Orientation by pigeons: is the sun necessary?

Although most recent hypotheses of pigeon homing have assigned an essential role to the sun, there has been some evidence suggesting that the sun is not essential. Two series of releases were designed to examine the question more carefully. Birds whose internal clocks had been shifted 6 hours were used in the critical tests. Under sun, the vanishing bearings of the clock-shifted birds were deflected in the direction predicted by a hypothesis of use of the sun as a simple compass. By contrast, under total overcast the bearings of both the clock-shifted and the control birds were homeward oriented and there was no difference between them, even at a release site the birds could never have seen previously. Therefore it is concluded that the sun is used as a compass when it is available, but that the pigeon navigation system contains sufficient redundancy to make accurate orientation possible in the absence of both the sun and familiar landmarks; the orientational cues used under such conditions do not require time compensation. This conclusion is in complete disagreement with the Matthews sun-arc hypothesis of pigeon navigation, and it makes necessary a major reformulation (at the very least) of the other principal hypothesis, that of Kramer.     

Pioneer 6: Measurement of Transient Faraday Rotation Phenomena Observed during Solar Occultation

Pioneer 6, which was launched into orbit around the sun on 16 December 1965, was occulted by the sun in the last half of November 1968. During the period in which the spacecraft was occulted by the solar corona, the S-band telemetry carrier underwent Faraday rotation as a result of this anisotropic plasma. The NASA-Jet Propulsion Laboratory 210-foot (64-meter) antenna of the Deep Space Network at Barstow, California, which was equipped with an automatic polarization tracking system, was used to measure this effect. Three large-scale transient phenomena were observed. The measurement of these phenomena indicated that Faraday rotation on the order of 40 degrees occurred. The duration of each phenomenon was approximately 2 hours. These phenomena appear to be correlated with observations of solar radio bursts with wavelengths in the dekametric region.     

云南生态环境与云南烤烟香气品质关系的探讨

 笔者分析了云南烤烟在质体色素类香气物质、叶面分泌物、酚类物质等烤烟中的重要香气物质与生态环境的关系,结果表明云南烤烟所处的高原生态条件,如海拔、光照等有利于其香气物质的形成,是云南烤烟香气风格形成的重要基础。     

不同干燥方法对无核白鸡心葡萄干色泽及次生代谢物质变化的影响

【目的】研究不同干燥工艺对葡萄干颜色及次生代谢物质的影响,为传统干燥工艺的改进提供理论依据。【方法】运用晒干和晾干两种制干方式,测定含水量、色差值、水分活度、总酚含量、总黄酮,分析颜色、酚类、酮类及香气物质。【结果】晒干方式干燥速率显著晾干方式,晾干方式葡萄果实内水分活度变化晒干方式,有利于形成绿色葡萄干;晒干、晾干方式葡萄干中总黄酮、多酚类物质含量先下降后上升的趋势,晾干葡萄干总黄酮、多酚类物质高于晒干葡萄干。制干过程中香气种类含量均呈现先上升后下降的趋势。【结论】采用晾干方式制干,干燥速率、水分活度变化均低于晒干方式,能较好的保存葡萄果实内的香气成分、总黄酮和多酚物质。     

晒青茶叶和烘青茶叶成分比较研究*

  对不同级别的晒青茶和烘青茶茶叶主要成分进行了测定,探讨了加工方式、茶叶等级与茶叶成分之间的关系。结果发现烘青茶和晒青茶水浸出物、茶多酚、咖啡碱含量都随着茶叶等级的降低而降低,水浸出物、茶多酚、咖啡碱含量与茶叶等级呈正相关;烘青茶和晒青茶灰分、茶多糖、茶褐素含量随等级的降低而升高,随着茶叶等级的降低茶叶中所含的粗老茶叶增加,灰分、茶多糖、茶褐素含量与茶叶等级呈负相关;同一等级烘青茶的水分、灰分含量小于同一等级晒青茶,而同一等级烘青茶的干物质和水浸出物的含量则高于同一等级晒青茶。     

3年生苦楝生长量与坡向、坡位关系的研究

采用随机区组调查法对寿宁县3年生苦楝与不同坡向、坡位的生长量关系进行研究,通过对比分析,结果表明：不同坡向、与坡位的生长量存在极显著差异,阳坡能显著促进苦楝生长,苦楝造林最好选择阳坡下部山地、农地。     

猪毛蒿不同炮制方法炮制前后化学成分变化

[目的]研究猪毛蒿不同炮制方法炮制前后水提取物、醇提取物含量、挥发性成分以及绿原酸含量差异,为寻找猪毛蒿炮制方法奠定基础.[方法]以重量法测定水提取物、醇提取物含量,GC-MS/MS测定挥发性成分,HPLC-UV测定绿原酸含量.[结果]与生品相比,晒干品的水、醇提取物含量均显著下降;烘干品水提取物含量下降,而醇提取物含量提高;阴干品无显著差异.GC-MS/MS分析不同炮制品中挥发性成分,从生品、阴干、晒干、烘干品中分别检出25、21、27、24个色谱峰,共有的组分有13个,且猪毛蒿炮制前后既有含量的改变,也有不同结构的成分出现,晒干与生品差距最大;HPLC-UV方法测定了绿原酸含量,发现炮制后均显著下降,含量从大到小依次为生品、阴干、晒干、烘干.[结论]猪毛蒿在加工过程中应尽量采用阴干方法,以防止有效成分损失.     

