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A novelty CL fiber which can expand L-band communication is proposed to meet the urgent demand of optical fiber transmission bandwidth for large capacity communication system. The influence of L-band attenuation on the OSNR (optical signal-to-noise ratio) of the system is analyzed and calculated; through the simulation of DWDM (dense wavelength division multiplexing) system, the requirements for FAWD (fiber attenuation warping degree) of CL fiber in 100Gbit/s rate DWDM system are obtained; and the influence of waveguide structure design on FAWD is tested. The results show that, the OSNR of L-band for will be 3 dB–3.5 dB worse than traditional C-band on 80 km span system; the FAWD@1625 nm (△α1625) and the FAWDD (fiber attenuation warping degree difference) of CL fiber are recommended to be controlled below 0.015 dB/km and 0.005 dB/km respectively to meet the link requirements in relevant standards. Additionally, it is feasible to improve the attenuation flatness of L-band by optimizing the waveguide structure design which is presented in the paper, that will provide a reference for the large-scale acquisition of novelty CL fibers in the future.

Abbreviation: HDM = house dust mite Indoor allergens such as house dust mite (HDM) are a contributing factor to the development of allergy and asthma in children. There is increasing [...]

Anthropogenic impacts and climate change modify instream flow, altering ecosystem services and impacting on aquatic ecosystems. Alpine rivers and streams on the Qinghai‐Tibet Plateau (QTP) are especially vulnerable to disturbance owing to limited taxonomic complexity. The effects of flow have been studied using specific taxa, yet the flow‐biota relationships of assemblages are poorly understood. A multi‐metric habitat suitability model (MM‐HSM) was developed using integrated measures of entire macroinvertebrate assemblages to substitute for habitat suitability indices derived from individual taxa. The MM‐HSM was trained using macroinvertebrates data from three alpine rivers on the QTP, including the Yarlung Tsangpo, the Nujiang, and the Bai rivers, and then validated using data from a forth alpine river (the Lanmucuo). The model produced predictions using the training data set (R2= 0.587) and the validation data set (R2= 0.489). By coupling the MM‐HSM with hydrodynamic simulations, the relationship between weighted usable area and flow (0.11–1.99 m3s−1) for macroinvertebrate assemblages was established, whereby a unimodal response pattern was observed for the Lanmucuo River. This contrast with monotonically positive or negative relationships observed for individual indicator taxa further supported our hypothesis that the response pattern of entire macroinvertebrate assemblages to flow would differ from responses of individual indicator taxa. The MM‐HSM provides a novel framework to quantify flow‐biota relationships, which is a useful approach for integrated river management. Anthropogenic impacts and climate change modify the flow of rivers. Aquatic ecosystems in alpine rivers, such as those on the Qinghai‐Tibet Plateau (QTP), are especially vulnerable to flow variations. Effects of flow on the fauna have been studied mostly in individual species, whereas the response of entire communities to flow is poorly understood. In this study, we collect macroinvertebrates and measure environmental conditions in four alpine rivers on the QTP. We propose an index to describe the integrated status of macroinvertebrate communities by using multivariate statistical and regression analyses, and couple this index with the hydrodynamic simulation to model how entire macroinvertebrate communities respond to flow in a representative alpine river. Our results show that macroinvertebrates respond first positively then negatively to flow, yielding a suitable flow condition for entire communities from integrated and holistic perspectives. We compare the response of entire macroinvertebrate communities to flow with responses of individual species, and detect very different patterns. These results provide a new perspective and strategy for future river management in pursuit of integrated ecosystem conservation. The multi‐metric habitat suitability model uses integrated measures of entire assemblages to substitute for indices of individual taxaThere is a unimodal relationship between macroinvertebrates and summer flow variations (0.11–1.99 m3s−1) in the Lanmucuo RiverThe response pattern of entire macroinvertebrate assemblages to flow differs dramatically from responses of individual taxa The multi‐metric habitat suitability model uses integrated measures of entire assemblages to substitute for indices of individual taxa There is a unimodal relationship between macroinvertebrates and summer flow variations (0.11–1.99 m3s−1) in the Lanmucuo River The response pattern of entire macroinvertebrate assemblages to flow differs dramatically from responses of individual taxa

