Effects of tree spacing on branch-size development during early growth of an experimental plantation of Eucalyptus pilularis in subtropical Australia

ABSTRACT

Branch development in trees 1.6–5.7 years after planting was studied in a plantation experiment involving Eucalyptus pilularis in subtropical eastern Australia. The experiment compared stocking densities at planting in the range of 816–1667 stems ha^?1 and rectangularities of tree spacing in the range of 1–6. Branch diameters at their bases were measured on the lowest 5 m of the stems of trees judged likely to yield sawn timber of high quality at final harvest. Neither stocking density nor rectangularity had substantial effects on branch numbers or diameters. Particular interest was paid to the presence of branches with diameters in excess of 2.5 cm that might produce knots large enough to degrade the quality of sawn timber. Such branches developed on lower stems between 2–4 years of age. An average of nearly five such branches was found on more widely spaced trees, reducing to 2–3 on more closely spaced trees. The results confirmed other work suggesting that pruning of high-quality eucalypt plantations should start near 2–3 years of age to both limit the development of large branches and restrict the size of knotty cores in logs. There was no evidence that changing the rectangularity of spacing to 3 or a little more, from the more normal practice of close to square, would affect such pruning regimes: increasing the distance between rows can reduce establishment and harvest costs and allow easier access for silvicultural operations.     

The effect of tree spacing on the production of flowers in Eucalyptus nitens

The effect of spacing on the production of flowers and capsules in Eucalyptus nitens was studied in two spacing trials located in northern Tasmania. Tree density in these trials ranged from 468 to 4216 stems ha^?1. Reproductive structures were collected in litter traps and these data were used to calculate reproductive output on a per tree and per hectare basis. Between 8735 (5-y-old site, 1333 stems ha”¹) to 234098 (13-y-old site, 1082 stems ha”¹) flowers were produced per hectare over a single flowering season at these two study sites at the planting densities expected of a pulpwood plantation. This represented 8 and 211 flowers per tree respectively. As tree density decreased, the production of flowers and capsules increased on both a per-tree and per-hectare basis. It is estimated that the number of flowers per hectare is likely to be anywhere between between 1.4 and 10-fold greater under the spacing expected in sawlog regimes (250 trees ha^?1). This difference in reproductive output between plantations of E. nitens that use different spacing regimes is one of the many factors that need to be considered in assessing the risk of wilding establishment or hybridisation with adjacent native eucalypts.     

Mortality of Eucalyptus marginata (jarrah) and E. calophylla (marri) trees following stem injection: effects of herbicide,dose, season,and spacing of injections

Mortalities of Eucalyptus marginata Donn ex Smith (jarrah) and E. calophylla R.Br, (marri) trees injected with Roundup^TM (360 g glyphosate l^?1 ) or Tordon Timber Control^TM (50 g picloram l^?1 and 100 g triclopyr l^?1 ) (P+T) were determined at doses of 5 to 80 grams of active ingredient (g.a.i.) m^?2 of stem basal area for glyphosate, and 2 to 40 g.a.i. m^?2 for P+T. The effect of spacing of injections around the tree bole was examined. Seasonal variation in mortality was examined in relation to atmospheric vapour pressure deficit (v.p.d.) and soil water deficits.

Glyphosate was more effective in killing E. marginata trees, whereas P+T tended to be more effective in killing E. calophylla trees. The optimum doses of glyphosate and P+T for E. marginata trees were 20 g.a.i. m^?2 and 15 g.a.i. m^?2 respectively, and for E. calophylla 80 g.a.i. m^?2 and 15 g.a.i. m^?2 respectively. Spacing of injections around the circumference of the tree did not have a significant effect on the mortality of E. marginata trees injected with glyphosate. However, mortality of E. calophylla trees injected with P+T declined from 89% at 10–15 cm spacing to 70% at 25–50 cm spacing.

There were strong seasonal effects with both herbicides and in both species, with mortality higher (70 - 90 % mortality) in seasons other than summer (30 - 50 % mortality). For E. marginata trees injected with glyphosate, mortality declined linearly with increasing v.p.d., from 95% at a v.p.d. of 0.5 kPa, to 25% at 4.5 kPa. For E. calophylla trees injected with P+T, mortality declined linearly with increasing v.p.d., from 85% mortality at a v.p.d. of 0.5 kPa, to 50% at 3.0 kPa. Stem injection of both species should only be carried out when the vapour pressure deficit on the day prior to stem injection is less than 1.5 kPa.     