Spectra of backscattered light from the sea obtained from aircraft as a measure of chlorophyll concentration

Spectra of sun and skylight backscattered from the sea were obtained from a low-flying aircraft and were compared with measurements of chlorophyll concentration made from shipboard at the same localities and at nearly the same times. Increasing amounts of chlorophyll were found to be associated with a relative decrease in the blue portion of the spectra and an increase in the green. Anomalies in the spectra show that factors other than chlorophyll also affect the water color in some instances; these factors include other biochromes, suspended sediment, surface reflection, polarization, and air light.     

晒烟新品种丰产性与稳定性的研究

利用晒烟新品种在区域试验的资料，采用Ebarhart和Russell回归法析其产值及其构成因子（产量、均价）的稳定性，为新品种的合理利用与推广提供可靠依据。     

No evidence of a circumsolar dust ring from infrared observations of the 1991 solar eclipse

During the past 25 years there have been many attempts to detect a possible dust ring around the sun, with contradictory results. Before the 1991 eclipse, infrared eclipse experiments used single-element detectors to scan the corona along the ecliptic for excess surface brightness peaks. The availability of relatively large-format infrared array detectors now provides a considerable observational advantage: two-dimensional mapping of the brightness and polarization of the corona with high photometric precision. The 1991 eclipse path included the high-altitude Mauna Kea Observatory, a further advantage to measure the corona out to large angular distances from the sun. Results are reported from an experiment conducted on Mauna Kea with a HgCdTe-array detector sensitive to wavelengths between 1 and 2.5 micrometers, using broad-band J, H, and K filters. Although the sky conditions were not ideal, the H- and K-band surface brightnesses clearly show the inhomogeneous structure in the K-corona and the elliptical flattening of the F-corona, but no evidence of a circumsolar, local dust component out to 15 solar radii.     

Pairing and phase separation in a polarized Fermi gas

We report the observation of pairing in a gas of atomic fermions with unequal numbers of two components. Beyond a critical polarization, the gas separates into a phase that is consistent with a superfluid paired core surrounded by a shell of normal unpaired fermions. The critical polarization diminishes with decreasing attractive interaction. For near-zero polarization, we measured the parameter beta = -0.54 +/- 0.05, describing the universal energy of a strongly interacting paired Fermi gas, and found good agreement with recent theory. These results are relevant to predictions of exotic new phases of quark matter and of strongly magnetized superconductors.     

Epitaxial BiFeO3 multiferroic thin film heterostructures

Enhancement of polarization and related properties in heteroepitaxially constrained thin films of the ferroelectromagnet, BiFeO3, is reported. Structure analysis indicates that the crystal structure of film is monoclinic in contrast to bulk, which is rhombohedral. The films display a room-temperature spontaneous polarization (50 to 60 microcoulombs per square centimeter) almost an order of magnitude higher than that of the bulk (6.1 microcoulombs per square centimeter). The observed enhancement is corroborated by first-principles calculations and found to originate from a high sensitivity of the polarization to small changes in lattice parameters. The films also exhibit enhanced thickness-dependent magnetism compared with the bulk. These enhanced and combined functional responses in thin film form present an opportunity to create and implement thin film devices that actively couple the magnetic and ferroelectric order parameters.     

越冬返青期间小叶黄杨叶色与叶绿素荧光动力学变化

利用英国皇家园艺学会比色卡(RHSCC)与调制式叶绿素荧光分析技术,研究了由国外引种北京10余年的3个小叶黄杨品种‘绿美’、‘阳光’及‘冬绿’的越冬及返青过程中叶色时空变化规律以及叶绿素荧光动力学曲线及参数。结果表明:3个品种阳生叶的叶色在整个过程中均有不同程度的变化,其中‘绿美’变化最小,‘阳光’和‘冬绿’均发生严重变色现象,而其阴生叶叶色几乎没有变化;越冬及返青期间,3个品种不同生态型叶的叶绿素荧光动力学诱导曲线(FI)及后稳态叶绿素荧光多阶段曲线(SMS)动力学变化均有明显差异,且该差异具有品种特征;返青前阳生叶FI动力学活性及SMS波动幅度均明显低于同期的阴生叶,返青期间前者恢复速度也明显低于后者;冬季‘绿美’阳生叶能保持一定的光暗反应活性和电子传递速率,而‘阳光’和‘冬绿’则几乎停止活动。      

