Comparison of two scanning electron microscope techniques for examining daily growth increments on fish otoliths

With a secondary detector and a backscatter detector, total primary increment counts on the same otoliths were similar, but more samples could be counted using the backscatter detector and the percentage of unreadable area was consistently lower with this technique.     

Sensitivity of the IQM and MatriXX detectors in megavolt photon beams

AimThis study focused on evaluating the sensitivity of integral quality monitoring (IQM^®) system and MatriXX detectors. These two detectors are recommended for radiotherapy pre-treatment quality assurance (QA).BackgroundIQM is a large wedged-shaped ionisation chamber mounted to the linear accelerator (linac) head in practice. MatriXX consists of an array of ionisation chambers also attached to the linac head.Materials and methodsIn this study, the dosimetric performance and sensitivity of MatriXX and IQM detectors were evaluated using the following characteristics: reproducibility, linearity, error detection capability and three-dimensional conformal radiotherapy (3D-CRT) plans of the head and neck, thorax and pelvic regions.ResultsThis study indicates that the signal responses of the large ionisation chamber device (IQM) and the small pixel array of ionisation chambers device (MatriXX) are reproducible, linear and sensitive to MLC positional errors, backup jaw positional errors and dose errors. The local percentage differences for dose errors of 1%, 2%, and 3% were, respectively, within 0.35–8.23%, 0.78–16.21%, and 1.10–24.41% for the IQM device. While for the MatriXX detector, the ranges were between 0.24–3.19, 0.57–6.43 and 0.81–12.95, respectively. Since IQM is essentially a double wedge-shaped large ionisation chamber, its reproducibility and detection capability are competitive to that of MatriXX. In addition, the sensitivity of the two QA systems increases with an increase in escalation percentage, and the signal responses are patient plan specific.ConclusionsThe two detectors response signals have good correlations and they are accurate for pre-treatment QA. Statistically, (P < 0.05) there is a significant difference between the IQM and MatriXX response to dose errors.     

Comparative evaluation of photoionization and flame ionization detectors for ethylene analysis

Abstract. This paper compares the use of photoionization and flame ionization detectors (PID and FID. respectively) for the analysis of ethylene in plant physiological studies. It is shown that PID has the capability to analyse ethylene levels in the order of 1 mm³ m⁻³. This represents an increase in sensitivity over FID of several-fold. Evidence is presented that this enhanced sensitivity allows for measurement of the rate of ethylene production from plants in continuous-flow systems by taking air samples directly from the air stream, thus eliminating the need for selective collection and concentration of ethylene.     

Effect of light quality on movement of Pterostichus melanarius (Coleoptera: Carabidae)

Abstract Behaviour of nocturnal insects is routinely observed under red light, but it is unclear how the behaviour under red light compares to behaviour in complete darkness, or under a source of white light. Here, we measure movement behaviour of the nocturnal carabid beetle Pterostichus melanarius Illiger (Coleoptera: Carabidae) using camera recording under a near‐infrared (nir), red or white radiation source. Red light significantly reduced movement speed in females similar to the effect of white light and different from nir. Also movement activity and pause length were affected by radiation source, with a significant difference between nir and white light, and with intermediate values in red light. The results presented here indicate that P. melanarius has different movement behaviour under the three radiation sources and suggest that nir rather than red radiation is most appropriate for measuring behaviour in total darkness. However, in the field total darkness is rare both because of natural light sources such as the moon and stars but increasingly also because of ecological light pollution, and therefore red light may still be of use for observing ecologically and practically relevant natural night‐time behaviour.     

