Evidence for large upward trends of ultraviolet-B radiation linked to ozone depletion

Spectral measurements of ultraviolet-B radiation made at Toronto since 1989 indicate that the intensity of light at wavelengths near 300 nanometers has increased by 35 percent per year in winter and 7 percent per year in summer. The wavelength dependence of these trends indicates that the increase is caused by the downward trend in total ozone that was measured at Toronto during the same period. The trend at wavelengths between 320 and 325 nanometers is essentially zero.     

Ultraviolet spectroscopy of venus: initial results from the pioneer venus orbiter

Ultraviolet spectroscopy of the Venus cloud tops reveals absorption features attributed to sulfur dioxide in the atmosphere above the cloud tops. Measurements of scattered sunlight at 2663 angstroms show evidence for horizontal and vertical inhomogeneities in cloud structure. Images of the planet at SO(2) absorption wavelengths show albedo features similar to those seen at 3650 angstroms from Mariner 10. Airglowv emissions are consistent with an exospheric temperatuire of approximately 275 K, and a night airglows emission has been detected, indicating the precipitation of energy into the dark thermosphere.     

Opponent color cells in the cat lateral geniculate nucleus

A microelectrode survey of the cat lateral geniculate has uncovered an infrequent new type of lateral geniculate cell in layer B with "on" center responses to short wavelengths and "off" center responses to long wavelengths. The short wavelength responses are mediated by cones with peak sensitivity at about 450 nanometers, and the long wavelength responses by cones with peak sensitivity at 556 nanometers. Two of double opponent color cells also had double opponent features.     

Middle infrared thermal maps of venus at the time of the galileo encounter

Images of the disk of Venus, taken at wavelengths between 8 and 22 micrometers, were obtained a few days after the Galileo spacecraft's closest approach on 8 February 1990; these images show variations in the thickness of the main H(2)SO(4) cloud deck and the overlying temperature structure. Several features are qualitatively similar to those of earlier observations, such as a hot region at the south pole, surrounded by a cold ;;collar,' and brightening toward the lower latitudes, where low-contrast banding appears. The collar does have a northern counterpart that is warmer, however. Equatorial limb darkening is quantitatively similar to that of previous observations; fairly constant at wavelengths up to 20 micrometers, where limb darkening increases substantially. In contrast to what was found in previous observations, polar and equatorial limb darkening are nearly the same at most wavelengths. A longitudinal variation is observable that is consistent with a wavenumber-2 behavior and a brightness maximum near local midnight.     

Summary of historical data: interpretation of the pioneer and voyager cloud configurations in a time-dependent framework

Ground-based imaging of Jupiter at visible and infrared wavelengths has been used to build up a time sequence of cloud feature variations. The global cloud configuration seen by Voyager 1 appears markedly different than that seen by Pioneer 10 and 11. In the context of historical data, these two different cloud distributions are not unique but part of a continuous spectrum of global variations. The most recent global changes occurred in a pattern which has been a characteristic trend observed many times before.     

Robust fitting of fluorescence spectra for pre-symptomatic wheat leaf rust detection with Support Vector Machines

Early recognition of pathogen infection is of great relevance in precision plant protection. Pre-symptomatic disease detection is of particular interest. By use of a laserfluoroscope, UV-light induced fluorescence data were collected from healthy and with leaf rust inoculated wheat leaves of the susceptible cultivar Ritmo 2-4 days after inoculation under controlled conditions. In order to evaluate pathogen impact on fluorescence spectra 215 wavelengths in the range of 370-800 nm were recorded. The medians of fluorescence signatures suggest that inoculated leaves may be separated from healthy ones, but high-frequency oscillations and individual reactions of leaves indicate that separability is difficult to achieve. The misbalance between the high number of measured wavelengths and the low number of training examples induces a high overfitting risk. For a pre-symptomatic pathogen identification a small number of robust features was desired which comprise most of the information relevant for the given classification task. Instead of choosing only the most relevant wavelengths, the coefficients of polynomials fitting the spectra were used for classification. They specify the global curve characteristics. Piecewise fitting by polynomials of fourth order led to high classification accuracy. Support Vector Machines were used for classification. Cross validation demonstrated that the achieved classification accuracy reached 93%. This result could be attained on the second day after inoculation, before any visible symptoms appeared. The described method is of general interest for pre-symptomatic pathogen detection based on fluorescence spectra.     

