Soil and erosion features of the central plateau region of Tigrai,Ethiopia

The results of reconnaissance soil surveys covering 6,000 km² are used to describe the Central Plateau region, which lies at elevations of 2,000 to 2,800 m in northern Ethiopia. Landform and soil sequences on calcareous shales, dolerites and sandstones are described, in which the principal soil units are Lithosols, Luvisols, Cambisols, Arenosols and Vertisols. Detailed morphological and analytical data are presented for a profile representative of arable soils in each sequence.Small-scale subsistence cultivation of cereals is the dominant land use; all land which is physically cultivable is at present cultivated. Settlement patterns are closely related to soil type, nucleated settlement occurring on fine textured soils but dispersed settlement on coarser textured and more freely draining soils.Erosion and soil moisture features of the three landforms described were investigated and compared. Empirical methods and suspended sediment measurements indicate high rates of regional soil loss (17–33 t ha^?1 yr^?1), accounted for by seasonally high rates of rainfall erosivity, steep terrain and poor land use. The recent development of gully erosion is seen to be linked to the disintegration of waterfall tufas. Application of the universal soil loss equation to arable lands indicates potential annual soil losses in the range of 400 t ha^?1 on Vertisols to 200 t ha^?1 on Cambisols: differences in rates are ascribed principally to differences in crop planting dates, which affect the degree of vegetative protection during periods of high rainfall erosivity.Soil moisture is shown to be in the available range for less than three months in the year. The time at which moisture in the profile enters the available range differed between the three soils monitored and was found to be closely related to the crop planting date, thus indirectly affecting the erosion hazard.     

The vexatious problem of the variation of the phyllochron in wheat

Measurements of the thermal phyllochron in wheat using air temperature show a systematic variation with sowing date, with long phyllochrons for crops sown in autumn and winter, but shorter phyllochrons for sowings outside that range. Based on the hypothesis that the phyllochron is constant, two sources of error for the apparent variation in phyllochron are investigated, namely the site of temperature measurement (air or soil) and the implicit assumption that leaf appearance rate responds linearly to temperature. Measurements of the phyllochron from three sowings per annum for 6 years, from controlled environments, and from a sequence of sowings through an annual cycle are presented. The field results show similar systematic variation to that found elsewhere. However, for the annual cycle, calculations of the phyllochron based on soil temperature at 2 cm depth were much more stable than those based on air temperature. In addition, leaf appearance rate was linearly related to 2 cm soil temperatures across all environments, with a 0 °C intercept, and the optimum temperature was still not reached in the highest temperature treatment (30.9 °C soil temperature). Following earlier published work, we then show that the assumption that the phyllochron is constant, but that the controlling temperature at the apex is different from air temperature, requires a correction of less than 1 °C when sowing dates do not stray too much outside the range of normal practice. We show that the correction to air temperature is systematically related to sowing date, and a suitable correction can be made by using daylength some time after emergence as a predictive surrogate for seasonal variation in the air–apex temperature difference. We suggest that a model using such a predictor will improve predictions of leaf appearance rate over earlier functional models. However, we suggest that the observed response is caused by the physics of the system rather than the biology.     

论高校图书馆流通服务中的＂关键时刻＂管理

分析了高校图书馆流通服务和赢利性企业的共性,论述了高校图书馆流通服务管理应用“关键时刻”管理理论的可行性和必要性。提出了通过对高校图书馆流通服务中的一系列“关键时刻”的强化管理．提高流通服务质量,最大限度地满足读者需求的策略。     

From saving to survivance: Rethinking Indigenous Papuan women's vulnerabilities in Jayapura,Indonesia

Racism, sexism and gendered violence disadvantage Indigenous Papuan women, yet government responses often focus on individual interventions like ‘raising awareness’ or training. In this article, we build on efforts to challenge these narratives about women's vulnerabilities. We draw on life history interviews with older Papuan women in Jayapura to rethink vulnerabilities and everyday struggles in the context of structural inequalities. We interpret their stories as forms of ‘survivance’ and argue that contrary to dominant perspectives, Papuan women are not economic novices or passive victims. Rather, opportunities have narrowed over time, and women's long history of activity, strategy, persistence and resistance has largely been forgotten. Women's life histories shed light on urban colonialism and Indigenous survivance in Jayapura since the 1940s, when Jayapura was still a Dutch colonial capital and not yet an Indonesian frontier. In a time dominated by concerns about Papuan demise, their experiences are provocative for rethinking vulnerabilities.     

