than 8046 under all I₁, I₂ and I₃ irrigation treatments. Because 7126 exhibited better maintenance of tissue water content, leaf gas exchange traits and chlorophyll pigment production, resulting in better seed yield and oil production. Findings of this study suggest that to achieve maximum yield potential in camelina three irrigations are needed under semi-arid conditions, however application of two irrigations one at flowering and second at silique development stage can ensure an economic seed yield and oil contents. Furthermore, genotype 7126 should be adopted for cultivation under water limited arid and semi-arid regions due to its better adaptability.

Percutaneous cholecystostomy in the treatment of acute cholecystitis: is there still a role? A 20-year literature review

OBJECTIVE

Percutaneous cholecystostomy (PC) is used for the treatment of acute cholecystitis in patients with high surgical risk due to the severity of cholecystitis and/or the underlying acute or chronic medical comorbidities. The evidence for this strategy is unclear.

MATERIALS AND METHODS

We searched PubMed and the Cochrane databases for English-language studies published from January 1979 through December 31, 2019, for randomized clinical trials (RCTs), meta-analyses, systematic reviews, and observational studies.

RESULTS

The two randomized studies that have compared PC with cholecystectomy (CCY) or conservative treatment have shown that the clinical outcomes did not differ significantly between the groups. Similar results have been found in the large majority of retrospective cohorts or single-center studies that have compared PC with CCY.

CONCLUSIONS

PC does not seem to offer any benefit compared with CCY in the treatment of acute cholecystitis in patients with high surgical risk due to the severity of cholecystitis and/or the underlying acute or chronic medical comorbidities. A large, prospective, randomized study that compares percutaneous PC and CCY in patients with high surgical risk and/or moderate to severe cholecystitis is warranted.

Comparison of the groundwater microbial community in a salt-freshwater mixing zone during the dry and wet seasons

To gain a better understanding of the microbial community in salt-freshwater mixing zones, in this study, the influence of seasonal variation on the groundwater microbial community was evaluated by high throughput 16S rDNA gene sequencing. The results showed that notable changes in microbial community occurred in a salt-freshwater mixing zone and the groundwater samples in the dry season were more saline than those in the wet season. The increase in precipitation during the wet season relieved local seawater intrusion. Microbial diversity varied greatly with seasons, while no obvious change pattern was found. Proteobacteria was identified as the dominant phylum in all samples. The genus Hydrogenophaga dominated in the dry season, while the genus Acidovorax dominated in the wet season. Dissolved oxygen affected the diversity of the microbial communities during the dry and wet season, while groundwater level had a strong influence on the structure of microbial communities. Phylogenetic molecular network analysis of the microbial communities indicated that increased seawater intrusion led to a more compact microbial network and strengthening the groundwater microbial interactions.

Acceleration of soil salinity accumulation and soil degradation due to greenhouse cultivation: a survey of farmers' practices in China

Soil environment and water quality face large pressure due to the rapid expansion of greenhouse cultivation in China. However, studies rarely provide the linkage between farmers' practices and soil degradation in greenhouse cultivation field. In this study, a field survey and sampling of greenhouse cultivation soil were conducted in five regions of China to investigate the accumulation and variation characteristics of soil ion compositions in the field. First, the pH, ion compositions, and electrical conductivity (EC) of 132 composite soil samples were analyzed. Second, farmers' practices with regard to fertilizer, crop yield, and soil degradation processes were surveyed. Lastly, soil nutrient status was evaluated by different grades, and the principal component analysis method was used to analyze the main sources of soil ion compositions. Results of the study reveal the following: (1) Enrichment of greenhouse soil nutrient was mainly caused by excessive fertilization, which introduced the secondary salinization phenomenon for 3-5 years in plastic greenhouse and 1-3 years in multispan greenhouse. (2) Significant changes between the EC and salt ion composition of open soil and greenhouse cultivated soil were observed. The contents of nitrate nitrogen and ammonium nitrogen in the greenhouse soil were high. (3) After a certain period of cultivation in the greenhouse, salt accumulation, pH decline, and varying degrees of acidification were observed in the soil profile. The relationship between soil pH and EC values indicated that the balance of soil compositions was broken. The recommended methods for sustaining greenhouse cultivation include balanced fertilization, rotation practices, and reasonable water utilization in the field.

