基于小波滤波与自适应阈值分割算法的玫瑰叶片病斑提取研究

针对玫瑰叶片白粉病病斑分布离散、无序且边缘细节复杂、传统图像分割算法提取病斑困难等问题,提出了一种基于小波滤波与自适应均值阈值分割（WT-AAT）的叶片病斑图像提取算法。首先,为了去除原始图像噪声,使用二维离散哈尔小波变换将图像进行二层小波分解,并依据高、低频子图像自动提取噪声系数,进而设定滤波阈值;然后,将高于阈值的噪声系数置零,并逆序对每层进行小波重构,最终生成等尺度的去噪图像;最后,采用可滑动窗口分割算法对去噪图像进行自适应分割,再根据子图的灰度均值设定二值化阈值,在二值化处理的基础上析取白粉病病斑。结果表明,与WaterShed、Prewitt、Otsu等传统分割算法相比,WT-ATT的像素漏警率的降低率分别为18%、18%和6%,说明该方法能够较为准确地分割出病斑,并达到良好的病斑辨识效果。     

Global warming, elevational range shifts, and lowland biotic attrition in the wet tropics

Many studies suggest that global warming is driving species ranges poleward and toward higher elevations at temperate latitudes, but evidence for range shifts is scarce for the tropics, where the shallow latitudinal temperature gradient makes upslope shifts more likely than poleward shifts. Based on new data for plants and insects on an elevational transect in Costa Rica, we assess the potential for lowland biotic attrition, range-shift gaps, and mountaintop extinctions under projected warming. We conclude that tropical lowland biotas may face a level of net lowland biotic attrition without parallel at higher latitudes (where range shifts may be compensated for by species from lower latitudes) and that a high proportion of tropical species soon faces gaps between current and projected elevational ranges.     

Amyloid fibrils of the HET-s(218-289) prion form a beta solenoid with a triangular hydrophobic core

Prion and nonprion forms of proteins are believed to differ solely in their three-dimensional structure, which is therefore of paramount importance for the prion function. However, no atomic-resolution structure of the fibrillar state that is likely infectious has been reported to date. We present a structural model based on solid-state nuclear magnetic resonance restraints for amyloid fibrils from the prion-forming domain (residues 218 to 289) of the HET-s protein from the filamentous fungus Podospora anserina. On the basis of 134 intra- and intermolecular experimental distance restraints, we find that HET-s(218-289) forms a left-handed beta solenoid, with each molecule forming two helical windings, a compact hydrophobic core, at least 23 hydrogen bonds, three salt bridges, and two asparagine ladders. The structure is likely to have broad implications for understanding the infectious amyloid state.     

Sources and distribution of arsenic in agricultural soils of Central Mexico

Purpose

The concentrations and distribution of arsenic (As) in two different soil types (Vertisols and Entisols) of Central Mexico impacted by mine activities and irrigation with As-rich groundwater are analyzed in order to determine their impact on the soil quality, and to contribute reliable data that may help to assess the environmental risk that represents the progressive accumulation of As in the arable soils of Guanajuato.

Materials and methods

Two Entisol and two Vertisol profiles located in the Guanajuato state (Mexico) were described and sampled from ~?1.20-m-deep pits. Soils are irrigated with As-rich deep and shallow groundwaters that were sampled from irrigation boreholes. Additionally, a Vertisol profile located in a parcel not impacted by irrigation was sampled and used as a control soil. Minerals were identified by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with dispersive X-ray spectrometry (EDS). Geoaccumulation indexes (Igeo) were calculated to evaluate As enrichment with respect to a control soil and the Upper Continental Crust (UCC). Anions and cations of groundwater were analyzed by high-performance liquid chromatography (HPLC) and by inductively coupled plasma atomic emission spectroscopy (ICP-AES), respectively. As in soils was determined by ICP-AES.

Results and discussion

Near total As concentrations are higher in Entisols (mean As value?=?7.20 mg/kg) than in Vertisols (mean As?=?1.02 mg/kg). As concentrations in the control soil are lower (0.34 to 0.70 mg/kg). The in-depth distribution of As in Vertisol profiles reveals that the higher As concentrations are found in the uppermost horizons (10 cm) and they tend to decrease with depth. In Entisols, As concentrations do not follow a vertical trend. Igeo values of As indicate moderate to heavy As contamination in Vertisols and moderate contamination in Entisols. SEM-EDS analyses revealed the presence of some potential As-bearing minerals such as magnetite and abundant Fe oxides and Ti-Fe coatings precipitated onto feldspar grains, particularly in Entisols.

Conclusions

Irrigation of Vertisols with As-rich groundwater determines As concentrations in the uppermost horizons that exceed the natural background of the region (0.4 mg/kg). In depth, clay grain-sized particles inhibit the downward migration of As, while Fe oxides and organic matter scavenge As by adsorption. As concentrations in Entisols are higher, and the in-depth distribution of this element is controlled by periodic contributions of As-bearing minerals delivered from mine prospects located at the river’s catchments.

     

Technical and Economic Analysis of Aeroponics and other Systems for Potato Mini-Tuber Production in Latin America

Producing large quantities of high quality mini-tubers at low cost is essential for an economically viable supply of seed potatoes. Here we systematize the technical and economic aspects of aeroponics and provide a benchmark comparison of this technology with other mini-tuber production systems as developed in Latin America: conventional, semi-hydroponics, and fiber-cement tiles technology. Research methodologies included: 3-year registration of cash flows and production registers of aeroponics, economic and technical surveys, in-depth inquiry with managers of technologies. Results show that aeroponics as promoted by the International Potato Center (CIP) has several advantages, including high multiplication rates (up to 1:45), high production efficiency per area (> 900 mini-tubers per m²), savings in water, chemicals and/or energy, and positive economic indicators. The fiber-cement tiles technology from Brazil is also shown to be highly efficient and slightly more robust compared to aeroponics. Preconditions for the successful adoption of the different technologies in developing countries are discussed.     