In this article, procedure and efficiency of the reduced-basis approach in structural design computation are studied. As a model order reduction approach, it provides fast evaluation of a structural system in explicitly parameterized formulation. Theoretically, the original structural system is reduced to obtain a reduced system by being projected onto a lower dimensional subspace. However, in practice, it is a time-consuming process due to the iterations of adaptive procedure in subspace construction. To improve the efficiency of the method, some characteristics are analyzed. First, the accuracy of the subspace is evaluated and computational costs of procedures with different approaches are studied. Results show that the subspaces constructed by greedy adaptive procedures with different beginnings have the same accuracy. It is instructive that accuracy of the subspace is guaranteed by adaptive procedure. And the computational costs depend on the number of iterations in adaptive procedure. Thus, a modified adaptive procedure is proposed to reduce the computational costs and guarantee the accuracy. The modified adaptive procedure begins with experimental design methods to obtain a set of samples rather than a single sample and ends with the adaptive procedure. The start set of samples are selected by the following experimental design methods: 2kfactorial design, standard Latin design and Latin hypercube design. By being integrated with the experimental design, the modified adaptive procedure saves computational costs and retains the same accuracy as traditional procedure does. As an example, the outputs of a vehicle body front compartment subjected to a bending load are illustrated. It is proved that the proposed procedure is efficient and is applicable to many other structural design contexts.

As the reduced basis method is well used in some other fields to rapidly solve engineer systems, it is adapted to structural computation here. In this article, a reduced basis approach of computing structural linear elasticity problems is proposed to obtain rapid and reliable outputs using mixed interpolation of tensorial components elements. The procedure is as follows. First, structural computation problems based on finite element formulation should be parametrized. As an example, finite element formulation based on a type of element is analyzed and parameters in the formulation are extracted explicitly. Parametrized structural problem is built by assembling finite element formulation of components with parameters. Then, an approximate subspace of lower dimension based on structural outputs within whole parameter domain is constructed by an adaptive procedure. By projecting the parametrized structural problem onto that subspace, it is reduced to a parametrized lower dimension problem, which can be solved rapidly with random given parameters. The procedure is divided into two phases, naming offline and online procedure. Structures in vehicle design problems are employed to verify the feasibility of the procedure and deviation of the accuracy. The results showed that reduced basis approach of structural computation is applicable and efficient.

AbstractThe isothermal gas chromatographic behaviour of the group 5 elements Nb, Ta and Db was investigated in a brominating atmosphere using the OLGA technique. It was found that Db forms a very volatile compound, most likely the pentabromide, being more volatile than similar compounds formed under identical conditions with Nb and Ta, respectively. This observation is in disagreement with previous experimental investigations of the same compound but in agreement with theoretical prediction.

AbstractThe liquid-liquid extraction behavior of short-lived molybdenum and tungsten isotopes from HCl and HNO3as well as HF/HNO3acid media was studied using the α-benzoinoxime/chloroform system. The goal of the present experiments was to find an extraction system with a high selectivity for the group 6 elements in the periodic table which is suitable for the study the solution chemistry of seaborgium (Z=106). It was found that Mo and W are both effectively extracted using α-benzoinoxime as an extractant and the maximum extraction yield is 100% and 94% for Mo and W, respectively. Ions of MO22+(M=Mo, W) exist in HCl between the concentration range of 0.1−3 M and can be extracted quantitatively into the organic phase. The decrease of extraction yields at lower or higher acid concentration is due to the formation of anionic species MO42-or MO2Cl3-. The extraction behavior of Mo and W in HNO3solution is similar to that in HCl solution. In HNO3/HF mixed acid solutions, due to the formation of MO2F3-a decrease of extraction yield at higher HF concentration, similar to the case of HCl is observed. The extraction equilibrium is reached within 10−30 s, which means the extraction kinetics of α-benzoinoxime/chloroform extraction system is fast enough for the study of the isotope 265Sg. The extraction behavior of molybdenum and tungsten shows a distinct difference in the range of 0.05 to 0.2 M HF with 1 M HNO3. This shows that differences in the complexation with fluoride ion exist in Mo and W. This study focuses on the investigation of the tendency of group 6 element for complexation with fluoride ion.