身高、体重对青少年骨密度的影响

目的观察青少年时期(6～18岁)男女骨密度(BMD)和身高、体重的变化规律。方法利用双能X线骨密度仪对1008例健康男女学生行全身扫描,按性别不同,每1岁分一个组。结果6～14岁女孩和6～16岁男孩其身高、BMD和BMC年增长较快(P<0.05～0.001),其后男女孩的身高、BMD和BMC年增长就都不明显(P>0.05)。12岁以前女孩和14岁以前男孩其身高与BMD呈明显正相关(P<0.01～0.001,r=0.402～0.814),之后身高与BMD无相关性。6～18岁男女孩体重与BMD始终呈显著性正相关(P<0.001,r=0.654～0.864)。结论青少年男女身高、BMD和BMC生长发育的重要时期是:女孩在14岁以前,男孩在16岁以前。身高和体重对BMD都有影响,但以体重对BMD的影响更大。     

中药骨补方对骨质疏松症患者疼痛及骨密度的影响

目的研究中药骨补方对骨质疏松症患者的疼痛及骨密度的影响,从而为临床应用骨补方治疗骨质疏松症提供可靠依据。方法选择门诊120例,分为治疗和对照两组,每组60例,治疗组:中药骨补方+降钙素+钙剂;对照组:降钙素+钙剂:15d为1个疗程,治疗3个疗程后观察疼痛缓解情况及骨密度的改善情况及副作用。结果A组疼痛极点由治疗前的1.97降至1.06(P<0.01)。骨密度较治疗前有显著改善(P<0.01)。B组疼痛极点由治疗前的1.76降至1.64(P>0.05),骨密度较治疗前有改善(P<0.05),两组的疼痛缓解及骨密度改善有明显差别(P<0.05)。结论中药骨补方对骨质疏松症患者的疼痛缓解和骨密度的改善作用明显,无副作用。     

The effect of protein density of food on food intake and nutritional status of tumor-bearing rats

Current clinical practice emphasizes increasing calorie and protein intake to abate the nutritional decline that frequently occurs in cancer patients. Using an animal model of tumor-induced anorexia, we found that increasing the protein density of food resulted in a net increase in protein intake, but a decrease in the food intake of both healthy and tumor-bearing animals. The increased protein intake did not affect the nutritional status of tumor-bearing animals as indicated by body weight or serum levels of total protein, insulin, or insulin-like growth factor 1. These data suggest that factors regulating feeding responses to increased protein density of food are intact in hypophagic tumor-bearing rats, and that increased protein intake does not influence plasma levels of hormones requisite for protein synthesis. These data may partially explain why interventions to improve the nutritional intake of cancer patients have marginal effects on body weight, accrual of lean body mass, or synthesis of visceral proteins. © 1997 John Wiley & Sons, Inc. Res Nurs Health 20: 131–138, 1997     

耳针与补肾食疗对去势后骨质疏松症雌鼠骨密度和甲状腺功能变化的影响

目的：验证耳穴和补肾食疗防治骨质疏松症的疗效并探讨其治疗机理。方法：将切除6月龄雌鼠双侧卵巢建立骨质疏松症的动物模型,以假手术组和雌二醇组作为对照组。耳针组、补肾食疗组、耳针 补肾食疗组、雌二醇组分别经耳针、补肾补肾食疗和雌二醇的3个月治疗。用放免法测定大鼠血清的E2、T3、T4、TSH、PTH和骨密度、骨矿物含量。结果及结论：耳针、“补肾”食疗、雌二醇的治疗均能提高去势雌鼠的骨密度、骨矿物含量。其机理可能通过提高去势雌鼠的雌激素水平,调整垂体-甲状腺轴功能,从而抑制骨吸收,促进骨形成,降低骨转换率,纠正骨代谢的负平衡。     