Actomyosin and movement in the angiosperm pollen tube: an interpretation of some recent results

Summary Recent confirmations of the presence of myosin in angiosperm pollen tubes indicate that an energy-transducing actomyosin system is involved in the motility system of the vegetative cells. Myosin has been localised by immunofluorescence on the surfaces of vegetative nuclei and generative cells. It has been shown to be associated with individual amyloplasts in grass pollen, and there are indications that it is present on other particulate bodies in the cytoplasm. The organelles in the leading part of the tube move along separate traffic lanes of acropetal and basipetal polarity, known from electron microscopy and phalloidin labelling to contain numbers of fibrils containing aggregates of actin microfilaments; in older segments the movement can be related to single, uniformly polarised, fibrils. Circulatory flow is maintained at the proximal end by the looping of the fibrils in the grain or at callose plugs. Such loops do not occur at the apex, where entering organelles undergo random movement before becoming associated with basipetal streams. Vegetative nuclei and generative cells interact with several fibrils, and it is suggested that they are held in the leading part of the protoplast in unstable equilibrium between acropetal and basipetal forces. Constantly changing form, especially of the vegetative nucleus, is one consequence of these varying stresses. Possible analogies with the intracellular motility system of the giant cells of the Characeae are noted, and it is suggested that lipid globuli and other nonorganellar bodies may be transported in the pollen tube by association with myosin-bearing membranes similar to those involved in endoplasm movement in the characean cells.     

The environmental movement and its critics

The history and nature of the new environmental movement in the United States are reviewed. Since understanding of a social movement is enhanced by learning the views and perceptions of outsiders, the continuing debate between the environmental movement and its critics is examined. First, disagreements over the nature and the severity of the so-called environmental crisis are described. Second, the ideological differences between environmentalists and their critics are reviewed, particularly their contrasting views of man, society, nature, and economic growth. Finally, the political critique of the movement is examined, with attention given to the composition of the membership, the alleged superficiality of its proposed solutions to environmental problems, and the alleged discrimination against both poor people in the United States and the poor nations.     

Daily and hourly movement of male desert-dwelling elephants

The daily and hourly movements of eight male desert-dwelling elephants of various ages (12–45 years old) were determined hourly by global positioning system (GPS)/telemetry collars during the wet, cold dry and hot dry seasons of 2006 in northwest Namibia. The average daily movement in the wet season was greater than that observed during either the cold dry or the hot dry seasons. A similar difference was also observed for the movement rates, with the highest average rate of hourly movement recorded during the wet season. The diurnal movements (both distance and rate) were greater than those in the nocturnal hours during the wet season, whilst during the cold dry and hot dry season the reverse was true. The daily cycle of movement also changed seasonally, with greatest movement rates observed during the wet season between 11.00–20.00 hours, during the cold dry season between 14.00–21.00 hours; and between 04.00–11.00 hours during the hot dry season. Periods of decreased movement rates were observed between 09.00–10.00 and 02.00–03.00 hours in the wet season; 03.00–06.00 and 11.00–13.00 hours in the cold dry season; and 01.00–03.00 and 12.00–14.00 hours during the hot dry season.     

Molecular fluctuation in living cells

The concept of molecular fluctuation in living cells is introduced. Many apparently different experi-mental facts in living cells, including the velocity non-uniformity of organelle movement, the saltatory movement of transport vesicles in axoplasmic transport, the chromosome oscillation during metaphase in mitosis and the pauses in the chromosome movement during anaphase are explained using a unified viewpoint. A method of determination of average number of the attached motor protein molecules from the experimental data is also proposed.     

Patellins 3 and 6, two members of the Plant Patellin family,interact with the movement protein of Alfalfa mosaic virus and interfere with viral movement

Movement proteins (MPs) encoded by plant viruses interact with host proteins to facilitate or interfere with intra‐ and/or intercellular viral movement. Using yeast two‐hybrid and bimolecular fluorescence complementation assays, we herein present in vivo evidence for the interaction between Alfalfa mosaic virus (AMV) MP and Arabidopsis Patellin 3 (atPATL3) and Patellin 6 (atPATL6), two proteins containing a Sec14 domain. Proteins with Sec14 domains are implicated in membrane trafficking, cytoskeleton dynamics, lipid metabolism and lipid‐mediated regulatory functions. Interestingly, the overexpression of atPATL3 and/or atPATL6 interfered with the plasmodesmata targeting of AMV MP and correlated with reduced infection foci size. Consistently, the viral RNA levels increased in the single and double Arabidopsis knockout mutants for atPATL3 and atPATL6. Our results indicate that, in general, MP–PATL interactions interfere with the correct subcellular targeting of MP, thus rendering the intracellular transport of viral MP‐containing complexes less efficient and diminishing cell‐to‐cell movement.     