人工合成氧化铁矿物对土壤光谱特性的影响

通过化学合成和去除技术与光谱测定技术,研究了人工合成氧化铁矿物对土壤的反射光谱特性的影响,结果表明,添加人工合成针铁矿后土壤的光谱反射曲线在350~600 nm和840~1100 nm波段有明显的吸收谷,含不同比例人工合成针铁矿的土壤光谱反射率之差的最大值出现在418 nm处,另外在932 nm处也有一个比较大的差值。添加人工合成水铁矿后土壤的光谱反射曲线在450~720 nm和860~1400 nm波段有明显的吸收谷,另外在1900 nm处也有较明显的差异,含不同比例人工合成水铁矿的土壤光谱反射率之差的最大值出现在551 nm处,另外在946 nm处和1900 nm处也有比较大的差值。添加人工合成赤铁矿后土壤的光谱反射曲线在450~720 nm和860~1400 nm波段有明显的吸收谷,含不同比例人工合成赤铁矿的土壤光谱反射率之差的最大值出现在517 nm处,另外在916 nm处也有比较大的差值。     

Photometry from voyager 2: initial results from the neptunian atmosphere, satellites, and rings

The Voyager photopolarimeter successfully accomplished its objectives for the Neptune encounter, performing measurements on the planet, several of its satellites, and its ring system. A photometric map of Neptune at 0.26 micrometer (microm) shows the planet to be bland, with no obvious contrast features. No polar haze was observed. At 0.75 microm, contrast features are observed, with the Great Dark Spot appearing as a low-albedo region and the bright companion as being substantially brighter than its surroundings, implying it to be at a higher altitude than the Great Dark Spot. Triton's linear phase coefficients of 0.011 magnitudes per degree at 0.26 microm and 0.013 magnitudes per degree at 0.75 microm are consistent with a solid-surface object possessing high reflectivity. Preliminary geometric albedos for Triton, Nereid, and 1989N2 were obtained at 0.26 and 0.75 microm. Triton's rotational phase curve shows evidence of two major compositional units on its surface. A single stellar occultation of the Neptune ring system elucidated an internal structure in 1989N1R, in the approximately 50-kilometer region of modest optical depth. 1989N2R may have been detected. The deficiency of material in the Neptune ring system, when compared to Uranus', may imply the lack of a "recent" moon-shattering event.     

Microwave Edge Diffraction by Features in Saturn's Rings: Observations with Voyager 1

Classical edge diffraction patterns are formed at centimeter wavelengths by several features of Saturn's rings. These patterns were discovered in 3.6-and 13-centimeter radio signals from Voyager 1 during occultation by the rings. The observed shapes are in agreement with theoretical patterns computed for screens of perfectly abrupt edges having large but finite opacity. Comparison with models in which the opacity at the edge tapers to zero from a finite value sets a new bound of less than about 200 meters on the microwave edge thickness. Certain features of the data suggest a smaller upper bound of about 130 meters on the edge thickness.     

Photolytic cleavage of sulfonamide bonds

It has been found that the sulfonamide bond is relatively susceptible to photolytic cleavage. The breakdown was effected either by irradiation with a source having a continuous emission above the wavelengths of 1800 angstroms or by another source emitting principally at 2537 angstroms. Less destruction of the amino acids was seen with the latter relative to the sulfonamide bond cleavage. The cleavage was not effected by irradiation at wavelengths greater than about 3000 angstroms. Side reactions were noted involving decarboxylation, demination, and destruction of certain susceptible amino acids such as tryptophan. In only one case was a product found that arose from cleavage of a carboxamide bond; glycyltyrosine gave glycine and tyrosine upon irradiation. A yield of 75 percent of the corresponding amino acid has been obtained by irradiation of tosylhistidine; yields of 75 to 100 percent have been obtained from sulfamic acid (NH(2)SO(3)H). A qualitative method for identifying sulfonylated amino acids is described.     

Radar interferometric observations of venus at 70-centimeter wavelength

A radar interferometer was used to map unambiguously the surface reflectivity of Venus in the polarized mode at a wavelength of 70 centimeters. The observed region extended from 260 degrees to 30 degrees in longitude and from -60 degrees to 50 degrees in latitude with a surface resolution of approximately 3 degrees by 3 degrees . The result agrees well in most respects with earlier maps made elsewhere at shorter wavelengths and, in addition, discloses a number of new "features."     