Assessing water distribution and agricultural expansion in the Cele Oasis, China

Oases support 90% of the province's inhabitants and produce more than 95% of the social wealth in Xinjiang Province of China. Oases' dependency on water availability from mountainous regions plays a critical factor in the sustainability of agricultural practices and oasis expansion. In this study, we have chosen the Cele Oasis located in the south rim of the Taklimakan Desert, typical of oases in the region, as a case study to examine water availability. With over 97% of Cele's economy tied to agriculture, unfettered expansion of the oasis into the desert has raised concern on water availability. A spatial and temporal analysis of water availability is performed using newly available data to determine whether agricultural production within the Cele Oasis has overexploited available water resources or if feasible expansion of agricultural production is feasible beyond its current boundary. Transferability of the methodology for assessing water availability spatially and temporally will be beneficial to other oases in the arid region that face similar concerns.

Influence of surface properties and antecedent environmental conditions on particulate-associated metals in surface runoff

Particulate-associated trace metals have been regarded as an important pollution source for urban surface runoff. Cd, Pb, Cu, Zn and total solids (TS) washed off two different surfaces (low-elevated facade and road surfaces) under two kinds of antecedent environmental conditions (dry and snow-melting) were determined in this study. Wet-vacuuming sweeping (WVS) and surface washing (SW) methods, representing the maximum pollution potential and common rainfall-induced wash-off condition respectively, were used to collect the particulate matters. The result shows that the wash-off concentrations of trace metals were found in the order of Cd (2.28 ± 2.08 μg/l) < Pb (435.85 ± 412.61 μg/l) < Cu (0.93 ± 0.61 mg/l) < Zn (2.52 ± 2.30 mg/l). The snow-melting process had a considerable influence on the wash-off concentrations of the trace metals on both road and facade surfaces. It reduced >38% and >79% of metals and TS concentrations in the facade surface and road surface runoff respectively. The wash-off concentrations of Cd, Cu, and Zn on the road surface 45-780% higher than those on the facade surfaces. The sensitivity analysis based on the Bayesian network indicates that the wash-off concentrations of metals were mainly dependent on the antecedent environmental conditions or the surface properties while the sampling methods had a minor influence. Therefore, to accurately model the pollutant migration in the surface runoff requires an improving method considering different surfaces and antecedent environment conditions.

Agronomic evaluation of polymer-coated urea and urease and nitrification inhibitors for cotton production under drip-fertigation in a dry climate

Interest in the use of enhanced-efficiency nitrogen (N) fertilizers (EENFs) has increased in recent years due to their potential to increase crop yield and reduce environmental N loss. Drip-fertigation is widely used for crop production in arid regions to improve water and nutrient use efficiency whereas the effectiveness of EENFs with drip irrigation remains unclear. A field experiment was conducted in 2015 and 2016 to examine the effects of EENFs on yield, N use and quality of cotton (Gossypium hirsutum) grown under drip-fertigation in arid NW China. Treatments included an unfertilized control and application of 240 kg N ha^-1 by polymer-coated urea (ESN), urea alone, or urea plus urease (NBPT) and nitrification (DCD) inhibitors. ESN was all banded in the plant row at planting, whereas urea was applied with 20% N banded at planting and 80% N by six fertigation events over the growing season. Results showed there was generally no treatment effect on seed and lint yield, N concentration or allocations, N recovery efficiency and fiber quality index of cotton. A lack of treatment effect could be due to N supplied with drip-fertigation better synthesized with crop N needs and the relatively high soil native NO₃^- availability, which hindered the effect of polymer-coated urea and double inhibitors. These results highlight the challenge of the employment of EENFs products for drip-fertigation system in arid area. Further research is required to define the field conditions under which the agronomic efficiency of EENFs products may be achieved in accordance with weather conditions.

Presence of spring-thaw N2O emissions are not linked to functional gene abundance in a drip-fertigated cropped soil in arid northwestern China