CyberKnife beam output factor measurements: A multi-site and multi-detector study

PurposeNew promising detectors are available for measuring small field size output factors (OFs). This study focused on a multicenter evaluation of two new generation detectors for OF measurements on CyberKnife systems.MethodsPTW-60019 microDiamond and W1 plastic scintillation detector (PSD) were used to measure OFs on eight CyberKnife units of various generations for 5–60 mm fixed cones. MicroDiamond and PSD OF were compared to routinely used silicon diodes data corrected applying published Monte Carlo (MC) factors. PSD data were corrected for Čerenkov Light Ratio (CLR). The uncertainties related to CLR determination were estimated.ResultsConsidering OF values averaged over all centers, the differences between MC corrected diode and the other two detectors were within 1.5%. MicroDiamond exhibited an over-response of 1.3% at 7.5 mm and a trend inversion at 5 mm with a difference of 0.2%. This behavior was consistent among the different units. OFs measured by PSD slightly under-responded compared to MC corrected diode for the smaller cones and the differences were within 1%. The observed CLR variability was 2.5% and the related variation in OF values was 1.9%.ConclusionThis study indicates that CyberKnife microDiamond OF require corrections below 2%. The results are enhanced by the consistency observed among different units. Scintillator shows a good agreement to MC corrected diode but CLR determination remains critical requiring further investigations. The results emphasized the value of a multi-center validation over a single center approach.     

Mechanism for the small-scale movement of carbon among estuarine habitats: organic matter transfer not crab movement

In theory, carbon is highly mobile in aquatic systems. Recent evidence from carbon stable isotopes of crabs (Parasesarma erythrodactyla and Australoplax tridentata), however, shows that in subtropical Australian waters, measurable carbon movement between adjacent mangrove and saltmarsh habitats is limited to no more than a few metres. We tested whether the pattern in crab δ¹³C values across mangrove and saltmarsh habitats was explained by crab movement, or the movement of particulate organic matter. We estimated crab movement in a mark–recapture program using an array of pitfall traps on 13 transects (a total of 65 traps) covering an area of 600 m² across the interface of these two habitats. Over a 19-day period, the majority of crabs (91% for P. erythrodactyla, 93% for A. tridentata) moved <2 m from the place of initial capture. Crab movement cannot, therefore, explain the patterns in δ¹³C values of crabs. δ¹³C values of detritus collected at 2-m intervals across the same habitat interface fitted a sigmoidal curve of a similar form to that fitting the δ¹³C values of crabs. δ¹³C values of detritus were 2–4‰ more depleted in saltmarsh (−18.5±0.6‰), and 4–7‰ more depleted in mangroves (−25.9±0.1‰) than δ¹³C values of crabs recorded previously in each habitat. Assimilation by crabs of very small detrital fragments or microphytobenthos, more enriched in ¹³C, may explain the disparity in δ¹³C values. Nevertheless, the pattern in δ¹³C values of detritus suggests that crabs obtain their carbon from up to several metres away, but without themselves foraging more then a metre or so from their burrow. Such detailed measurements of carbon movement in estuaries provide a spatially explicit understanding of the functioning of food webs in saltmarsh and mangrove habitats.     