A comparison between non-destructive and destructive testing of Atlantic salmon, Salmo salar L., broodfish for IPNV--destructive testing is still the best at time of maturation.

Two populations of Atlantic salmon broodstock, previously identified as infectious pancreatic necrosis virus (IPNV) carriers, were screened for IPNV at the time of stripping. Four hundred and ten broodfish were individually sampled of which 91 were detected as IPNV positive by virus culture of sonicated kidney homogenates combined with gonadal fluid, but none tested positive by the blood leucocyte assay. Thirty fish identified as IPNV carriers prior to maturation by the blood leucocyte assay were used in a separate study to compare non-destructive vs. destructive testing methods at stripping. IPNV was not detected using the blood leucocyte method at the time of stripping. RT-PCR and real-time PCR assays failed to detect IPNV from 13 blood samples, the virus was not isolated from milt (0/14) or sonicated ovarian fluid cell pellets (0/16) and only three fish tested positive by the standard culture of kidney homogenates. A third study of Atlantic salmon broodfish compared the IPNV isolation rates prior to maturation with the isolation rates at spawning during 1999-2001. In each year the percentage of IPNV-positive broodfish was significantly lower than in the pre-broodstock sample. While in pre-broodfish samples IPNV was detected by the blood leucocyte assay, no culture isolations or PCR positives were detected from non-destructive samples of the same individual broodfish at stripping. A consistent finding was that even for the kidney assay, the percentage of IPNV-positive fish in carrier populations was higher in pre-broodstock than in broodfish at stripping. These results indicate that destructive kidney sampling is still the most sensitive method for detecting IPNV carrier Atlantic salmon broodfish and that a change in IPNV carrier-status occurs during the maturation period.     

Thermal Characterization of Alkali Treated Kenaf Fibers and Kenaf-Epoxy Composites

Chemical treatment of natural fibers is a well-defined means of mechanical property improvement in natural fiberreinforced composites. An understanding of mechanical and thermal properties in these media is essential for evaluating heat transfer, thermal degradation, and overall performance of these composites over their product lifetime. However, very little information is available illustrating the effect of such treatment on the thermal properties of kenaf composites. Also, no study to date has reported the thermal conductivity of individual kenaf fibers. This study reports the effects of fiber treatment (in 6 % NaOH) on thermal transport in unidirectionally oriented kenaf-epoxy composites and individual kenaf fibers. The effective thermal conductivities and thermal diffusivities of chemically treated fiber composites show a general increase over untreated fiber composites (0.210 to 0.232 W/m/K at 28 °C, 0.206 to 0.234 W/m/K at 200 °C). This improvement may be attributed to improved interfacial contact between the fibers and epoxy matrix shown in microstructural images after chemical treatment. The thermal conductivity of individual fibers was evaluated at room temperature using two techniques. Results from both techniques showed slight increases after chemical treatment (0.58±0.53 to 1.0±0.13 W/m/K and 1.2±0.54 to 1.6±0.28 W/m/K) but lacked statistical significance. Any improvement in surface crystallinity after chemical treatment does not appear to affect overall fiber thermal conductivity. A better understanding of thermal transport in kenaf fibers and composites enables better estimation of the performance of these composites in different applications. Moreover, the thermal conductivities of individual fibers are useful in understanding the fiber’s contribution to conduction in different fiber reinforcement configurations.