Spring-thaw represents a significant source for nitrous oxide (N₂O) emissions from fertilized croplands in temperate regions. In this study, we present surface N₂O fluxes, soil-profile N₂O concentrations at 5, 15, 30 and 60 cm depths along with the abundance of nitrifiers and denitrifiers over the winter and spring-thaw periods in an arid, drip- fertigated cotton field, which had received spring application of 240 kg N ha^-1 as urea alone (Urea), polymer-coated urea (ESN), and urea plus urease and nitrification inhibitors. Nitrous oxide emissions from December to April were generally unaffected by fertilizer treatments with a cumulative average of 186 g N ha^-1, accounting for 39% of the annual N₂O emissions. Emission peaks occurred at spring-thaw and coincided with increasing soil-profile N₂O concentrations at all depths, suggesting the burst in N₂O fluxes was due to new N₂O production, rather than a physical release of N₂O trapped in the soil profiles over winter. The abundance of nitrifier and denitrifier genes changed over the winter and spring-thaw periods but was not affected by fertilizer treatments from the previous spring, suggesting the abundance of N₂O-producing microorganism was more controlled by environmental conditions than N sources applied in the previous spring. The daily N₂O flux rate from December to April was positively correlated with soil temperature, water-filled pore space, and denitrifying enzyme activity, but not with the gene copy number of AOA, AOB, narG, nirS, nirK and nosZ, indicating that variation in the abundance of these genes was not contributing to the N₂O emissions. These results suggest that N₂O emissions in spring-thaw are substantial for drip-fertigated croplands in the arid regions and should be considered in the annual budgets. The environmental factors such as soil temperature and moisture are likely more important than the copy-numbers of N₂O-producing functional genes in driving the variability in spring-thaw emissions.

Manure application increased denitrifying gene abundance in a drip-irrigated cotton field

Application of inorganic nitrogen (N) fertilizer and manure can increase nitrous oxide (N₂O) emissions. We tested the hypothesis that increased N₂O flux from soils amended with manure reflects a change in bacterial community structure and, specifically, an increase in the number of denitrifiers. To test this hypothesis, a field experiment was conducted in a drip-irrigated cotton field in an arid region of northwestern China. Treatments included plots that were not amended (Control), and plots amended with urea (Urea), animal manure (Manure) and a 50/50 mix of urea and manure (U+M). Manure was broadcast-incorporated into the soil before seeding while urea was split-applied with drip irrigation (fertigation) over the growing season. The addition treatments did not, as assessed by nextgen sequencing of PCR-amplicons generated from rRNA genes in soil, affect the alpha diversity of bacterial communities but did change the beta diversity. Compared to the Control, the addition of manure (U+M and Manure) significantly increased the abundance of genes associated with nitrate reduction (narG) and denitrfication (nirK and nosZ). Manure addition (U+M and Manure) did not affect the nitrifying enzyme activity (NEA) of soil but resulted in 39–59 times greater denitrifying enzyme activity (DEA). In contrast, urea application had no impact on the abundances of nitrifier and denitrifier genes, DEA and NEA; likely due to a limitation of C availability. DEA was highly correlated (r = 0.70–0.84, P < 0.01) with the abundance of genes narG, nirK and nosZ. An increase in the abundance of these functional genes was further correlated with soil NO₃⁻, dissolved organic carbon, total C, and total N concentrations, and soil C:N ratio. These results demonstrated a positive relationship between the abundances of denitrifying functional genes (narG, nirK and nosZ) and denitrification potential, suggesting that manure application increased N₂O emission by increasing denitrification and the population of bacteria that mediated that process.

Role of surgical setting and patients-related factors in predicting the occurrence of postoperative pulmonary complications after abdominal surgery

OBJECTIVE

The aim of this retrospective study was to evaluate the role of surgical setting (urgent vs. elective) and approach (open vs. laparoscopic) in affecting postoperative pulmonary complications (PPCs) prevalence in patients undergoing abdominal surgery.

PATIENTS AND METHODS

After local Ethical Committee approval, 409 patients who had undergone abdominal surgery between January and December 2014 were included in the final analysis. PPCs were defined as the development of one of the following new findings: respiratory failure, pulmonary infection, aspiration pneumonia, pleural effusion, pneumothorax, atelectasis on chest X-ray, bronchospasm or un-planned urgent re-intubation.

RESULTS

PPCs prevalence was greater in urgent (33%) vs. elective setting (7%) (χ2 with Yates correction: 44; p=0.0001) and in open (6%) vs. laparoscopic approach (1.9%) (χ2 with Yates correction: 12; p=0.0006). PPCs occurrence was positively correlated with in-hospital mortality (Biserial Correlation r=0.37; p=0.0001). Logistic regression showed that urgent setting (p=0.000), Ariscat (Assess Respiratory Risk in Surgical Patients in Catalonia) score (p=0.004), and age (p=0.01) were predictors of PPCs. A cut-off of 23 for Ariscat score was also identified as determining factor for PPCs occurrence with 94% sensitivity and 29% specificity.