气相色谱与触角电位检测器联用技术及其应用

介绍了气相色谱与触角电位检测器联用技术的工作原理、优点及其在昆虫性信息素或其它信息物质鉴定方面的应用。根据作者应用此技术进行赤松毛虫和桑尺蛾性信息素研究的经验 ,重点介绍了气相色谱与触角电位联用技术在实践操作中应注意的问题     

A novel procedure for the localization of viral RNAs in protoplasts and whole plants

Analysis of virus spread using co-expressed reporter proteins has provided important details on cell-to-cell and long-distance movement of viruses in plants. However, most viruses cannot tolerate insertion of large non-viral segments or loss of any open-reading frames, procedures required to detect viruses non-evasively. A technique used to localize mRNAs intracellularly in yeast has been modified for detection of viral RNAs in whole plants. The technique makes use of the binding of the coat protein of MS2 bacteriophage (CPMS2) to a 19 base hairpin (hp). A fusion protein, consisting of the CPMS2, green fluorescent protein (GFP), and a nuclear localization signal (NLS), was nuclear-localized upon transient expression in protoplasts. However, addition of the hp to the 3' untranslated region of Turnip crinkle virus (TCV-hp) and co-transfection of the virus and fusion protein construct into protoplasts resulted in the re-location of GFP to the cytoplasm. Neither the insertion of the hp nor the interaction with the fusion protein impaired any viral functions. Transgenic plants expressing the GFP-NLS-CPMS2 fusion protein were generated, and GFP was detected in nuclei of young plant cells. Foci of GFP cytoplasmic fluorescence were detected in TCV-hp-inoculated leaves at 2 days post-inoculation. Later, GFP was detected in young leaves near the midvein and in the base (support) cells of trichomes in the vicinity of secondary and tertiary veins. In older leaves, cytoplasmic GFP could be visualized throughout many of the leaves. This technique should be amenable for detection of any virus with a transformable plant (or animal) host and may also prove useful for localizing properly engineered host RNAs.     

1998 ISEK Congress Keynote Lecture: Multi-muscle control in human movements

It has been suggested that the coordination of the activity of multiple muscles results from the comparison of the actual configuration of the body with a referent configuration specified by the nervous system so that the recruitment and gradation of the activity of each skeletal muscle depend on the difference between these two configurations. Active movements may be produced by the modification of the referent configuration. The hypothesis predicts the existence of a global minimum in electromyographic (EMG) activity of multiple muscles during movements involving reversals in direction. This prediction was tested in five subjects by analysing movements resembling the act of reaching for an object placed beyond one's reach from a sitting position. In such movements, initially sitting subjects raise their body to a semi-standing position and then return to sitting. Consistent with the hypothesis is the observation of a global minimum in the surface EMG activity of 16 muscles of the arm, trunk and leg at a specific phase of the movement. When the minimum occurred, EMG activity of each muscle did not exceed 2–7% of its maximal activity during the movement. As predicted, global EMG minima occurred at the phase corresponding to the reversal in movement direction, that is, during the transition from raising to lowering of the body. The global EMG minimum may represent the point at which temporal matching occurs between the actual and the referent body configurations. This study implies a specific link between motor behavior and the geometric shape of the body modified by the brain according to the desired action.     

Effect of Soil Texture and the Clay Component on Migration of Meloidogyne incognita Second-stage Juveniles

The vertical migration of M. incognita juveniles introduced at 20 cm from the roots was studied in five natural soils, 100% silica sand, 95% silica sand with 5% clay, 90% silica sand with 10% clay, and 95% silica sand with 5% clay as a concentrated layer. In natural soils the percentage of juveniles capable of migrating 20 cm and penetrating the roots decreased when the percentage of clay and silt increased. No migration occurred in silica sand without clay particles; when 5 or 10% of clay were mixed to silica sand, 34 and 26%, respectively, of the juveniles were able to migrate 20 cm. Clay separated from silica sand in which tomatoes were grown was attractive for juveniles. It is suggested that clay particles aid in the migration of root-knot juveniles over long distances to plant roots by absorbing and holding root exudates or bacterial by-products which form a concentration gradient enabling nematodes to locate roots.     