The Effects of the Decaffeination of Coffee Samples on Platelet Aggregation in Hyperlipidemic Rats

The effect of coffee on cardiovascular diseases is still controversial. It is known that the process of decaffeination may influence the chemical constitution and, therefore, the biological effects of coffee. This study thus evaluated the effects of decaffeination on the levels of total phenols and chlorogenic acids in Coffea arabica L. samples, as well as the effects of ingesting both integral and decaffeinated coffee on the lipid profile and hemostatic and hematological parameters in normal and hyperlipidemic rats. Samples of integral and decaffeinated lyophilized coffee (Coffea arabica L., planted in Brazil) were used for chemical analysis (total phenols, chlorogenic acid and caffeine contents). For the bioassays, coffee beverages were prepared with non-lyophilized samples (10 % w/v) and were filtered and administered to animals by gavage (7.2 mL/kg/day) over 30 days. On the 31st day after beginning the treatment with coffee beverages, hyperlipidemia was induced to the animals by administering Triton WR-1339 (300 mg/kg body weight). On day 32, blood was taken to determine the lipid profile, platelet aggregation, prothrombin time, partially activated thromboplastin time and hemogram. The contents of both phenolic compounds and chlorogenic acid in the integral coffee beverage were significantly lower than those in the decaffeinated coffee beverage. The animals treated with Triton WR-1339 presented a mixed hyperlipidemia. Although the decaffeination process caused a relative increase in total phenols and chlorogenic acids, the coffee drinks were unable to change the lipid profile or the hemostatic and hematological parameters in the studied animals.     

A Sulfated-Polysaccharide Fraction from Seaweed Gracilaria birdiae Prevents Naproxen-Induced Gastrointestinal Damage in Rats

Red seaweeds synthesize a great variety of sulfated galactans. Sulfated polysaccharides (PLSs) from seaweed are comprised of substances with pharmaceutical and biomedical potential. The aim of the present study was to evaluate the protective effect of the PLS fraction extracted from the seaweed Gracilaria birdiae in rats with naproxen-induced gastrointestinal damage. Male Wistar rats were pretreated with 0.5% carboxymethylcellulose (control group—vehicle) or PLS (10, 30, and 90 mg/kg, p.o.) twice daily (at 09:00 and 21:00) for 2 days. After 1 h, naproxen (80 mg/kg, p.o.) was administered. The rats were killed on day two, 4 h after naproxen treatment. The stomachs were promptly excised, opened along the greater curvature, and measured using digital calipers. Furthermore, the guts of the animals were removed, and a 5-cm portion of the small intestine (jejunum and ileum) was used for the evaluation of macroscopic scores. Samples of the stomach and the small intestine were used for histological evaluation, morphometric analysis and in assays for glutathione (GSH) levels, malonyldialdehyde (MDA) concentration, and myeloperoxidase (MPO) activity. PLS treatment reduced the macroscopic and microscopic naproxen-induced gastrointestinal damage in a dose-dependent manner. Our results suggest that the PLS fraction has a protective effect against gastrointestinal damage through mechanisms that involve the inhibition of inflammatory cell infiltration and lipid peroxidation.     

Correction to: Breeding and scientific advances in the fight against Dutch elm disease: Will they allow the use of elms in forest restoration?

New Forests - Author had ordered for open access after the article went online in Springer link. The article was changed to open access article.     

冬小麦预留套行种植模式的超高产生育规律研究

为揭示冬小麦预留套行种植模式的增产机理,以新冬20为材料,以不留套行为CK,在大田条件下系统研究了9行麦空5行(9-5)、5行麦空2行(5-2)两种模式冬小麦的生育规律及茎数、叶面积等的边际效应。结果表明,5-2模式的总茎数、叶面积、干物质积累、产量的边际效应为11.3%～36.0%,远低于9-5模式的57.8%～103.0%,但5-2模式各行茎数、叶面积、干物质积累和籽粒产量等性状较CK有明显改善,籽粒产量达到9 968.7kg.hm-2,较CK增产11.25%。5-2模式产量结构为穗数679.6万.hm-2、穗粒数36.79、千粒重40.75g;最高总茎数达到1 578.7万.hm-2,成穗率为44.2%,最大叶面积指数6.22,总干物质积累量18 124.9kg.hm-2,经济系数0.55。5-2模式各生育时期的茎数、叶面积、干物质积累等边际效应所导致的产量边际效应超补偿了2空行的产量损失,有利于实现冬小麦超高产。     

Effects of Drying Process on the Physicochemical Properties of Nopal Cladodes at Different Maturity Stages

Chemical proximate analysis was done in order to determine the changes of nutritional characteristics of nopal powders from three different maturity stages 50, 100, and 150 days and obtained by three different drying processes: freeze dried, forced air oven, and tunnel. Results indicate that nopal powder obtained by the process of freeze dried retains higher contents of protein, soluble fiber, and fat than the other two processes. Also, freeze dried process had less effect on color hue variable. No changes were observed in insoluble fiber content, chroma and lightness with the three different drying processes. Furthermore, the soluble fibers decreased with the age of nopal while insoluble fibers and ash content shows an opposite trend. In addition, the luminosity and hue values did not show differences among the maturity stages studied. The high content of dietary fibers of nopal pad powder could to be an interesting source of these important components for human diets and also could be used in food, cosmetics and pharmaceutical industry.