Assessment of the properties,utilization, and preservation of rubberwood (<Emphasis Type="Italic">Hevea brasiliensis</Emphasis>): a case study in Malaysia

Rubber trees were introduced into the Malay Peninsula more than a century ago. The normal economical lifespan of a rubber tree is about 25 years, and, traditionally, rubberwood was used as firewood by the rural community. In recent decades, rubberwood has become an important timber for wood products, particularly in the furniture manufacturing sector, due to its attractive features, cream color, and good working properties. Sapstain, mold, and wooddecaying fungi are serious threats to rubberwood. Conventional chemical control has been a successful method of preventing staining fungal growth, but the effects of these chemicals are of concern because they create problems for the environment and public health. Thus, biological control has been recognized as an alternative approach to the problem. This article reviews the properties, potential utilization, and problems of protecting rubberwood against sapstain, mold, and wood-decaying fungi, and discusses the treatment methods available. Advances in biological control, particularly biofungicides, are emphasized as an alternative method for rubberwood treatment.     

Movement of bacteria and nutrients from pit latrines in the boundary waters canoe area wilderness

In the Boundary Waters Canoe Area Wilderness, the movement of fecal bacteria, N, and P from pit latrines was studied, as well as the effectiveness of peat latrine liners in reducing this movement. When latrines are constructed where only a thin layer of permeable soil overlies bedrock or other impermeable material, fecal bacteria can be carried considerable distances by subsurface flow. Lining latrine pits with acid peat appears to reduce bacteria transport. Most soils strongly adsorb P and prevent its movement. In this study no movement of P from latrine pits was seen except at one site with very sandy soil. In such soil a peat liner appears to be of some value, if a peat with a high P adsorption capacity is used. A peat liner should be viewed as an additional protection against P and bacteria movement rather than as a substitute for proper soil conditions. Latrines should not be built in thin, rocky soils. Nitrogen appears to move readily from toilet pits, regardless of soil type or presence of peat liners. But, because of dilution, N is not likely to have a discernible impact on water quality.     

Modelling effectiveness of herd level vaccination against Q fever in dairy cattle

ABSTRACT: Q fever is a worldwide zoonosis caused by the bacterium Coxiella burnetii. The control of this infection in cattle is crucial: infected ruminants can indeed encounter reproductive disorders and represent the most important source of human infection. In the field, vaccination is currently advised in infected herds but the comparative effectiveness of different vaccination protocols has never been explored: the duration of the vaccination programme and the category of animals to be vaccinated have to be determined. Our objective was to compare, by simulation, the effectiveness over 10 years of three different vaccination strategies in a recently infected dairy cattle herd.A stochastic individual-based epidemic model coupled with a model of herd demography was developed to simulate three temporal outputs (shedder prevalence, environmental bacterial load and number of abortions) and to calculate the extinction rate of the infection. For all strategies, the temporal outputs were predicted to strongly decrease with time at least in the first years of vaccination. However, vaccinating only three years was predicted inadequate to stabilize these dynamic outputs at a low level. Vaccination of both cows and heifers was predicted as being slightly more effective than vaccinating heifers only. Although the simulated extinction rate of the infection was high for both scenarios, the outputs decreased slower when only heifers were vaccinated.Our findings shed new light on vaccination effectiveness related to Q fever. Moreover, the model can be further modified for simulating and assessing various Q fever control strategies such as environmental and hygienic measures.     

Unsteady state two-dimensional water content distribution and wetting fronts in soils

The unsteady state two-dimensional water flow equation for unsaturated soils was solved numerically with the aid of an alternating-direction implicit method. Water content distributions, wetting fronts, and water flux were predicted for an Ida silt loam soil with an impermeable barrier and a Webster clay loam soil with a groundwater table. It is concluded that the numerical method is stable and convergent for solving unsteady state two dimensional infiltration problems.     