Increased mucus production in asthma is an important cause of airflow obstruction during severe exacerbations. To better understand the changes in airway epithelium that lead to increased mucus production, ovalbumin-sensitized and -challenged mice were used. The phenotype of the epithelium was dramatically altered, resulting in increased numbers of mucous cells, predominantly in the proximal airways. However, the total numbers of epithelial cells per unit area of basement membrane did not change. A 75% decrease in Clara cells and a 25% decrease in ciliated cells were completely compensated for by an increase in mucous cells. Consequently, by day 22, 70% of the total epithelial cell population in the proximal airways was mucous cells. Electron microscopy illustrated that Clara cells were undergoing metaplasia to mucous cells. Conversely, epithelial proliferation, detected with 5-chloro-2-deoxyuridine immunohistochemistry, was most marked in the distal airways. Using ethidium homodimer cell labeling to evaluate necrosis and terminal dUTP nick-end labeling immunohistochemistry to evaluate apoptosis, this proliferation was accompanied by negligible cell death. In conclusion, epithelial cell death did not appear to be the stimulus driving epithelial proliferation and the increase in mucous cell numbers was primarily a result of Clara cell metaplasia.

A Monte-Carlo model of the MINISAT 01 satellite has been built. Thismodel, based on the GEANT software suite, is used to study the backgroundnoise induced in the cadmium zinc telluride (CZT) in the LEGRI detector.We find that the background noise count rate at the poles is ∼ 50%higher than at the equator. This increase is due to the effects of geomagneticrigidity cut-off. We also simulate the effects of passages through theSouth Atlantic Anomaly (SAA) with simulations showing an increase of∼ 0.5 counts cm-2sec-1after the SAA, in good agreement withobservational data.

The scope of observational astronomy in the gamma-ray region of the spectrum is vast. The intimate relationship of these energetic photons with their parent particles and fields provides a direct probe of the high-energy physics phenomena which take place throughout the Universe. As an added bonus the gamma-ray domain contains a wealth of diagnostic information within discrete emission lines, which are derived from a variety of processes including nuclear de-excitation, cyclotron emission, and matter-antimatter annihilation. Consequently observational gamma-ray astronomy addresses directly some of the most fundamental problems in both physics and astrophysics. However, low-energy gamma-rays are the most penetrating photons encountered in nature, and, whilst this factor provides a deep probe of cosmic objects, it ensures that gamma-ray telescopes are massive, both in terms of the stopping power required in the detector systems as well as their shields. Furthermore, the intimate relationship of gamma-rays with nuclear de-excitations ensures that the telescope itself becomes a bright source of background noise, a factor which is aggravated by the necessity that gamma-ray telescopes are obliged to operate in regions pervaded by intense particle fluxes. The background noise experienced in gamma-ray telescopes is, therefore, both high and extremely complex in its origin, and due to the high-energy content of individual photons, their numbers which arrive from distant cosmic sources are necessarily low, even for those objects which radiate the bulk of their power at gamma-ray wavelengths. Current gamma-ray telescopes are thus obliged to operate under conditions of intrinsically low signal-to-noise ratio and it is vital that techniques are developed which reduce the background noise level to more acceptable levels, thus improving the sensitivity. To achieve such a goal, a thorough understanding of the sources of background noise is first required before effective measures can be taken for its reduction.

