Mars: northern summer ice cap--water vapor observations from viking 2

Observations of the latitude dependence of water vapor made from the Viking 2 orbiter show peak abundances in the latitude band 70 degrees to 80 degrees north in the northern midsummer season (planetocentric longitude approximately 108 degrees ). Total column abundances in the polar regions require near-surface atmospheric temperatures in excess of 200 degrees K, and are incompatible with the survival of a frozen carbon dioxide cap at martian pressures. The remnant (or residual) north polar cap, and the outlying patches of ice at lower latitudes, are thus predominantly water ice, whose thickness can be estimated to be between 1 meter and 1 kilometer.     

Galactic water vapor emission: further observations of variability

Recent observations of the 1.35-centimeter line emission of water vapor from galactic sources show short-term variability in the spectra of several sources. Two additional sources, Cygnus 1 and NGC 6334N, have been observed, and the spectra of W49 and VY Canis Majoris were measured over a wider range of radial velocity.     

Viking: Mars atmospheric water vapor mapping experiment--preliminary report of results

Observations made from the Viking I orbiter show very little water vapor in the Mars atmosphere in the southern hemisphere (0 to 3 precipitable micrometers) with a gradual increase across the equator to northern latitudes. Maximum amounts between 20 and 30 micrometers have been observed in the short period covered by the observations to date. The season, northern midsummer, corresponds to the beginning of the water vapor cycle in that hemisphere. A strong repetitive diurnal cycling between the solid and vapor phases is observed at a site to the east of the Tharsis Ridge at 10 degrees north latitude; the vapor lies close to the martian surface and is most probably in saturation equilibrium with a surface haze or fog throughout much of the day.     

Clear air turbulence: detection by infrared observations of water vapor

"Forward-looking" infrared measurements of water vapor from the C-141A Kuiper Airborne Observatory of the National Aeronautics and Space Administration Ames Research Center show large, distinctly identifiable, signal anomalies from 4 to 10 minutes in advance of subsequent encounters with clear air turbulence (CAT). These anomalies are characteristically different from the signals not followed by CAT encounters. Results of airborne field trials in which the infrared radiometer was used indicate that, out of 51 situations, 80 percent were CAT alerts followed by CAT encounters, 12 percent were "false alarms" (CAT alerts not followed by CAT encounters), and 8 percent were CAT encounters not preceded by an infrared signal anomaly or CAT alert.     

夏玉米不同基因型水分适应性研究

对11个玉米杂交种在充分灌溉、节灌、干旱三种水分处理下的产量结果进行了分析,结果表明,不同杂交种的水分适应性不同,有些杂交种在各种水分条件下都有较好的适应性,这些杂交种的首要特性是具有较好的丰产性,并具有一定的抗旱性。     

谷氨酰胺对早期断奶山羊免疫功能影响的研究

通过颈静脉注射不同剂量的丙氨酰谷氨酰胺对山羊免疫功能的影响,选用出生日期和体重相近的12头波尔山羊,随机分为4组,(60±1)d一次性断奶。连续注射不同剂量的丙氨酰谷氨酰胺7 d。结果表明:补充不同剂量谷氨酰胺可有效地增加外周血CD4+和CD8+淋巴细胞的含量,使CD4+/CD8+比值增高,同时使血清IgA和IgG含量及十二直肠、空肠、回肠、盲肠和结肠黏液中S-IgA含量显著升高,从而使山羊机体的免疫能力增强。     

Ambient levels of ozone reduce net photosynthesis in tree and crop species

Experiments were conducted to measure the photosynthetic response of three crop and four tree species to realistic concentrations of ozone and (for tree species only) simulated acidic rain. The ozone concentrations were representative of those found in clean ambient air, in mildly to moderately polluted air such as occurs in much of the United States during the summer, and in more heavily polluted air. However, the highest concentrations of ozone used were lower than those found regularly in the Los Angeles area. The mean pH of the simulated acid rain treatments ranged from more alkaline to much more acidic than the mean pH of precipitation in the United States. Exposure to any increase in ozone reduced net photosynthesis in all species tested. In contrast, acidic rain had no negative effect on photosynthesis in tree species, and no interaction between ozone and acidic rain was observed. Ozone-induced reductions in photosynthesis were related to declines in growth or yield. Species with higher stomatal conductances and thus higher potential for pollutant uptake exhibited greater negative responses to similar ozone treatments. Since exposure to ozone concentrations typical of levels of the pollutant observed in the eastern half of the United States reduced the rates of net photosynthesis of all species tested, reductions in net photosynthesis may be occurring over much of the eastern United States.     