CONCLUSIONS

Patients undergoing abdominal surgery in an urgent setting were exposed to a higher risk of PPCs compared to patients scheduled for elective procedures. Ariscat score fitted with PPCs prevalence and older patients were exposed to a higher risk of PPCs. Prospective studies are needed to confirm these results.

Groundwater Depth Affects Phosphorus But Not Carbon and Nitrogen Concentrations of a Desert Phreatophyte in Northwest China

Ecological stoichiometry is an important aspect in the analysis of the changes in ecological system composition, structure, and function and understanding of plant adaptation in habitats. Leaf carbon (C), nitrogen (N), and phosphorus (P) concentrations in desert phreatophytes can be affected by different depths of groundwater through its effect on the adsorption and utilization of nutrient and plant biomass. We examined the biomass, soil organic C, available (mineral) N, and available P, and leaf C, N, and P concentrations of Alhagi sparsifolia grown at varying groundwater depths of 2.5, 4.5, and 11.0 m in 2015 and 2016 growing seasons in a desert-oasis ecotone in northwest China. The biomass of A. sparsifolia and the C, N, and P concentrations in soil and A. sparsifolia showed different responses to various groundwater depths. The leaf P concentration of A. sparsifolia was lower at 4.5 m than at 2.5 and 11.0 m likely because of a biomass dilution effect. By contrast, leaf C and N concentrations were generally unaffected by groundwater depth, thereby confirming that C and N accumulations in A. sparsifolia were predominantly determined by C fixation through the photosynthesis and biological fixation of atmospheric N2, respectively. Soil C, N, and P concentrations at 4.5 m were significantly lower than those at 11.0 m. Leaf P concentration was significantly and positively correlated with soil N concentration at all of the groundwater depths. The C:N and C:P mass ratios of A. sparsifolia at 4.5 m were higher than those at the other groundwater depths, suggesting a defensive life history strategy. Conversely, A. sparsifolia likely adopted a competitive strategy at 2.5 and 11.0 m as indicated by the low C:N and C:P mass ratios. To our knowledge, this study is the first to elucidate the variation in the C, N, and P stoichiometry of a desert phreatophyte at different groundwater depths in an arid ecosystem.

Which is the Easiest and Safest Technique for Central venous Access? A Retrospective Survey of more than 5,400 Cases

There is an ongoing debate on the technique for central venous catheterization associated with the lowest complication rate and the highest success rate. In an attempt to better define the easiest and safest venous approach, we have reviewed our 7-year experience with 5479 central venous percutaneous punctures (by Seldinger's technique) for the insertion of short-term (n=2109), medium/long-term (n=2627) catheters, as well as double-lumen, large-bore catheters for hemodialysis and/or hemapheresis (n=743). We have analyzed the incidence of the most frequent insertion-related complications by comparing seven different venous approaches: jugular vein, low lateral approach; jugular vein, high lateral approach; jugular vein, low axial approach; subclavian vein, infraclavicular approach; subclavian vein, supraclavicular approach; external jugular vein; femoral vein.

The results of our retrospective study suggest that the ‘low lateral’ approach to the internal jugular vein, as described by Jernigan and modified according to our protocol, appears to be the easiest and safest technique for percutaneous insertion of central venous access, being characterized by the lowest incidence of accidental arterial puncture (1.2%) and malposition (0.8%), no pneumothorax, and an extremely low rate of repeated attempts (i.e. more than two punctures before successful cannulation) (3.3%). We advocate the ‘low lateral’ approach to the internal jugular vein as first-choice technique for venipuncture in both adults and children, for both short-term and long-term central venous percutaneous cannulation.

Comparison of cholecystectomy and percutaneous cholecystostomy in acute cholecystitis: results of a retrospective study

OBJECTIVE

To retrospectively compare the clinical outcomes of percutaneous cholecystostomy (PC) and cholecystectomy in patients with acute cholecystitis admitted to an urban University Hospital.

PATIENTS AND METHODS

We studied 646 patients with acute cholecystitis. Ninety patients had placement of a PC at their index hospitalization, and 556 underwent cholecystectomy. Of the 90 patients with PC, 13 underwent subsequent elective cholecystectomy.