Chloroplast movement in Mougeotia induced by blue light pulses

The profile-to-face chloroplast movement in the green alga Mougeotia has been induced by strong blue and near-ultraviolet light pulses (6 J m^-2). Simultaneously, strong red or far-red light (10 W m^-2) was applied perpendicularly to the inducing beam. The response was measured photometrically. Against the far-red background the reciprocity law was found to hold for pulse durations varying two orders of magnitude. The action spectrum exhibited a maximum near 450 nm and a distinct increase in near-ultraviolet. The time-course and the spectral dependence of pulse responses of chloroplasts in Mougeotia were similar to those recorded for other plants which are sensitive only to blue. This points to an alternative sensor system active in the short-wavelength region in addition to the phytochrome system.Abbreviations FR far-red light - Pr red absorbing form of phytochrome - Pfr far-red absorbing form of phytochrome - R red light This paper is dedicated to the memory of Professor Jan Zurzycki     

Leaflet Movement of Robinia pseudoacacia in Response to a Changing Light Environment

Diurnal and nocturnal leaflet movement of black locust （Robinia pseudoacacia L.） was investigated under three light schemes： 100% natural irradiance, 50% shading, and 90% shading. Changes in leaf mid-vein angle were described by measurements of two planes： （i） β, the angle formed by the bottom of the petiolule and its relation to the horizontal plane; and （ii） θ, the angle between the petiolule and the main leaflet vein. The two highest light regimens had a significant effect on β. Variation in β tends to make the leaflet more erect, thereby minimizing any negative impact of high irradiance on leaf lamina. Light-dark rhythms induced variation in θ （termed nyctinastic movement）. Nyctinastic movement is important during the low light levels experienced by leaflets in early morning and late afternoon. At low light levels, the leaflet stopped nyctinastic movement and θ was fixed at an angle that may have enabled the leaf lamina to maximize light interception. After the light-dark cycle was reestablished, nyctinastic movement was restored. Taken together, our results suggest that irradiance induces variation in β leading to diurnal leaflet movement （diaheliotropism）, whereas the light-dark cycle influences θ, which results in nocturnal leaflet movement. Both angles are important for describing patterns of leaf movement in R. pseudocacia.     

HPLC determinations of enantiomeric ratios

Evaporative light-scattering detection (ELSD) is widely applied in the HPLC analysis of organic compounds lacking a UV chromophore. However, this detection method is generally unsuitable for determination of enantiomeric ratios (er). The er calculated from a UV trace and an ELS trace of the same compound differs significantly. Because of the nonlinear concentration response of the ELS detector, a compound with an er of 95:5 appears to be enantiomerically pure by ELS detection. It is possible to obtain a calibration curve and to calculate a correction factor, but this procedure is time consuming and therefore not very practical for routine analyses. In contrast, a charged aerosol detector allows a very accurate determination of the enantiomeric ratios. Like the ELS detection, the CA detection is independent of the chromophore properties of the substrate. Therefore, we recommend the use of CA instead of ELS detection for determination of the enantiomeric ratios of non-UV active compounds.     

Amoeba proteus displays a walking form of locomotion

This report deals with observations on the directional locomotion of amoeba before and after fixation and scanning electron microscopy. The study was aimed at visualization of the stepwise events of directional movements. After the analysis of the data it is proposed that the amoeba undergoes a sequence of movement events that can be defined as a walking form of locomotion.     

Movement of immature aquatic insects in a lotic habitat

The movement of immature insects up down and across Salem Creek, Ontario, was measured with traps and nets at two week intervals from January to December 1977. Drift of most taxa was more strongly correlated with water velocity from August to December than it was over the whole year. That of Baetis, however, was not correlated with water velocity and it was significantly greater at the side of the stream than at the centre from May to July. Upstream movement, as measured in three different ways, was small compared with drift, being only 2.1, 7.3 and 15.2 percent respectively.Upstream and across stream movements were not consistently different from one another, changes in their intensity apparently merely representing changes in numbers and behaviour of the animals. It is concluded therefore that upstream movement is only random movement.Colonization of empty sediment in trays on and above the substratum confirmed that most reoccupation of denuded areas is by drift. This supports the finding that drift is far geater than random wandering of the insects.