杉木人工林蒸散规律的研究及乱流扩散法应用的探讨

 本文根据乱流扩散法原理,利用实验集水区连续6年实测数据,对杉木人工林蒸散规律进行了探讨。结果表明：杉木人工林年平均蒸散量875.45mm,占年降雨量的82.2%。其中,林冠蒸散量781.77mm,林地93.68mm,分别为总蒸散量的89.3%和10.7%。与水量平衡法的结果比较,为水量平衡法的101.2%。在研究蒸散规律的同时,对乱流扩散法的应用及参数的估算也进行了较详细的分析。     

Mutual information reveals variation in temperature-dependent sex determination in response to environmental fluctuation, lifespan and selection

Quantifying the degree to which sex determination depends on the environment can yield insight into the evolution, ecological dynamics, and functional aspects of sex determination. In temperature-dependent sex determination (TSD), theory often predicts a complete dependence of sex on temperature, with a switch-like reaction norm. However, empirical data suggest more shallow relationships between sex and temperature. Here, we demonstrate the usefulness of an index, mutual information (MI), to reflect the degree of temperature dependence in sex. MI depends on both the shape of a reaction norm and the natural temperature variation, thus providing a measure of TSD that is ecologically dependent. We demonstrate that increased lifespan and decreased environmental fluctuation predict reaction norms with high MI (switch-like). However, mutation and weaker selection on sex-specific performance reduce average MI in a population, suggesting that mutation-selection balance can resolve some of the conflict between theoretical predictions of individual-based optimality and population-based empirical results. The MI index allows clear comparison of TSD across life histories and habitats and reveals functional similarities between reaction norms that may appear different. The model provides testable predictions for TSD across populations, namely that MI should increase with lifespan and decrease with historical environmental fluctuations.     

Heat production and body temperature during cooling and rewarming in overweight and lean men

Objective: To compare overweight and lean subjects with respect to thermogenesis and physiological insulation in response to mild cold and rewarming. Research Methods and Procedures: Ten overweight men (mean BMI, 29.2 ± 2.8 kg/m²) and 10 lean men (mean BMI, 21.1 ± 2.0 kg/m²) were exposed to cold air for 1 hour, followed by 1 hour of rewarming. Body composition was determined by hydrodensitometry and deuterium dilution. Heat production and body temperatures were measured continuously by indirect calorimetry and thermistors, respectively. Muscle activity was recorded using electromyography. Results: In both groups, heat production increased significantly during cooling (lean, p = 0.004; overweight, p = 0.006). The increase was larger in the lean group compared with the overweight group (p = 0.04). During rewarming, heat production returned to baseline in the overweight group and stayed higher compared with baseline in the lean group (p = 0.003). The difference in heat production between rewarming and baseline was larger in the lean (p = 0.01) than in the overweight subjects. Weighted body temperature of both groups decreased during cold exposure (lean, p = 0.002; overweight, p < 0.001) and did not return to baseline during rewarming. Discussion: Overweight subjects showed a blunted mild cold‐induced thermogenesis. The insulative cold response was not different among the groups. The energy‐efficient response of the overweight subjects can have consequences for energy balance in the long term. The results support the concept of a dynamic heat regulation model instead of temperature regulation around a fixed set point.     

基于改进SPA法的耕地占补平衡生态安全评价

针对目前耕地占补平衡生态安全评价系统的不确定性,在理解集对分析(SPA)原理的基础上,利用原创联系度的可展性对其进行改进,将三级评判扩展到四级评判,并结合信息熵法,建立了基于改进SPA法的耕地占补平衡生态安全综合评价模型,并利用该模型对永川区影响耕地占补平衡生态安全的18项指标进行评价,得到永川区2005、2009、2015以及2020年的耕地占补平衡生态安全等级.此外,为了验证改进SPA法的可行性与合理性,将其评价结果与改进模糊综合评价结果以及多指标综合评价结果进行比较,研究结果表明:利用改进SPA法得到2005年永川区耕地占补平衡生态安全级别为Ⅱ级,2009年为Ⅲ级,2015年为Ⅳ级,2020年同样为Ⅳ级,整体上呈现出由Ⅱ级向Ⅳ级上升的趋势;改进SPA法综合评价结果与改进模糊综合评价结果以及多指标综合评价结果基本一致.研究认为利用集对势进行耕地占补平衡生态安全评价具有一定的可行性和可行性,评价结果比较贴近实际情况,为耕地占补平衡生态安全评价提供了一种科学合理且简单实用的评价方法.     

右美托咪定复合腰方肌阻滞对腹腔镜胃癌根治术患者术后镇痛效果、应激反应和Thl/Th2平衡的影响

摘要 目的：探讨右美托咪定复合腰方肌阻滞（QLB）对腹腔镜胃癌根治术患者术后镇痛效果、应激反应和Thl/Th2平衡的影响。方法：收集我院2019年1月~2021年5月接收的腹腔镜胃癌根治术患者80例。根据随机数字表法分为对照组和联合组,例数各为40例,对照组接受QLB,联合组接受右美托咪定复合QLB。对比两组视觉模拟评分法（VAS）评分。记录两组镇痛急救次数、镇痛泵有效按压次数。对比两组应激反应和Thl/Th2平衡。观察两组不良反应发生情况。结果：术后12 h、术后24 h、术后48 h联合组的VAS评分均低于对照组（P<0.05）。联合组的镇痛急救次数、镇痛泵有效按压次数少于对照组（P<0.05）。术后1 d,两组皮质醇（Cor）、肾上腺素（E）、促肾上腺皮质激素（ACTH）均较术前升高,但联合组低于对照组（P<0.05）。术后1 d,两组干扰素-γ（IFN-γ）、IFN-γ/白细胞介素-4（IL-4）较术前升高,且联合组高于对照组,IL-4较术前降低,且联合组低于对照组（P<0.05）。两组不良反应总发生率对比,无显著性差异（P>0.05）。结论：右美托咪定复合QLB可有效改善腹腔镜胃癌根治术患者术后疼痛情况,减轻应激反应,并改善术后免疫抑制状态,安全可靠。     

