Dark Points Research Articles

A 34 year record of foredune evolution, Dark Point, NSW, Australia

Hesp, P.A., 2013. A 34 year record of foredune morphodynamics at Dark Point, NSW, Australia In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.)Incipient foredunes are formed by æolian deposition in plants on the backshore. They commonly evolve into established foredunes, and are present on many of the world's coasts, yet there are very few medium to long term studies on how they evolve and change over time. An incipient foredune suite has been monitored at Dark Point, NSW, Australia since 1978, providing a 34 year record of dune evolution and dynamics, and therefore representing one of the very few medium term foredune monitoring sites in the world.The foredune was initiated by the growth of a zone of discrete pioneer plant species (principally Spinifex) on the backshore following the destructive 1974–75 storms. Over a period of 24 years, 5 separate incipient foredunes developed as sediment was gradually returned to the surfzone and beach, and the beach prograded 70m. Sometime after 1998, storms cut back the seawardmost foredune and former foredunes were reactivated landwards of the 1998 foredune. This study demonstrates (i) how incipient foredunes form by both discrete seedling development, and seawards rhizome extension over time, (ii) how ramp and terrace morphologies eventually evolve into ridges, (iii) rates of beach accretion following storm erosion and backshore response, (iv) how wave erosion drives morphological changes and evolutionary sequences on foredunes, (v) the relationships between backshore height, foredune development and sea levels, and (vi) indications for the initiation and evolution of so-called ‘beach ridges'.

Responses of Trachelospermum asiaticum (Apocynaceae) seedlings to growth in a light intensity gradient

AbstractWe recorded the growth of 24 seedlings of Trachelospermum asiaticum, a root climber, placed between a light source and a wall. Shoot length of seedlings planted at the brightest points nearly matched the distance the shoot tips moved toward the wall surface. In contrast, although the seedlings planted at the darkest points did elongate, the tips moved an average distance of only 0.4 cm. Creeping shoots of T. asiaticum planted in brighter environments exhibit negative phototropism, which encourages them to grow rapidly toward dark places, allowing them to reach supporting hosts faster than those that germinate close to the host.

Hexavalent Chromium Reduction and Accumulation by Acinetobacter AB1 Isolated from Fez Tanneries in Morocco

Hexavalent chromium reduction and accumulation by Acinetobacter AB1 isolated from Fez tanneries effluents were tested. The effects of some environmental factors such as pH, temperature, and exposure time on Cr(VI) reduction and resistance were investigated. We found that this strain was able to resist to concentrations as high as 400mg/l of Cr(VI). Moreover, pH 10 and the temperature 30°C constitute favourable conditions to the growth and reduction of Acinetobacter AB1. Complete reduction of Cr(VI) was observed at low initial Cr(VI) concentrations of 50mg/l after 72h of incubation. Furthermore, Transmission electron microscope (TEM) analysis showed morphological changes in AB1 strain due 48H exposure to 100mg/l chromate concentration and revealed circular electron dense (dark black point) inclusion within the cell cytoplasm suggesting chromium deposition within the cells.

Investigation of the Impact of Surrounding Light on Monitor’ Color Showing

Under surrounding light, the color showing on monitor's surface is produced by its emitting light and the reflected part of surrounding light by the surface. Utilizing the color characterizing relation of monitor, the actual color showing performances of two monitors in color gamuts and tone curves under different conditions of surrounding light were investigated. The experiment results showed that the luminance values of some dark colors and black point could increase with the illuminance increase of surrounding light, resulting in the compress in gamut within the color space area. And the same phenomena appeared in every color tone curves. But the change in lightness value of the white point was much smaller relatively. And the results revealed simultaneously that the compress extent could not only correlate directly with the illuminance of surrounding light, but also with the relative increase in black point lightness, further, with the intrinsic emitting light and reflecting capability of the screen surface.