RESULTS

Overall, in-hospital mortality and postoperative complications were significantly higher in patients who received PC than in those who underwent cholecystectomy. In the ASA score 1-2 group, patients with PC were significantly older and had a longer postoperative stay while their mortality and morbidity were similar to patients who underwent cholecystectomy. In patients with ASA score of 3, PC and cholecystectomy did not differ significantly for demographic variables and clinical outcomes such as hospital stay, in-hospital mortality, postoperative complications and distribution of complications according to the classification of Clavien-Dildo. In mild, moderate, and severe cholecystitis, patients who underwent PC were significantly older than those who received cholecystectomy. In general, in mild, moderate and severe cholecystitis, the clinical outcomes did not differ significantly between patients who received PC and cholecystectomy. Morbidity was higher in patients with mild cholecystitis who underwent PC. Of the 77 patients dismissed from the hospital with drainage, 12 (15.6%) developed biliary complications and 5 needed substitutions of the drainage itself.

CONCLUSIONS

PC does not offer advantages compared to cholecystectomy in the treatment of acute cholecystitis. Its routine use is therefore questioned. There is need of an adequate, randomized study that compares PC and cholecystectomy in high-risk patients with moderate-severe cholecystitis.

Stoichiometry in aboveground and fine roots of Seriphidium korovinii in desert grassland in response to artificial nitrogen addition

Nitrogen (N) input by atmospheric deposition and human activity enhances the availability of N in various ecosystems, which may further affect N and phosphorus (P) cycling and use by plants. However, the internal use of N, P, and N:P stoichiometry by plants in response to N supply, particularly for grass species in a desert steppe ecosystem, remains unclear. In this work, a field experiment was conducted at an infertile area in a desert steppe to investigate the effects of N fertilizer addition rates on the stoichiometry of N and P in a dominant grass species, Seriphidium korovinii. Results showed that for both aboveground and fine roots of S. korovinii, N inputs exponentially increased the N concentration and N:P ratios while P concentrations decreased. Meanwhile, the relationships between N and P concentrations for both aboveground and fine roots were significantly negative. Furthermore, while the N concentrations in the plants were relatively low, P concentrations were higher than the global means, resulting in a relatively low N:P ratio. These results suggest that the stoichiometric characteristics of N were different from that of P for this desert plant species. Results also show that the intraspecific variations in the main element traits (N, P, and N:P ratios) were consistent at the whole-plant level. Our results also suggest that N should be part of any short-term fertilization plan that is part of a management strategy designed to restore degraded desert grassland. These findings highlight that nutrient addition by atmospheric N deposition and human activity can have significant effects on the internal use of N and P by plants. Therefore, establishing a nutrient-conservation strategy for desert grasslands is important.

Negative pressure wound therapy (NPWT) in duodenal breakdown fistulas: negative pressure fistula therapy (NPFT)?

OBJECTIVE

To describe for the first time in literature the specific methodology of use of negative pressure wound therapy (NPWT) for duodenal fistula through clinical cases. The constant increase of use of NPWT for complex surgical situations imposes tailored previously undescribed solutions for the technique.

PATIENTS AND METHODS

Herein, three cases of high output duodenal fistula successfully treated with Negative Pressure Wound Therapy (NPWT) are reported. The technical details for the application of NPWT to these fistulas are discussed and described.

RESULTS

All three patients recovered without the necessity of further surgical operations.

CONCLUSIONS

When using NPWT, management of high-output duodenal fistulas must rely on some degree of customization of the aspiration systems. The aim of the procedure is to put under depression the duodenal hole and surrounding tissues "all in one" and not to separate the complex wound in sectors as usually indicated. We suggest calling this technique Negative Pressure Fistula Therapy.

Linear and nonlinear characteristics of the runoff response to regional climate factors in the Qira River basin, Xinjiang, Northwest China

The inland river watersheds of arid Northwest China represent an example of how, in recent times, climatic warming has increased the complexity of Earth’s hydrological processes. In the present study, the linear and nonlinear characteristics of the runoff response to temperature and precipitation were investigated in the Qira River basin, located on the northern slope of the Kunlun Mountains. The results showed that average temperature on annual and seasonal scales has displayed a significantly increasing trend, but this has not been reflected in accumulated precipitation and runoff. Using path analysis, a positive link between precipitation and runoff was found both annually and in the summer season. Conversely, it was found that the impact of temperature on runoff has been negative since the 1960s, attributable to higher evaporation and infiltration in the Qira River basin. Over the past 50 years, abrupt changes in annual temperature, precipitation and runoff occurred in 1997, 1987 and 1995, respectively. Combined with analysis using the correlation dimension method, it was found that the temperature, precipitation and runoff, both annually and seasonally, possessed chaotic dynamic characteristics, implying that complex hydro-climatic processes must be introduced into other variables within models to describe the dynamics. In addition, as determined via rescaled range analysis, a consistent annual and seasonal decreasing trend in runoff under increasing temperature and precipitation conditions in the future should be taken into account. This work may provide a theoretical perspective that can be applied to the proper use and management of oasis water resources in the lower reaches of river basins like that of the Qira River.