The French soft ?-ray coded mask imaging telescope on board Soviet spacecraft GRANAT has experienced some unexpected gain drifts during its operation in the space. This gain instability seriously affected its data analysis and scientific interpretation of the results. After a detailed study of its background spectra and the long term performance of the detector, we have identified several background features which enable us to perform the in flight energy calibrations and gain corrections for the observations. The precision of such an energy calibration is estimated to be in the order of 0.5%, which is accurate enough for all types of data analysis such as spectrum de-convolution, and summation of observation spectra. More importantly it makes the search of astrophysical line features in the spectrum possible.

Three main imaging techniques used in low energy gamma-ray astronomy are briefly described. Their imaging capabilities are first compared from the point of view of image formation, then simulated images of the Galactic Centre are produced using these three techniques. The image qualities are evaluated with respect to their ability to determine the locations and intensities of point sources in the presence of background and diffuse emission.

Using grating shearing interferometry, a new and simple technique to measure the effective focal length of optical systems is described. The diffraction pattern of a phase grating positioned at the focal point of the lens under test is evaluated for this purpose. The relative lateral shift between the undiffracted zero order and the diffracted first orders caused by the grating is measured. By utilizing knowledge of the wavelength of light, the grating period, and the diameter of an aperture stop placed in front of the test lens, we can determine the effective focal length of the test lens. Results of measurements are presented and compared with calculated values. The dependence of the focal length on the wavelength of the light is shown by using two laser sources of different wavelengths. An analysis of the measurement accuracy is given.

Previously, Su et al. [Biotechnol Bioeng 42: 884-890 (1993)] reported improved production of rosmarinic acid by Anchusa officinalis in shake-flask cultures using a cultivation strategy that involved intermittent medium exchange. Implementation of this cultivation strategy in 2.5-l stirred-tank bioreactor cultures is investigated in the present study. Intermittent cell/medium separation in the bioreactor was accomplished by means of automated in situ culture filtration. In the bioreactor culture, rosmarinic acid production was found very sensitive to agitation and aeration conditions as well as dissolved oxygen concentration. A maximum cell density of 35g dry weight/l and a rosmarinic acid concentration of 3.7g/l were obtained by maintaining the dissolved oxygen concentration above 30% air saturation, gradually raising the impeller tip speed from 34cm/s to 72cm/s, and keeping the aeration rate at 0.44 vvm while increasing the O₂: air ratio in the gas feed stream to 4:1. This result is comparable with the data obtained from shake-flask cultures using the same culture strategy.

Surface pH of rat proximal jejunum as measured in vitro by pH-electrode was found to be significantly more acid than bulk bathing media of neutral pH. Below a bulk pH value between pH 4 and 5, surface pH was isohydric with bulk pH but with increasing alkalinity of the bulk pH, surface pH remained consistently more acidic. The maintenance of a low surface pH was sensitive to external medium glucose concentration, particularly between 2 and 10 mM concentration. A Lineweaver-Burk plot of the glucose-dependent decrement in surface pH demonstrated an apparentKmof 2 mM. Anoxia caused a significant elevation in the measured surface pH at 10 mM glucose concentration. Surface pH was found to be sensitive to buffer sodium ion concentration in the jejunum, an effect which was less marked in the distal ileum.