Imaging of magnetically labeled single-cell by 7.0 T MR

To detect magnetically labeled single cells in vitro by using 7.0T MRI system and to optimize the parameters used for labeled cell imaging. The endothelial cells ECV-304 were incubated with self-synthesized Fe2O3-PLL Prussian blue stain was employed for identifying intracellular irons. Agarose phantoms of dispersed labeled cells were made with an cell concentration of 2 x 10(3)/ml. 3D-FLASH sequence was employed for the detection of single cells and the cell concentration calculated by counting the number of dark points in MR images; The investigators compared the effects of gradient echo sequence (2D-FLASH) and spin echo sequence (MSME) upon the imaging of magnetically labeled single cells; Also the effects of different echo times (Es) and resolutions of magnetic nanoparticle relaxation upon the imaging of cells were analyzed. The endothelial cells ECV-304 were labeled successfully and the labeling efficiency reached almost 100%. Prussian blue staining of Fe2O3-PLL labeled cells revealed the cytoplasmic presence of iron. Single cells were detected as isolated dark points and the cell concentration corresponded with the actual data. The 2D-FLASH sequence had a much stronger T2* effect than MSME sequence in single cell detection. The T2* effect increased with the prolongation of TE. The signal loss fell significantly as the resolution decreased. And it reached almost zero when the voxel size reached 200 microm3. 7.0T MR system is able to detect magnetically labeled single cells. The optimization of imaging sequences enhances the sensitivity of magnetically labeled single cells. Thus it provides a better method for in vivo detection of single cells.

Model-independent analysis of dark matter points to a particle mass at the keV scale

We present a model independent analysis of dark matter (DM) both decoupling ultra relativistic (UR) and non-relativistic (NR) based in the phase-space density D = rho_{DM}/sigma^3_{DM}. We derive explicit formulas for the DM particle mass m and for the number of ultra relativistic degrees of freedom g_d at decoupling. We find that for DM particles decoupling UR both at local thermal equilibrium (LTE) and out of LTE, m turns to be at the keV scale. For example, for DM Majorana fermions decoupling at LTE the mass results m ~ 0.85 keV. For DM particles decoupling NR, sqrt{m T_d} results in the keV scale (T_d is the decoupling temperature) and the m value is consistent with the keV scale. In all cases, DM turns to be cold DM (CDM). Also, lower and upper bounds on the DM annihilation cross-section for NR decoupling are derived. We evaluate the free-streaming (Jeans') length and Jeans' mass: they result independent of the type of DM except for the DM self-gravity dynamics. The free-streaming length today results in the kpc range. These results are based on our theoretical analysis, astronomical observations of dwarf spheroidal satellite galaxies in the Milky Way and N-body numerical simulations. We analyze and discuss the results on D from analytic approximate formulas both for linear fluctuations and the (non-linear) spherical model and from N-body simulations results. We obtain in this way upper bounds for the DM particle mass which all result below the 100 keV range.

Intermediate Mass Black Holes and Nearby Dark Matter Point Sources: A Critical Reassessment

Dark matter (DM) "minispikes" around intermediate mass black holes are sometimes quoted as one of the most promising targets for indirect DM searches. Here, we stress that existing cosmic ray data place severe constraints on the possibility to detect DM annihilation signals from these objects in gamma rays; observational prospects for neutrinos or charged cosmic rays seem even worse. Similar bounds severely constrain the possibility that the excess in the cosmic ray positron or electron flux recently reported by PAMELA/ATIC could be due to a nearby point source like a DM clump or minispike.

Can you be BLACK and Work Here?: Social Justice Activist Organizing and Black Aurality

How can social justice organizations organize without marginalizing identities and concurrently tend to the blindspots that arise when intersectional identities are not taken into account? Black (here, BLACK) music, with its rudimentary foundation in black sound, gives a framework for organizing without institutionalization, structuring without strictures. The aurality evident in black sound resists: moans, hollers, shrieks, cries, falsettos, melisma, modulations, inversions, choruses, repetitions, improvisations, and rhythms defy limitation, the strictures of subjectivity, structures of power, demeaning discourses. This essay gestures toward a theory of social justice praxis based on black sound. It will demonstrate that organizations should be intentionally attentive to the aurality, in this case, of black sound and how this sound voices the problematics of institutionalization. Black sound creates “dark points of possibility” for insurgent action, for social justice activism that fully accounts for the intersectionalities white social justice organizations often occlude, that must be heard outside the bewildering gaze of white, gay normativity.