Quiet PROPELLER MRI techniques match the quality of conventional PROPELLER brain imaging techniques

BACKGROUND AND PURPOSE

Switching of magnetic field gradients is the primary source of acoustic noise in MR imaging. Sound pressure levels can run as high as 120 dB, capable of producing physical discomfort and at least temporary hearing loss, mandating hearing protection. New technology has made quieter techniques feasible, which range from as low as 80 dB to nearly silent. The purpose of this study was to evaluate the image quality of new commercially available quiet T2 and quiet FLAIR fast spin-echo PROPELLER acquisitions in comparison with equivalent conventional PROPELLER techniques in current day-to-day practice in imaging of the brain.

MATERIALS AND METHODS

Thirty-four consecutive patients were prospectively scanned with quiet T2 and quiet T2 FLAIR PROPELLER, in addition to spatial resolution-matched conventional T2 and T2 FLAIR PROPELLER imaging sequences on a clinical 1.5T MR imaging scanner. Measurement of sound pressure levels and qualitative evaluation of relative image quality was performed.

RESULTS

Quiet T2 and quiet T2 FLAIR were comparable in image quality with conventional acquisitions, with sound levels of approximately 75 dB, a reduction in average sound pressure levels of up to 28.5 dB, with no significant trade-offs aside from longer scan times.

CONCLUSIONS

Quiet FSE provides equivalent image quality at comfortable sound pressure levels at the cost of slightly longer scan times. The significant reduction in potentially injurious noise is particularly important in vulnerable populations such as children, the elderly, and the debilitated. Quiet techniques should be considered in these special situations for routine use in clinical practice.

Vacuum Assisted Closure (VAC) therapyTM as a swiss knife multi-tool for enteric fistula closure: tips and tricks: a pilot study

OBJECTIVE

Enterocutaneous fistulas (ECFs) are an uncommon surgical problem, but they are characterized by a difficult management. Vacuum-assisted closure (VAC) therapy is a method utilized for chronic and traumatic wound healing. At first, VAC therapy had been contraindicated in the treatment of intestinal fistulas, but as time went by, VAC therapy revealed itself to be a "Swiss knife multi-tool". This paper presents some clinical cases of enterocutaneous (ECF) and enteroatmospheric fistulas (EAF) treated with VAC therapy™.

MATERIALS AND METHODS

The history of 8 patients treated for complex fistulas was revised. Four of them presented with enterocutaneous and four with enteroatmospheric fistulas. All were treated with VAC therapy with variations elaborated to help in accelerated closure of intestinal wall lesions.

RESULTS

Four out of four ECFs closed spontaneously. In the EAF group, in three cases the fistula turned slowly into an entero-cutaneous fistula, and in one out of four it closed spontaneously. The mean length of VAC therapy™ was 35.5 days and that of spontaneous closure was 36.4 days.

CONCLUSIONS

The results of our study encourage the use of VAC therapy™ for the treatment of enterocutaneous fistulas. VAC therapy™ use has a double therapeutic value: (1) it promotes the healing of the skin and allows also the management of EAFs; (2) in selected cases, those in which it is possible to create a deep fistula tract ("well") it is possible to assist to a complete healing with closure of the ECFs.

Observational study on preoperative surgical field disinfection: povidone-iodine and chlorhexidine-alcohol

BACKGROUND AND OBJECTIVES

Surgical site infection (SSI) rate is reported to range around 16%. Preoperative skin disinfection is keystone for SSI reduction. Chlorhexidine-alcohol has been reported to be more effective than Povidone-iodine (PVI). However, in many countries established habits and the inferior costs of PVI restrain the employment of chlorhexidine disinfection kits (ChloraPrep®) for the preparation of the surgical field.