Evidence of water vapor in excess of saturation in the atmosphere of Mars

The vertical distribution of water vapor is key to the study of Mars' hydrological cycle. To date, it has been explored mainly through global climate models because of a lack of direct measurements. However, these models assume the absence of supersaturation in the atmosphere of Mars. Here, we report observations made using the SPICAM (Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) instrument onboard Mars Express that provide evidence of the frequent presence of water vapor in excess of saturation, by an amount far surpassing that encountered in Earth's atmosphere. This result contradicts the widespread assumption that atmospheric water on Mars cannot exist in a supersaturated state, directly affecting our long-term representation of water transport, accumulation, escape, and chemistry on a global scale.     

南疆夏播无籽西瓜栽培技术要点

2000年在南疆莎车和阿瓦提等县开始引种无籽西瓜,至2004年平均单产产值及纯收入均较传统的夏播玉米增一倍,从夏播无籽西瓜的播前准备、品种、播种期、种子处理、苗期管理、授粉留果、肥水管理、果实采收、病害防治等方面总结了夏播无籽西瓜的栽培技术要点。     

Environmental mercury: rapid determination in water at nanogram levels

Mercury compounds and free mercury are determined by emission spectrophotometry in a radiofrequency helium plasma. The method is simple, rapid, directly applicable to environmental water samples, and subject to few interferences. The useful working range is 10 nanograms to 10 micrograms, or 1 part per billion to 1 part per million in 10 milliliters of sample. The limit of detection is about 2 nanograms.     

Chemical loss of ozone in the arctic polar vortex in the winter of 1991-1992

In situ measurements of chlorine monoxide, bromine monoxide, and ozone are extrapolated globally, with the use of meteorological tracers, to infer the loss rates for ozone in the Arctic lower stratosphere during the Airborne Arctic Stratospheric Expedition II (AASE II) in the winter of 1991-1992. The analysis indicates removal of 15 to 20 percent of ambient ozone because of elevated concentrations of chlorine monoxide and bromine monoxide. Observations during AASE II define rates of removal of chlorine monoxide attributable to reaction with nitrogen dioxide (produced by photolysis of nitric acid) and to production of hydrochloric acid. Ozone loss ceased in March as concentrations of chlorine monoxide declined. Ozone losses could approach 50 percent if regeneration of nitrogen dioxide were inhibited by irreversible removal of nitrogen oxides (denitrification), as presently observed in the Antarctic, or without denitrification if inorganic chlorine concentrations were to double.     

农田冠层与大气水汽通量耦合分析

退耦因子 (Ω)是表征作物与周围大气水汽交换的重要指标。研究了引入Ω评价冬小麦与大气系统潜热通量的耦合度。一般在早晨和接近傍晚时作物与大气之间有较好的耦合度 ,主要是由于此时冠层导度 (gc)小 ;中午时由于风速很大 ,并且gc 达到全天最大值 ,作物与大气耦合度较差。Ω的季节变化由gc 控制 ,而gc受叶面积指数的影响。在拔节期以前有均衡潜热通量 (LEeq) >实际潜热通量 (LE) >强加潜热通量 (LEimp)的趋势 ,而在拔节期以后则呈强加潜热通量 (LEimp) >实际潜热通量 (LE) >均衡潜热通量 (LEeq)的变化趋势。     

The neural basis of loss aversion in decision-making under risk

People typically exhibit greater sensitivity to losses than to equivalent gains when making decisions. We investigated neural correlates of loss aversion while individuals decided whether to accept or reject gambles that offered a 50/50 chance of gaining or losing money. A broad set of areas (including midbrain dopaminergic regions and their targets) showed increasing activity as potential gains increased. Potential losses were represented by decreasing activity in several of these same gain-sensitive areas. Finally, individual differences in behavioral loss aversion were predicted by a measure of neural loss aversion in several regions, including the ventral striatum and prefrontal cortex.     

南方夏季高温条件下7种观赏草的光合动态及水分利用特性

通过测定7种引进观赏草光合特性的月动态及日动态变化,并观察其田间生长情况,探讨光合作用对夏季高温的响应机制和观赏草的水分利用特性.结果表明:净光合速率(Pn)、气孔导度(Cond)、蒸腾速率(Tr)及水分利用率(WUE)、内部水分利用效率(WUEi)均与观赏草的耐热性呈正相关,其中品种耐热性与Pn、Cond和Tr的相关性达到了显著水平(P<0.05),与WUE、WUEi的相关性不显著.金红羽狼尾草、矮蒲苇的Pn、Tr、Cond平均值较高,WUE也较高,为极耐热型观赏草;紫梦狼尾草、细叶画眉草、细叶芒及粉黛乱子草的Pn值相近,差异不显著,同为中等耐热性观赏草.花叶蒲苇的Pn、Tr、Cond各项指标偏低,生长量偏小,耐热性最差.     