Polarized gamma-ray emission from the galactic black hole Cygnus X-1

Because of their inherently high flux allowing the detection of clear signals, black hole x-ray binaries are interesting candidates for polarization studies, even if no polarization signals have been observed from them before. Such measurements would provide further detailed insight into these sources' emission mechanisms. We measured the polarization of the gamma-ray emission from the black hole binary system Cygnus X-1 with the International Gamma-Ray Astrophysics Laboratory Imager on Board the Integral Satellite (INTEGRAL/IBIS) telescope. Spectral modeling of the data reveals two emission mechanisms: The 250- to 400-keV (kilo-electron volt) data are consistent with emission dominated by Compton scattering on thermal electrons and are weakly polarized. The second spectral component seen in the 400-keV to 2-MeV band is by contrast strongly polarized, revealing that the MeV emission is probably related to the jet first detected in the radio band.     

The thermal stability of water ice at the poles of mercury

Recent radar observations of Mercury have revealed the presence of anomalous radar reflectivity and polarization features near its north and south poles. Thermal model calculations show that, despite Mercury's proximity to the sun, the temperatures of flat, low-reflectivity surfaces at Mercury's poles are not expected to exceed 167 kelvin. The locations of the anomalous polar radar features appear to be correlated with the locations of large, high-latitude impact craters. Maximum surface temperatures in the permanently shadowed regions of these craters are expected to be significantly colder, as low as 60 kelvin in the largest craters. These results are consistent with the presence of water ice, because at temperatures lower than 112 kelvin, water ice should be stable to evaporation over time scales of billions of years.     

The Seismic Structure of the Sun

Global Oscillation Network Group data reveal that the internal structure of the sun can be well represented by a calibrated standard model. However, immediately beneath the convection zone and at the edge of the energy-generating core, the sound-speed variation is somewhat smoother in the sun than it is in the model. This could be a consequence of chemical inhomogeneity that is too severe in the model, perhaps owing to inaccurate modeling of gravitational settling or to neglected macroscopic motion that may be present in the sun. Accurate knowledge of the sun's structure enables inferences to be made about the physics that controls the sun; for example, through the opacity, the equation of state, or wave motion. Those inferences can then be used elsewhere in astrophysics.     

Spectrum and Distance of Source Sco XR-1

In a broad sky survey for x-ray sources in the 44-to 60-A range only Sco XR-1 was detected. The spectral evidence indicates that Sco XR-1 may lie within a few hundred light-years of the sun. Its spectrum appears to be complex possibly a mixture of thermal sources at different temperatures or of thermal and nonthermal components, as has been predicted for an active neutron star with an associated corona or magnetosphere.     

Cochlear distortion: effect of direct-current polarization

Intermodulation components (combination tones) appearing in microphonic potentials were measured from guinea pig cochleas with and without polarizing direct currents passing through the cochlear partition. At moderate intensities of stimulus the polarization had a qualitatively different effect on the distortion components than on their eliciting primaries or on pure tones simulating the distortion products. At high intensities, the primaries and the combination tones were similarly influenced by the polarizing current. It is concluded that cochlear distortion is a two-stage process, mechano-electrical at low levels and mechano-hydraulic at high levels.     

遮阴对大头茶、薄果猴欢喜幼苗生长的影响

对２ａ生大头茶（Ｇｏｒｄｏｎｉａａｃｕｍｅｎａｔａ）和薄果猴欢喜（Ｓｌｏａｎｅａｌｅｐｔｏｃａｒｐａ）幼苗进行遮阴实验，结果表明，大头茶幼苗的叶面积、茎长、枝长年变化曲线和总生量为：全光照＞部分光照＞部分阴暗＞阴暗；而薄果猴欢喜为：部分阴暗＞阴暗＞部分光照或全光照，这体现了阳性树种（大头茶幼苗）和阴性树种（薄果猴欢喜幼苗）的不同特点。从全光照到阴暗，大头茶、薄果猴欢喜幼苗的平均叶面积重（ＳＬＷ）和根／冠比均下降，而叶面积率（ＬＡＲ）均增加，并且，平均叶面积在部分阴暗下最高，全光照下最低。可见，大头茶、薄果猴欢喜幼苗对其相应光环境具有一定的适应能力     

阴生植物和阳生植物气孔数量比较分析

制作阳生植物（变叶木、香樟、鸳鸯茉莉）和阴生植物（巴西铁、富贵竹、竹芋）的上下表皮临时切片,采用光学显微镜观察并进行方差分析比较。结果发现：同种阴生植物或阳生植物下表皮气孔数量极显著多于上表皮;阳生植物上表皮气孔极少或无,而阴生植物上表皮有较多气孔。