Revisiting the parametrization of equation of state of dark energy via SNIa data

In this paper, we revisit the parametrizations of the equation of state of dark energy and point out that comparing merely the χ2 of different fittings may not be optimal for choosing the ‘best’ parametrization. Another figure of merit for evaluating different parametrizations based on the area of the w(z) −z band is proposed. In light of the analysis of some two-parameter parametrizations and models based on available SNIa data, the area of w(z) −z band seems to be a good figure of merit, especially in the situation that the value of χ2min for different parametrizations are very close. Therefore, we argue that both the area of the w(z) −z band and χ2min should be synthetically considered for choosing a better parametrization of dark energy in the future experiments.

Growth characteristics of the cyanobacterium Nostoc flagelliforme in photoautotrophic, mixotrophic and heterotrophic cultivation

Nostoc flagelliforme is a terrestrial cyanobacterium with high economic value. Dissociated cells separated from a natural colony of N. flagelliforme were cultivated for 7 days under either phototrophic, mixotrophic or heterotrophic culture conditions. The highest biomass, 1.67 g L−1 cell concentration, was obtained under mixotrophic culture, representing 4.98 and 2.28 times the biomass obtained in phototrophic and heterotrophic cultures, respectively. The biomass in mixotrophic culture was not the sum as that in photoautotrophic and heterotrophic cultures. During the first 4 days of culture, the cell concentration in mixotrophic culture was lower than the sum of those in photoautotrophic and heterotrophic cultures. However, from the 5th day, the cell concentration in mixotrophic culture surpassed the sum of those obtained from the other two trophic modes. Although the inhibitor of photosynthetic electron transport DCMU [3-(3,4-dichlorophenyl)-1,1-dimethylurea] efficiently inhibited autotrophic growth of N. flagelliforme cells, under mixotrophic culture they could grow by using glucose. The addition of glucose changed the response of N.flagelliforme cells to light. The maximal photosynthetic rate, dark respiration rate and light compensation point in mixotrophic culture were higher than those in photoautotrophic cultures. These results suggest that photoautotrophic (photosynthesis) and heterotrophic (oxidative metabolism of glucose) growth interact in mixotrophic growth of N. flagelliforme cells.

Deriving consistent long-term vegetation information from AVHRR reflectance data using a cover-triangle-based framework

Long-term vegetation dynamics associated with climatic changes can be assessed using Advanced Very High Resolution Radiometer (AVHRR) red and near-infrared reflectance data provided that the data have been processed to remove the effects of non-target signal variability, such as atmospheric and sensor calibration effects. Here we present a new method that performs a relative calibration of reflectance data to produce consistent long-term vegetation information. It is based on a simple biological framework that assumes that the position of the vegetation cover triangle is invariant in reflectance space. This assumption is in fact an intrinsic assumption behind the commonly used Normalised Difference Vegetation Index (NDVI) and is violated when the NDVI is calculated from inadequately corrected reflectance data. In this new method, any temporal variability in the position of the cover triangle is removed by geometrically transforming the observed reflectance data such that two features of the triangle—the soil line and the dark point—are stationary in reflectance space. The fraction of Photosynthetically Active Radiation absorbed by vegetation (fPAR; 0.0–0.95) is then calculated, via the NDVI, from calibrated reflectances. This method was tested using two distinct, monthly AVHRR products for Australia: (i) the coarse-resolution, fully calibrated, partially atmospherically corrected PAL data (1981–1994); and (ii) the fine-resolution, fully calibrated, non-atmospherically corrected HRPT data (1992–2004). Results show that, in the 20-month period when the two datasets overlap (1992–1994), the Australia-wide, root mean square difference between the two datasets improved from 0.098 to 0.027 fPAR units. The calibrations have produced two approximately equivalent datasets that can be combined as a single input into time-series analyses. The application of this method is limited to areas that have a wide-enough variety of land-cover types so that the soil line and dark point are evident in the cover triangle in every image of the time-series. Another limitation is that the methodology performs only bulk, relative calibrations and does not remove the absolute effects of observation uncertainties. The simplicity of the method means that the calibration procedure can be easily incorporated into near-real-time operational remote-sensing environments. Vegetation information produced using this invariant-cover-triangle method is expected to be well suited to the analysis of long-term vegetation dynamics and change.