Respiratory control: loss in mitochondria from diseased plants

Mitochondria from healthy oat seedlings oxidized succinate with good respiratory control and high ratios of adenosine diphosphate to oxygen. After treatment with victorin, the pathotoxin responsible for symptoms of Victoria blight of oats, susceptible seedlings yielded mitochondria with little respiratory control and lower ratios of adenosine diphosphate to oxygen. No such effects were obtained with victorin-treated resistant seedlings or when victorin was added directly to mitochondria from healthy susceptible or resistant plants. These data indicate that victorin-induced disease results in a reduction in efficiency of the energy-generating system of isolated mitochondria.     

Global cooling after the eruption of Mount Pinatubo: a test of climate feedback by water vapor

The sensitivity of Earth's climate to an external radiative forcing depends critically on the response of water vapor. We use the global cooling and drying of the atmosphere that was observed after the eruption of Mount Pinatubo to test model predictions of the climate feedback from water vapor. Here, we first highlight the success of the model in reproducing the observed drying after the volcanic eruption. Then, by comparing model simulations with and without water vapor feedback, we demonstrate the importance of the atmospheric drying in amplifying the temperature change and show that, without the strong positive feedback from water vapor, the model is unable to reproduce the observed cooling. These results provide quantitative evidence of the reliability of water vapor feedback in current climate models, which is crucial to their use for global warming projections.     

遮阳网覆盖对初夏湿栽水芹产量及品质的影响

在晚春采用单层遮阳网覆盖栽培湿栽水芹试验的基础上,进一步于初夏开展多层遮阳网覆盖栽培试验,比较了水芹产量、小叶总黄酮含量、叶柄粗纤维和总酚含量及DPPH自由基清除率等指标.结果表明,随覆盖层数增加,水芹产量显著下降,多项品质指标也有不同程度变化.     

臭氧水溶液治疗复发性口腔溃疡50例的临床疗效观察

目的 观察臭氧水溶液治疗复发性口腔溃疡的临床疗效.方法 100例复发性口腔溃疡患者随机分为实验组和对照组,每组50例.对照组采用常规治疗措施,实验组在对照组的基础上加用臭氧水溶液治疗,治疗4周并进行随访.治疗结束后检测患者创口的细菌检出率,同时记录并比较两组患者的临床疗效、止痛时间、溃疡愈合时间,以及治疗结束后3个月和6个月的复发例数.结果 实验组的临床疗效显著优于对照组,创口细菌检出率低于对照组,溃疡时间、溃疡数、止痛时间、愈合时间以及复发例数也比对照组少,差异均有统计学意义(P＜0.01).结论 臭氧水溶液治疗复发性口腔溃疡效果好,安全性高,值得推广.     

Transport and loss of nitrous oxide in soil water after forest clear-cutting

Whole-tree harvesting increased the concentration of nitrous oxide dissolved in soil water by two orders of magnitude over the concentration expected in equilibrium with the atmosphere. In contrast, the nitrous oxide content of soil water in an intact, second-growth forest was close to the expected theoretical value. Nitrous oxide, produced at active sites in the soil, dissolves in soil water and is transported to seeps and streams where it rapidly degasses from the solution and is released into the atmosphere. This loss of nitrous oxide after clear-cutting is not important to the nitrogen economy of the site; however, it may be important to the global atmospheric budget of nitrous oxide. Sources of nitrous oxide may have been overlooked because nitrous oxide emissions can be separated in time and space from the sites of the most intense production of nitrous oxide.     

日粮电解质平衡对开产笼养蛋鸭的影响

选用17周龄笼养金定蛋鸭108只,随机等分6组,研究玉米-豆粕日粮中不同电解质平衡值(DEB)对夏季笼养蛋鸭开产时间、生产性能、蛋品质及相关血液指标的影响。各组日粮电解质平衡值分别为50,150,200,250,300,350mmol·kg-1,试验期为6周。结果表明:①饲喂不同DEB值日粮的6组试鸭,其6周平均产蛋率分别为27.38%,31.48%,30.29%,36.24%,32.41%,28.97%;6周平均蛋重(g/枚)分别为47.89,48.23,48.52,52.56,50.25,52.00;②各组蛋鸭平均蛋重随DEB值的提高而提高(P<0.05),蛋壳厚度和蛋壳强度存在由低到高的趋势(P>0.05)。各处理组蛋鸭血液pH值、HCO3-浓度也随之有提高的趋势(P>0.05)。血清中[DEB=Na++K+-Cl-]随DEB值的提高而提高(P<0.05);③饲喂日粮DEB值为250mmol·kg-1与300mmol·kg-1的两试验组,至22周龄产蛋达到群体开产水平(产蛋率≈50%),达到适期开产。