A multi-metric index for assessing two decades of community responses to broad-scale shoreline enhancement and restoration along the Toronto waterfront

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Targeted identification of association between cotton fiber quality traits and microsatellite markers

Primitive and exotic accessions of cotton are potential sources of favorable alleles for genetic improvement, enriching diversity in the genetically constricted gene pool of elite cultivars. Three exotic accessions of cotton (MDN101, MDN063 and MDN257), collected from different parts of Central America and converted to day-neutral flowering; and four elite cultivars (PD94042, DES56, PMHS200 and Acala Maxxa) representing the US cotton gene pool were used as parents to create experimental populations. The corresponding F₂ and F_2:3 progenies of these populations were grown in two successive years (i.e., some in 2011–2012, some in 2012–2013) and phenotypes were scored in both F₂ and F_2:3 progenies in all 3 years (2011–2012–2013). These populations were screened with 113 polymorphic microsatellite markers selected from “hotspots” for fiber quality quantitative trait loci in the cotton genome and single marker analyses were performed to identify significant associations of the markers with six fiber quality traits. A total of 134 nominal marker-trait associations were identified, among which 15 were significant after Bonferroni correction for multiple comparisons. In 67 of 134 nominal associations and 4 of 15 significant associations, the exotic parents contributed favorable alleles to multiple backgrounds and for multiple traits, in addition to the traits for which they were selected. These results indicate that utilization of exotic and wild accessions of cotton is useful in introducing favorable alleles into the cultivated cotton gene pool for genetic improvement.     

母猪矿物质储备的损耗——如何满足高产母猪对矿物质的营养需要

高产母猪对矿物质的需要尚不是很明确.迄今为止的研究证实,随着胎次的增加,母猪体内的常量元素和微量元素储备逐渐减少,而且高繁殖力还加剧矿物质的丢失.母猪的繁殖周期中有些时期(通常是妊娠后期和哺乳阶段)对常量元素和微量元素的需要量很高,但这些元素在其它时期也同样非常重要.然而简单地增加母猪饲粮中的常量元素和微量元素的含量可能并不是理想的方法,因为这种方法可能降低母猪的繁殖性能.近期的研究表明,有机微量元素能提高母猪6胎以上的窝产仔数.已有研究表明,虽然有机硒具有提高母猪繁殖性能的功效,但其它微量元素可能也在提高母猪繁殖性能方面发挥了相应的作用.     

如何满足高产母猪对矿物质的营养需要

<正>高产母猪对矿物质的需要量尚不是很明确。迄今为止的研究证实,随着胎次的增加,母猪体内的常量和微量元素储备逐渐减少,而且高繁殖力还加剧矿物质的丢失。母猪的繁殖周期中,某些时期(通常是怀孕后期和哺乳阶段)对常量和微量元素的需要     

The phosphorus status of German cropland—An inventory of top‐ and subsoils

Background : In search for more sustainable crop production, the subsoil has recently come into focus as considerable reservoir of nutrients and water. Aims : Dimensions of subsoil phosphorus (P) reserves are yet largely unknown but crucial for identifying regions suitable to include subsoil into sustainable management strategies. Methods : We analyzed stocks of total and plant‐available (calcium acetate lactate‐extractable) P in 96 representative soil profiles of German arable land down to 1 m depth. Results : We found that the German arable soils stored, on average, 8 t ha^?1 of total P, of which nearly 500 kg ha^?1 were readily plant‐available. Notably, one third of plant‐available P was located below the plow layer and one fifth even at depths below 0.5 m. The depth gradients of plant‐available P stocks were affected more by major reference soil group than by texture. Generally, Chernozem but also Anthrosol, Gleysol and Fluvisol exhibited the largest P stocks in German cropland. The contribution of plant‐available P to total P stocks was larger in sandy and extremely acidic (pH < 4.5) soils compared with more fine‐grained and slightly acidic to alkaline soils, possibly because fertilization compensated for overall lower total P stocks at these sites. Generally, the more P was stored in topsoils, the more P was stored also in subsoils. Conclusions : A hypothetical crop utilization of 10% from plant‐available P stocks and 0.1% from total P stocks from shallow subsoil could compensate for P fertilization by ca. 8 kg ha^?1, but the rate of plant‐available P replenishment in subsoil likely remains the crucial factor for the role of subsoil P stocks in crop nutrition. Generally, the large P reserves found in subsoil could act as an ‘insurance' system for crops.     

七株旋毛虫几项生物学特性的比较研究

对采自我国哈尔滨、长春、天津、西安、河南邓县、新野及云南保山的７株旋毛虫的成虫形态及幼虫在肌组织中寄生、成囊等作了比较研究。原始虫株除长春株采自犬外，其余６林原始宿主均为猪。虫株用大白鼠及小白鼠继代。结果表明，７个虫株在光镜形态学上无差异，但长春犬株３日龄及７日龄成虫的大小明显小于其它６个虫株，对小白鼠的感染性较低，幼虫卷曲、成囊均较晚，而且幼虫有钙化、死亡现象。