Alternative rib bone biopsy measurements to estimate changes in skeletal mineral reserves in cattle

Rib bone biopsy samples are often used to estimate changes in skeletal mineral reserves in cattle but differences in sampling procedures and the bone measurements reported often make interpretation and comparisons among experiments difficult. ‘Full-core’ rib bone biopsy samples, which included the external cortical bone, internal cortical bone and trabecular bone (CB_ext, CB_int and Trab, respectively), were obtained from cattle known to be in phosphorus (P) adequate (P_adeq) or severely P-deficient (P_defic) status. Experiments 1 and 2 examined growing steers and Experiment 3 mature breeder cows. The thickness of cortical bone, specific gravity (SG), and the amount and concentration of ash and P per unit fresh bone volume, differed among CB_ext, CB_int and Trab bone. P concentration (mg/cc) was closely correlated with both SG and ash concentrations (pooled data, r=0.99). Thickness of external cortical bone (CBT_ext) was correlated with full-core P concentration (FC-P_conc) (pooled data, r=0.87). However, an index, the amount of P in CB_ext per unit surface area of CB_ext (PSACB; mg P/mm²), was more closely correlated with the FC-P_conc (pooled data, FC-P_conc=37.0+146×PSACB; n=42, r=0.94, RSD=7.7). Results for measured or estimated FC-P_conc in 10 published studies with cattle in various physiological states and expected to be P_adeq or in various degrees of P_defic status were collated and the ranges of FC-P_conc indicative of P adequacy and P deficiency for various classes of cattle were evaluated. FC-P_conc was generally in the range 130 to 170 and 100 to 120 mg/cc fresh bone in P_adeq mature cows and young growing cattle, respectively. In conclusion, the FC-P_conc could be estimated accurately from biopsy samples of CB_ext. This allows comparisons between studies where full-core or only CB_ext biopsy samples of rib bone have been obtained to estimate changes in the skeletal P status of cattle and facilitates evaluation of the P status of cattle.     

Effects of benzyl alcohol on phosphatidylcholine lamellar phase with different water contents

Effects of benzyl alcohol (BA) on the bilayer thickness d₁ and the fluidity of egg phosphatidylcholine (PC) lamellar phase with various water contents have been studied by X-ray diffraction and the proton spin-lattice relaxation rate. At lower water contents; BA causes d₁ to decrease and the rate of molecular motions to increase. By contrast, with increasing BA at excess water, d₁ remains nearly unchanged, though the rate of motions increases. Hydration experiment for egg phosphatidylcholine lamellae with BA at a 1:1 molar ratio shows that in the range from 15% to 30% water, d₁ decreases to the value of the fully hydrated sample without BA and is nearly constant above 30% water. The value at full hydration is suggested to be a lower limit of the bilayer thickness, the chain is in the unperturbed state. It is in an extended structure at lower water contents. This leads to the difference in the effect of BA on the bilayer thickness at different water contents.     

Influence of larval outbreaks on the climate reconstruction potential of an Arctic shrub

Arctic shrubs have a strong potential for climate and environmental reconstructions in the chronically understudied regions of the high northern latitudes. The climate dynamics of these regions are important to understand because of large-scale feedbacks to the global climate system. However, little is known about other factors influencing shrub ring growth, possibly obscuring their climate signal. For example, as of yet we are not able to differentiate between herbivory or climatically induced growth depressions. Here, we use one of the most common Arctic shrubs, Alnus viridis as a test case to address this question. We sampled Alnus in Kobbefjord, Greenland, measured shrub-ring width and cell wall thickness and built site chronologies of each parameter. We analysed climate-growth relationships, tested their stability over time and employed a pointer-year analysis to detect growth depressions. We employed bootstrapped transfer function stability tests (BTFS) to assess the suitability of our shrub chronologies for climate reconstruction. Correlations with climate data showed strong significantly positive and stable correlations between summer temperature and ring-width with the exception of the recent decade. A climate reconstruction model failed stability tests, when the complete period of record was used for calibration and verification. Wood anatomy analysis uncovered the occurrence of unusual cell structure (very thin cell walls) in the exceptionally narrow ring of 2004, a recorded insect outbreak year in other parts of Greenland. When excluding the affected ring and a recovery period, the reconstruction model passed all tests, suggesting that the unusual 2004 ring was not climate driven, but rather the result of an insect attack. When combining anatomical analysis with traditional ring-width measurements, we move a step further in potentially distinguishing small rings caused by insect attacks from small rings formed in climatically challenging years. While this study does not provide unambiguous evidence, it does provide potential useful methodological combinations to enable more robust climate reconstructions in areas where climatic records are extremely sparse.     