The analysis of compact astronomical objects has generally dealt with the physical properties of the source within a two-parameter space, which is defined by the spectral characteristics and time variability. This approach often leads to the situation whereby two or more very different models can explain the observations successfully. Polarimetric observations have the diagnostic potential to discriminate between the different compact source models and can offer a unique insight into the geometrical nature of the emission zones. To date, however, no polarization observation in the gamma-ray energy domain has been successfully performed, due to the difficulties in making polarimetric measurements in this high-energy region of the spectrum. In this paper the polarized gamma-ray emission mechanisms are reviewed with the emphasis on their detectable characteristics. Potential astronomical sites in which these emission mechanisms may be at work are discussed. Observational results obtained in other wavebands and theoretical predications made for some of the most likely astronomical sources of polarization are reviewed. Compton polarimetry has long been used in the field of nuclear gamma-ray spectroscopy in the laboratory. The operational principle behind all generations of nuclear gamma-ray polarimeters has been to measure the asymmetry in the azimuthal distribution of the scattered photons. However none of the polarimeters designed for laboratory experiments will be sensitive enough to observe even the strongest astronomical source. In the past few years there have been a number of innovative developments aimed at the construction of astronomical gamma-ray polarimeters, either as dedicated experiments or in missions with polarimetric capability. The designs of all the polarimeters are based on either discrete or continuous position sensitive detector planes. In this paper the data analysis techniques associated with this type of polarimeter are discussed as well as methods of removing some of the systematic effects introduced by a non-ideal detector response function and observation conditions. Laboratory tests of these new polarimetric techniques are reviewed. They demonstrate the feasibility of building a suitably sensitive astronomical gamma-ray polarimeter. Optimization of the design of pixellated detector array based polarimeters is also addressed. The INTEGRAL mission, which is to be launched by ESA in the year 2001, is the most likely telescope to perform the first successful gamma-ray polarization observation. The polarimetric characteristics of the two main instruments on board INTEGRAL are evaluated and their sensitivities to a wide range of potentially polarized gamma-ray sources are estimated.

A simple method for measuring both the numerical aperture and the f number of a lens system by means of a phase grating is described.

The article presents news briefs from Texas including the rescue of a woman from a tree after she got stuck, by the firefighters in Victoria; kicker K-Lani Nava to play in a Texas high school football state championship game; and completion of a trial for arm replant by the Army Medical Center.

Reports the smart sprayer developed by the University of Illinois at Urbana-Champaign (UIUC) to control weeds in Illinois. Specification of the sprayer; Sponsorship of Illinois Council on Food and Agricultural Research in the system; Objectives of the sprayer.

Hyperspectral remote sensing produces large volumes of data, quite often requiring hundreds of megabytes to gigabytes of memory storage for a small geographical area for one-time data collection. Although the high spectral resolution of hyperspectral data is quite useful for capturing and discriminating subtle differences in geospatial characteristics of the target, it contains redundant information at the band level. The objective of this study was to identify those bands that contain the most information needed for characterizing a specific geospatial feature with minimal redundancy. Band selection is performed with both unsupervised and supervised approaches. Five methods (three unsupervised and two supervised) are proposed and compared to identify hyperspectral image bands to characterize soil electrical conductivity and canopy coverage in agricultural fields. The unsupervised approach includes information entropy measure and first and second derivatives along the spectral axis. The supervised approach selects hyperspectral bands based on supplemental ground truth data using principal component analysis (PCA) and artificial neural network (ANN) based models. Each hyperspectral image band was ranked using all five methods. Twenty best bands were selected by each method with the focus on soil and plant canopy characterization in precision agriculture. The results showed that each of these methods may be appropriate for different applications. The entropy measure and PCA were quite useful for selecting bands with the most information content, while derivative methods could be used for identifying absorption features. ANN measure was the most useful in selecting bands specific to a target characteristic with minimum information redundancy. The results also indicated that a combination of wavebands with different bandwidths will allow use of fewer than 20 bands used in this study to represent the information contained in the top 20 bands, thus reducing image dat... [ABSTRACT FROM AUTHOR]

We present here a set of tools for space applications based on the Geant4 simulation toolkit, developed for radiation shielding analysis as part of the European Space Agency (ESA) activities in the Geant4 collaboration. The Sector Shielding Analysis Tool (SSAT) and the Materials and Geometry Association (MGA) utility will first be described. An overview of the main features of the MUlti-LAyered Shielding SImulation Software tool (MULASSIS) will follow. The tool is specifically addressed to shielding optimization and effects analysis. A Java interface allows the use of MULASSIS by the space community over the World Wide Web, integrated in the widely used SPENVIS package. The analysis of the particle transport output provides automatically radiation fluence, ionising and NIEL dose and effects analysis. ESA is currently funding the porting of this tools to a lowcost parallel processor facility using the GRID technology under the ESA SpaceGRID initiative. Other Geant4 present and future projects will be presented related to the study of space environment effects on spacecrafts. [Copyright &y& Elsevier]