免疫平衡的重要调节者白细胞介素-21

白细胞介素-21（IL-21）是γc家族的一个新成员,主要由活化的CD4＋ T细胞产生,对多种表达IL-21受体（IL-21R）的细胞如T细胞、B细胞、NK细胞及DC细胞等均有作用。近年发现IL-21与Th细胞系中新发现的分支Th17细胞的发生密切相关,在调节CD4＋ T细胞究竟是分化为Th17细胞还是CD4＋CD25＋Foxp3＋ Treg细胞中有＂开关＂作用,从而对免疫系统发挥重要的调节作用,在自身免疫性疾病和抗肿瘤免疫中扮演着重要的角色。简要综述了IL-21与Th17细胞、CD4＋CD25＋Foxp3＋ Treg细胞之间的关系及对免疫平衡的调节作用。     

Successful amphiphiles as the key to crystallization of membrane proteins: Bridging theory and practice

Background

Membrane proteins constitute a major group of proteins and are of great significance as pharmaceutical targets, but underrepresented in the Protein Data Bank. Particular reasons are their low expression yields and the constant need for cautious and diligent handling in a sufficiently stable hydrophobic environment substituting for the native membrane. When it comes to protein crystallization, such an environment is often established by detergents.

Oxygen uptake does not increase linearly at high power outputs during incremental exercise test in humans

A group of 12 healthy non-smoking men [mean age 22.3 (SD 1.1) years], performed an incremental exercise test. The test started at 30 W, followed by increases in power output (P) of 30 W every 3 min, until exhaustion. Blood samples were taken from an antecubital vein for determination of plasma concentration lactate [La⁻]_pl and acid-base balance variables. Below the lactate threshold (LT) defined in this study as the highest P above which a sustained increase in [La⁻]_pl was observed (at least 0.5 mmol · l⁻¹ within 3 min), the pulmonary oxygen uptake (V˙O₂) measured breath-by-breath, showed a linear relationship with P. However, at P above LT [in this study 135 (SD 30) W] there was an additional accumulating increase in V˙O₂ above that expected from the increase in P alone. The magnitude of this effect was illustrated by the difference in the final P observed at maximal oxygen uptake (V˙O_2max) during the incremental exercise test (P _max,obs at V˙O_2max) and the expected power output at V˙O_2max(P _max,exp at V˙O_2max) predicted from the linear V˙O₂-P relationship derived from the data collected below LT. The P _max,obs at V˙O_2max amounting to 270 (SD 19) W was 65.1 (SD 35) W (19%) lower (P<0.01) than the P _max,exp at V˙O_{2max .} The mean value of V˙O_2max reached at P _max,obs amounted to 3555 (SD 226) ml · min⁻¹ which was 572 (SD 269) ml · min⁻¹ higher (P<0.01) than the V˙O₂ expected at this P, calculated from the linear relationship between V˙O₂ and P derived from the data collected below LT. This fall in locomotory efficiency expressed by the additional increase in V˙O₂, amounting to 572 (SD 269) ml O₂ · min⁻¹, was accompanied by a significant increase in [La⁻]_pl amounting to 7.04 (SD 2.2) mmol · l⁻¹, a significant increase in blood hydrogen ion concentration ([H⁺]_b) to 7.4 (SD 3) nmol · l⁻¹ and a significant fall in blood bicarbonate concentration to 5.78 (SD 1.7) mmol · l⁻¹, in relation to the values measured at the P of the LT. We also correlated the individual values of the additional V˙O₂ with the increases (Δ) in variables [La⁻]_pl and Δ[H⁺]_b. The Δ values for [La⁻]_pl and Δ[H⁺]_b were expressed as the differences between values reached at the P _max,obs at V˙O_2max and the values at LT. No significant correlations between the additional V˙O₂ and Δ[La⁻]_pl on [H⁺]_b were found. In conclusion, when performing an incremental exercise test, exceeding P corresponding to LT was accompanied by a significant additional increase in V˙O₂ above that expected from the linear relationship between V˙O₂ and P occurring at lower P. However, the magnitude of the additional increase in V˙O₂ did not correlate with the magnitude of the increases in [La⁻]_pl and [H⁺]_b reached in the final stages of the incremental test. Accepted: 30 October 1997     

北方稻田生态系统养分平衡研究

１９９４～１９９６年研究了５种不同模式水稻田生态系统养分平衡及养分效率．结果表明,不同模式的水稻田生态系统中,Ｎ输入输出基本相抵,处于平衡状态;Ｋ输入输出稍有盈余,唯Ｐ施用量较输出高１倍,使土壤中Ｐ有所积累．通过合理水肥调控措施,使水稻单产有所提高,肥料和养分利用率也得到不同程度的提高