MATERIALS AND METHODS

The costs of surgical field preparation in clean-contaminated surgery utilizing PVI (Betadine) and chlorhexidine alcohol and the evaluation of surgeon compliance and satisfaction, were studied by a observational study on 50 surgical operations in which surgical field was prepared with PVI checking established guidelines, and on 50 surgical operations in which chlorhexidine-alcohol (ChloraPrep) was employed. The use of auxiliary material was tabulated as well as the timing of the phases of disinfection and the surgeon's opinions.

RESULTS

The use of auxiliary material (gloves, gauzes, paper towels, surgical instruments, small swabs for umbilical cleaning) is associated with the type of disinfectant, with major use of auxiliary materials recorded in PVI disinfection. PVI disinfection does not follow stringent guidelines, in particular waiting for the disinfectant to dry. PVI guidelines are more demanding than those relative to ChloraPrep. The time necessary for the preparation of the field is significantly longer for PVI. Auxiliary material and guideline compliance must be taken into account when calculating costs; the former are direct costs (even though marginal) and the latter can determine major infective risk.

CONCLUSIONS

Chlorhexidine in kits is easier and faster to use than PVI, requires less auxiliary material and has been shown previously to reduce SSI in clean contaminated surgery.

Characteristics of the clonal propagation of Alhagi sparsifolia Shap. (Fabaceae) under different groundwater depths in Xinjiang, China

Clonal reproduction of plants commonly occurs in arid areas because seedling establishment is rare in such severe environments. The features of clonal architecture differ not only among plant species but also within the same species growing in different environments. The characteristics of clonal propagation of Alhagi sparsifolia Shap. (Fabaceae), growing on the margins of Cele Oasis on the southern rim of the Taklamakan Desert, were investigated in September 2010. The study was conducted on three sites with different groundwater depths (2.5, 4.5, and 11.0 m). The results showed that the root suckering depth and the ability to expand and the biomass of coarse lateral roots of A. sparsifolia significantly increased when the groundwater depth increased. Moreover, the vegetative regeneration capacity of A. sparsifolia significantly declined with increasing groundwater depth, and the canopy cover at the site with a groundwater depth of 2.5 m was significantly greater than at the other two sites. There was no difference in aboveground biomass at the three sites. In such hyper-arid environments with a scarcity of soil nutrients, it was demonstrated that groundwater depth plays an important role in the clonal growth and propagation traits of A. sparsifolia. Increases in the groundwater depth as a result of over-use of oasis water for irrigation could lead to reduced populations of this important species in the interfaces between oases and the surrounding desert.

An economic evaluation of Clostridium difficile infection management in an Italian hospital environment

BACKGROUND AND OBJECTIVES

Clostridium difficile infection (CDI) accounts for the majority of nosocomial cases of diarrhea, and with recent upsurge of multidrug-resistant strains, morbidity and mortality have increased. Data on clinical impact of CDI come mostly from Anglo-Saxon countries, while in Italy only two studies address the issue and no economic data exist on costs of CDI in the in hospital setting. A retrospective cross-sectional study with pharmacoeconomic analysis was performed on the CDI series of the Policlinico Gemelli of Rome, a major 1400 bed Hospital.

PATIENTS AND METHODS

The clinical charts of 133 patients in a 26 month period were reviewed. All costs of the involved resources were calculated and statistical analysis was carried out with means and standard deviations, and categorical variables as number and percentages.

RESULTS

The results show the significant sanitary costs of CDI in an Italian hospital setting. The cost analysis of the various elements (exams, imaging studies, therapies, etc.) shows that none independently influences the high cost burden of CDI, but that it is the simple length of hospital stay that represents the most important factor.

CONCLUSIONS

Prevention of CDI is the most cost-effective approach. The major break-through in cost reduction of CDI would be a therapeutical intervention or procedure that shortens hospital length of stay.

The new retained foreign body! Case report and review of the literature on retained foreign bodies in laparoscopic bariatric surgery

The advent of laparoscopic surgery has created a set of peculiar morbidities. As the laparoscopic devices, also the type of retained foreign bodies has changed. We present a case of unusual, apparently isolated and recurrent lung abscess, pleural effusion and poorly evident subphrenic abscess after laparoscopic gastric bypass, due to a retained Endo-Catch bag. A 27-year-old obese female underwent an uneventful laparoscopic Roux-en-Y gastric bypass. After surgery she developed a left basal lung abscess, that resolved in two weeks with heavy antibiotic therapy, while radiological abdominal imaging was apparently normal. Patient was discharged on p.o. day 30. After two months, she presented with fever and dyspnoea and no gastrointestinal complaints. Chest and abdominal computer tomography showed a left recurrent abscess with effusion but this time a 3 cm subphrenic mass with metallic clips inside was demonstrated on CT scan. Patient was treated with an explorative laparoscopy that identified an Endo-Catch bag with the jejunal blind loop inside. Postoperative left lung abscess can be a warning of a suphrenic surgical complication. Laparoscopic surgery requires even more attention to retained foreign bodies due to the reduced visibility of the surgical field. The recommendation to enforce recording of laparoscopic maneuvers is mandatory.