Evidence for the exposure of water ice on Titan's surface

The smoggy stratosphere of Saturn's largest moon, Titan, veils its surface from view, except at narrow wavelengths centered at 0.83, 0.94, 1.07, 1.28, 1.58, 2.0, 2.9, and 5.0 micrometers. We derived a spectrum of Titan's surface within these "windows" and detected features characteristic of water ice. Therefore, despite the hundreds of meters of organic liquids and solids hypothesized to exist on Titan's surface, its icy bedrock lies extensively exposed.     

High-resolution microwave images of saturn

An analysis of high-resolution microwave images of Saturn and Saturn's individual rings is presented. Radio interferometric observations of Saturn taken at the Very Large Array in New Mexico at wavelengths of 2 and 6 centimeters reveal interesting new features in both the atmosphere and rings. The resulting maps show an increase in brightness temperature of about 3 K from equator to pole at both wavelengths, while the 6-centimeter map shows a bright band at northern mid-latitudes. The data are consistent with a radiative transfer model of the atmosphere that constrains the well-mixed, fully saturated, NH(3) mixing ratio to be 1.2 x 10(-4) in a region just below the NH(3) clouds, while the observed bright band indicates a 25 percent relative decrease of NH(3) in northern mid-latitudes. Brightness temperatures for the classical rings are presented. Ring brightness shows a variation with azimuth and is linearly polarized at an average value of about 5 percent. The variations in ring polarization suggest that at least 20 percent of the ring brightness is the result of a single scattering process.     

Skylab radar altimeter: short-wavelength perturbations detected in ocean surface profiles

Short-wavelength anomalies in sea surface topography, caused by the gravitational effects of major ocean bottom topographic features, have been detected by the radar altimeter aboard Skylab. Some features, such as deep ocean trenches, seamounts, and escarpments, displace the ocean surface by as much as 15 meters over 100-kilometer wavelengths. This experiment demonstrates the potential of satellite altimetry for determining the ocean geoid and for mapping major features of the ocean bottom.     

The nature of the near-infrared features on the venus night side

Near-infrared images of the Venus night side show bright contrast features that move from east to west, in the direction of the cloud-top atmospheric superrotation. Recently acquired images of the Venus night side along with earlier spectroscopic observations allow identification of the mechanisms that produce these features, their level of formation, and the wind velocities at those levels. The features are detectable only at wavelengths near 1.74 and 2.3 micrometers, in narrow atmospheric windows between the CO(2) and H(2)O bands. The brightest features have brightness temperatures near 480 Kelvin, whereas the darkest features are more than 50 Kelvin cooler. Several factors suggest that this radiation is emitted by hot gases at altitudes below 35 kilometers in the Venus atmosphere. The feature contrasts are produced as this thermal radiation passes through a higher, cooler, atmospheric layer that has horizontal variations in transparency. The 6.5-day east-west rotation period of the features indicates that equatorial wind speeds are near 70 meters per second in this upper layer. Similar wind speeds have been measured by entry probes and balloons at altitudes between 50 and 55 kilometers in the middle cloud layer. The bright features indicate that there are partial clearings in this cloud deck. The presence of these clearings could decrease the efficiency of the atmospheric greenhouse that maintains the high surface temperatures on Venus.     

Feature identification and location experiment

The feature identification and location experiment (FILE) senses radiation from the earth in spectral bands centered at 0.65 and 0.85 micrometers and compares ratios of the reflected solar radiation in the two wavelengths to make real-time classification decisions about four primary features: water, vegetation, bare land, and a cloud-snow-ice class. The radiance ratio classification algorithm successfully made automatic data-selection decisions. The classification image obtained on the mission is providing information needed to evaluate the FILE algorithm and system performance.     