脊髓损伤对大鼠股骨骨密度与生物力学特性的影响

目的探讨脊髓损伤(spinal cord injury, SCI)对大鼠股骨生物力学和骨密度(bone mineral density, BMD)的影响. 方法将40只3月龄大鼠随机分为SCI组和对照组,SCI组于T10椎体处完全切断脊髓,对照组仅行椎板切除术.于术后3,6周分2批处死动物进行股骨骨密度和生物力学测定. 结果术后3周时SCI组大鼠股骨远端BMD较对照组显著下降(P<0.05);术后6周时SCI组股骨近端BMD与对照组比较,下降差异显著(P<0.05);股骨远端BMD较对照组下降差异非常显著(P<0.01);股骨干BMD与对照组相比有降低趋势,但无统计学意义.术后3周时股骨颈最大载荷、最大变形、结构刚度及能量吸收在2组间差异均无统计学意义.术后6周时最大变形、结构刚度和能量吸收均低于对照组(P均<0.05),最大载荷低于对照组,差异具有极显著性意义(P<0.01). 结论脊髓损伤后松质骨骨密度和生物力学性能的降低先于密质骨.脊髓损伤后6周时SCI组股骨松质骨的骨密度及生物力学参数均显著低于对照组,脊髓损伤后6周的大鼠可作为骨质疏松动物模型.     

Addition of a short central extension to surface cemented tibial trays in primary TKA: an in vitro study of the effect on initial fixation stability and its relationship to supporting bone density

BACKGROUND: Short central extensions which do not enter the tibial medullary canal are incorporated to cemented tibial components to increase initial stability in primary total knee arthroplasty. Their role in tibiae of differing preoperative mechanical quality has been little studied. METHODS: Twelve embalmed cadaveric tibiae were paired and divided into two groups, receiving a similar cemented tibial component with or without a non-cemented short central extension (10 mm diameter, 35 mm length). The specimens were subjected to 6000 cycles of a medially applied 1350 N load. Relative bone-tray displacements were measured and the evolution of inducible and permanent micromotions were computed. The apparent density of the cancellous bone under the tibial tray and at the area to support the extension was computed from computed tomography images of each specimen. FINDINGS: No significant differences between groups were detected for any parameters. For the group with extension, a significant negative linear correlation (P = 0.009, r(2) = 0.849) was found between the inducible tilt of the tray and the bone density at the zone of the extension. Also a trend towards a negative linear relation (P = 0.07, r(2) = 0.59) was observed for the same group between maximum subsidence and apparent density at the zone of the extension. INTERPRETATION: The study did not find that the addition of a non-cemented short central extension provides any overall improvement of the initial fixation stability. However, it was found that short extensions may enhance tilting stiffness of the bone-implant construct if bone of sufficient mechanical quality is located around its supporting area.     

载脂蛋白E模拟肽ApoE23对细菌性脓毒血症小鼠血浆脂多糖浓度的影响及机制研究

目的 观察载脂蛋白E (ApoE)模拟肽ApoE23对细菌性脓毒血症小鼠血浆脂多糖(LPS)质量浓度变化的影响及其对肝脏低密度脂蛋白受体(LDLR)表达的调节作用.方法 设计ApoE模拟肽(ApoE23)并采用固相合成法进行合成,高效液相色谱(HPLC)技术对合成物进行纯化,电离子质谱对合成物进行鉴定并对合成物进行氨基酸组成分析;B组鼠伤寒沙门氏菌诱导C57BL细菌性脓毒血症模型并对感染小鼠尾静脉注射ApoE23进行治疗.小鼠血浆LPS质量浓度测定采用连续透射免疫比浊法.采用定量RT-PCR技术及Western blot技术检测小鼠肝脏中LDLRmRNA及蛋白质表达水平的变化.结果 细菌性脓毒血症小鼠血浆LPS浓度显著升高,肝脏LDLR表达明显降低.ApoE23治疗明显降低细菌性脓毒血症小鼠血浆LPS浓度,并使细菌感染导致的小鼠肝脏LDLR mRNA和蛋白质低表达得到明显纠正.结论 ApoE23可能是一种潜在的抗细菌性脓毒血症药物,其作用机制可能与其调解肝脏LDLR表达有关.     

合成磁共振成像不同带宽对T1、T2及PD测量值的影响—体膜研究

目的 观察多动态多回波序列(multi-dynamic multi-echo,MDME)不同带宽对T1、T2及质子密度(proton density,PD)测量值的影响.材料与方法 3种具有不同T1、T2及PD的体膜[脑灰质(gray matter,GM),白质(white matter,WM),脑脊液(cerebro...     

The effect of fasting on the interactions between human low density lipoproteins and calcium, heparin and chondroitin sulfate.

Fasting modified the in vitro interactions between low density lipoproteins (LDL) and glycosaminoglycans. Calcium had a potentiating effect on these interactions. LDL-calcium-heparin interaction was dependent on the presence of sialic acid whereas LDL-calcium-chondroitin sulfate interaction was inversely correlated with cholesterol content.