Photosynthesis of herbaceous plants from nutrient-poor tropical forests

Photosynthetic characteristics, specific leaf mass, chlorophyll and total leaf nitrogen concentrations of four herbaceous plants (Dicranopteris linearis, Hanguana malayana, Pentaphragma ellipticum, Tacca integrifolia) from nutrient-poor tropical forests showed that all these plants were well-adapted to their natural growth environments. No photoinhibition was observed even in the understorey plants. This revised version was published online in June 2006 with corrections to the Cover Date.     

Research progress on monitoring vegetation water content by using hyperspectral remote sensing

植被含水量是陆地植被重要的生物物理特征, 其定量遥感反演有助于植被干旱胁迫的实时监测与诊断评估。该文系统综述了国内外利用高光谱遥感评估植被水分状况的4个常见植被水分指标——冠层含水量、叶片等量水厚度、活体可燃物湿度和相对含水量的概念及其遥感估算方法研究进展, 评述了植被含水量高光谱遥感估算各类方法的优缺点, 探讨了植被含水量高光谱遥感估算目前存在的问题, 并提出进一步的研究任务, 即服务于植被干旱胁迫的高光谱遥感监测、预警与评估。     

延展与解蔽—基于时空体验的景观与建筑的内外交互

基于时空关系与体验,探讨了景观与建筑的交接空间。对其建构方式与体验感知方式进行研究。基于戴维·哈维（David Harvey）的“时空压缩”以及希格弗莱德·吉迪恩（Sigfried Giedion）的“空间时间”理论,通过诠释“厚性”的概念,分析了景观与建筑空间交接的2种基本出发点：基于时空拉伸的“延展”,以及基于时空压缩的“解蔽”;通过案例研究,对其不同的空间组织方法与空间界定材料的使用方式进行解读,并论述与此对应的2种空间感知过程：“可推导性”与“瞬时生成性”;通过分析4个现当代景观实践案例,对景观设计在空间“内外交互”建构中所发挥的主动性与使用方法进行综合研究。最后,对时空建构的基本方法、综合使用等方面进行应用层面的分类与总结。     

Two optical coherence tomography systems detect topical gold nanoshells in hair follicles,sweat ducts and measure epidermis

Optical coherence tomography (OCT) is an established imaging technology for in vivo skin investigation. Topical application of gold nanoshells (GNS) provides contrast enhancement in OCT by generating a strong hyperreflective signal from hair follicles and sweat glands, which are the natural skin openings. This study explores the utility of 150 nm diameter GNS as contrast agent for OCT imaging. GNS was massaged into skin and examined in four skin areas of 11 healthy volunteers. A commercial OCT system and a prototype with 3 μm resolution (UHR‐OCT) were employed to detect potential benefits of increased resolution and variability in intensity generated by the GNS. In both OCT‐systems GNS enhanced contrast from hair follicles and sweat ducts. Highest average penetration depth of GNS was in armpit 0.64 mm ± SD 0.17, maximum penetration depth was 1.20 mm in hair follicles and 15 to 40 μm in sweat ducts. Pixel intensity generated from GNS in hair follicles was significantly higher in UHR‐OCT images (P = .002) and epidermal thickness significantly lower 0.14 vs 0.16 mm (P = .027). This study suggests that GNSs are interesting candidates for increasing sensitivity in OCT diagnosis of hair and sweat gland disorders and demonstrates that choice of OCT systems influences results.