Spectral reflectance properties of major objects in desert oasis: a case study of the Weigan-Kuqa river delta oasis in Xinjiang, China

Aiming at the remote sensing application has been increasingly relying on ground object spectral characteristics. In order to further research the spectral reflectance characteristics in arid area, this study was performed in the typical delta oasis of Weigan and Kuqa rivers located north of Tarim Basin. Data were collected from geo-targets at multiple sites in various field conditions. The spectra data were collected for different soil types including saline-alkaline soil, silt sandy soil, cotton field, and others; vegetations of Alhagi sparsifolia, Phragmites australis, Tamarix, Halostachys caspica, etc., and water bodies. Next, the data were processed to remove high-frequency noise, and the spectral curves were smoothed with the moving average method. The derivative spectrum was generated after eliminating environmental background noise so that to distinguish the original overlap spectra. After continuum removal of the undesirable absorbance, the spectrum curves were able to highlight features for both optical absorbance and reflectance. The spectrum information of each ground object is essential for fully utilizing the multispectrum data generated by remote sensing, which will need a representative spectral library. In this study using ENVI 4.5 software, a preliminary spectral library of surface features was constructed using the data surveyed in the study area. This library can support remote sensing activities such as feature investigation, vegetation classification, and environmental monitoring in the delta oasis region. Future plan will focus on sharing and standardizing the criteria of professional spectral library and to expand and promote the utilization of the spectral databases.

Effects of cutting and burning on regeneration of Alhagi sparsifolia Shap. on the southern fringe of the Taklamakan Desert, North-west China

Indigenous vegetation such as Alhagi sparsifolia Shap. (Fabaceae) has been severely damaged in recent years because of the growing population and increasing land use on the southern margin of the Taklamakan Desert. Alhagi sparsifolia plays an important role in supporting the fragile ecosystem in the oasis foreland as it has multiple ecological and economic functions. Cele Oasis, located on the southern rim of the Taklamakan Desert, was used to investigate the impact of human disturbance on regeneration of A. sparsifolia in the oasis–desert ecotone. Observations of A. sparsifolia in response to cutting and burning were conducted in 2010 and 2011. The results showed that burning in spring significantly decreased height and biomass in comparison to cutting in the fall. Moreover, biomass was decreased by spring burning more than by spring cutting. Burning in spring is no advantage for the growth and survival of A. sparsifolia. Cutting in fall appears to be a useful treatment for increasing the production from and survival of A. sparsifolia that could facilitate the sustainable development of the Cele Oasis.

Distribution pattern of plant species diversity in the mountainous region of Ili River Valley, Xinjiang

In this paper, detrended canonical correspondence analysis was performed to analyze the relationships between diversity indices and environmental gradients, generalized additive model was employed to modal the response curves of diversity indices to the elevation, based on data from field investigation in the mountainous region of the Ili River Valley and a survey of 94 sample plots. Two hundred fifty-nine plant species were recorded in the 94 sample plots investigated, up to 235 species all appeared in the herb layer, and the species of woody plants were very limited. The communities with a complicated vertical structure presented higher values of indices. The distribution pattern of plant species diversity on the northern slope was affected by such factors as elevation, slope aspect, slope gradient, total nitrogen, total potassium, soil water content, organic matter, and that on the southern slope was mainly affected by such factors as slope gradient, elevation, available phosphorus, and soil water content. On the northern slope, Patrick index and Shannon-Wiener index of the plant communities presented a bimodality pattern along altitude; Simpson index and Pielou index showed a partially unimodal pattern. On the southern slope all the distribution pattern of species diversity indices showed two peaks, though Patrick index's bimodality pattern was not an obvious one. These altitudinal patterns were formed by the synthetic action of a variety of environmental factors with elevation playing an important role.