土壤有机质高光谱特征与波长变量优选方法

【目的】探究土壤有机质的高光谱特征及响应规律,优选土壤有机质的敏感波长,降低土壤有机质高光谱估测模型复杂度,提高模型稳健性,为利用高光谱技术对农田土壤肥力的定量监测提供理论支撑。【方法】采集江汉平原潮土土样130个,将其中40个样本作为训练集,测量其去有机质前、后的土壤有机质含量及光谱数据,计算差值及变化率,分析土壤有机质含量变化对光谱特征的影响,结合无信息变量消除(uninformative variables elimination,UVE)、竞争适应重加权采样(competitive adaptive reweighted sampling,CARS)变量优选方法确定土壤有机质敏感波长;采用45个建模集样本,基于偏最小二乘回归(partial Least Squares Regression,PLSR)和反向传播神经网络(back propagation neural network,BPNN)建立土壤有机质含量的估算模型;利用45个验证集样本检验敏感波长对同类土壤的适用性。【结果】通过有机质去除试验,供试土壤的平均光谱反射率在全波段均有所增加,在可见光波段变化率高于近红外波段;比较UVE、CARS、UVE-CARS、CARS-UVE这4种变量优选方法,得到最佳变量优选方法为UVE-CARS,该方法从2001个波长变量中优选得到84个变量作为土壤有机质的敏感波长,分布于561—721、1 920—2 280 nm波段覆盖范围;基于敏感波长的PLSR、BPNN模型性能均优于全波段模型,其中,基于敏感波长的BPNN模型的估测能力高于PLSR,模型验证集R~2、RMSE、RPD、MAE、MRE值分别为0.74、1.33 g·kg~(-1)、2.02、1.04 g·kg~(-1)、6.2%,可实现土壤有机质含量的有效估测。【结论】通过训练集获得的土壤有机质敏感波长,能够实现对该试验区同种土壤类型样本土壤有机质含量的有效估测;利用去有机质试验结合变量优选方法确定的敏感波长建模,不仅将输入波长压缩至全波段波长数目的 4.2%,而且提升了模型估测精度,降低了变量维度和模型复杂度,为快速准确评估农田土壤有机质含量提供了新途径。     

Hot Plasma and Energetic Particles in Neptune's Magnetosphere

The low-energy charged particle (LECP) instrument on Voyager 2 measured within the magnetosphere of Neptune energetic electrons (22 kiloelectron volts /=0.5 MeV per nucleon) energies, using an array of solid-state detectors in various configurations. The results obtained so far may be summarized as follows: (i) A variety of intensity, spectral, and anisotropy features suggest that the satellite Triton is important in controlling the outer regions of the Neptunian magnetosphere. These features include the absence of higher energy (>/=150 keV) ions or electrons outside 14.4 R(N) (where R(N) = radius of Neptune), a relative peak in the spectral index of low-energy electrons at Triton's radial distance, and a change of the proton spectrum from a power law with gamma >/= 3.8 outside, to a hot Maxwellian (kT [unknown] 55 keV) inside the satellite's orbit. (ii) Intensities decrease sharply at all energies near the time of closest approach, the decreases being most extended in time at the highest energies, reminiscent of a spacecraft's traversal of Earth's polar regions at low altitudes; simultaneously, several spikes of spectrally soft electrons and protons were seen (power input approximately 5 x 10(-4) ergs cm(-2) s(-1)) suggestive of auroral processes at Neptune. (iii) Composition measurements revealed the presence of H, H(2), and He(4), with relative abundances of 1300:1:0.1, suggesting a Neptunian ionospheric source for the trapped particle population. (iv) Plasma pressures at E >/= 28 keV are maximum at the magnetic equator with beta approximately 0.2, suggestive of a relatively empty magnetosphere, similar to that of Uranus. (v) A potential signature of satellite 1989N1 was seen, both inbound and outbound; other possible signatures of the moons and rings are evident in the data but cannot be positively identified in the absence of an accurate magnetic-field model close to the planet. Other results indude the absence of upstream ion increases or energetic neutrals [particle intensity (j) < 2.8 x 10(-3) cm(-2) s(-1) keV(-1) near 35 keV, at approximately 40 R(N)] implying an upper limit to the volume-averaged atomic H density at R 22 keV) input on Neptune is approximately 3 x 10(7) W, surprisingly small when compared to energy input into the atmosphere of Jupiter, Saturn, and Uranus.     

Metacontrast and saccadic suppression

A vertical slit of light illuminated during horizontal saccadic eye movements appeared as a horizontally extended smear when stimulation was terminated before the saccade ended. However, on trials for which duration of illumination of the slit was extended into the period after the saccade, the smear appeared shorter and dimmer, and a clear image of the slit was seen. With further increases in duration, no smears were seen at the highest luminance of the slit employed, although smears were more than 2 log units above threshold when flashes were brief. This saccadic suppression is discussed in terms of metacontrast, with the accumulated luminance in the period after the saccade primarily responsible for masking the effects of the stimulation received during the movement of the eye.     

某鸡场疑似禽脑脊髓炎发病情况和病理形态学观察

1989年6月,呼和浩特地区某鸡场的57d龄鸡发病。病鸡主要临床症状有步态不稳,虚弱疲软,共济失调,头颈震颤或偏于一侧,有时不能站立或完全瘫痪,主要病变为非化脓性脑脊髓炎;动物接种试验成功,也出现类似的症状和病变,故诊断为疑似禽脑脊髓炎。