Gas exchange and photosynthetic water use efficiency in response to light, CO 2 concentration and temperature in Vicia faba

Light and temperature-response curves and their resulting coefficients, obtained within ecophysiological characterization of gas exchanges at the leaf level, may represent useful criteria for breeding and cultivar selection and required tools for simulation models aimed at the prediction of potential plant behaviour in response to environmental conditions. Leaf-scale gas exchanges, by means of an IRGA open-flow system, were measured in response to light intensity (8 levels from 0 up to 2000 micromol m(-2) s(-1)), CO(2) concentrations (ambient-350 micromol mol(-1) and short-term enriched-700 micromol mol(-1)) and air temperature (from 7 up to 35 degrees C) on three Vicia faba L. genotypes, each representing one of the three cultivated groups: major, equina and minor. The net assimilation rate response to light intensity was well described by an exponential rise to max function. The short-term CO(2) enrichment markedly increased the values of light response curve parameters such as maximum photosynthetic rate (+80%), light saturation point (+40%) and quantum yield (+30%), while less homogenous behaviour was reported for dark respiration and light compensation point. For each light intensity level, the major and minor genotypes studied showed assimilation rates at least a 30% higher than equina. The positive effects of short-term CO(2) enrichment on photosynthetic water use efficiency (WUE) indicate a relevant advantage in doubling CO(2) concentration. In the major and minor genotypes studied, similar assimilation rates, but different WUE were observed. The optimum leaf temperature for assimilation process, calculated through a polynomial function, was 26-27 degrees C and no relevant limitations were observed in the range between 21 and 32 degrees C. Analysis at the single leaf level provided both rapid information on the variations in gas exchange in response to environmental factors and selection criteria for the screening of genotypes.

Ultrastructure of sporulation in Haplosporidium armoricanum

An ultrastructural study was carried out on the tissues of an oyster (Ostrea edulis), heavily infected with Haplosporidium armoricanum, that had been fixed in Carson's fixative. The well-fixed tissues revealed details of sporulation and of the spores, which had not been previously reported from H. armoricanum. These include the initial presence of sparse haplosporosomes after thickening of the plasma membrane in early sporonts, division of sporont nuclei by multiple fission, cup-like indentations in the nuclear surface associated with putative nuclear material in both the sporonts and spores, and cytoplasmic multi-vesicular bodies in the cytoplasm of sporonts and spores. The spore wall and operculum were formed from a light matrix that occurred in short cisternae of smooth endoplasmic reticulum in the episporoplasm, and parallel bundles of microfibrils were present in some spores. Spores were rarely bi-nucleate with the nuclei occurring as a diplokaryon, with putative nuclear material at the junction of the 2 nuclei. Nuclear membrane-bound Golgi (NM-BG) cisternae were common in spores, and they appeared to synthesise a light granular material into lysosome-like granules. Dense bodies similar to those reported from H. lusitanicum, H. pickfordi and H. monforti occurred in, or outside, the peripheral endosporoplasm, which was closely apposed to the spore wall. Spore haplosporosomes were frequently axehead-shaped, more like those of H. costale than those previously reported from H. armoricanum, and in some haplosporosomes there was a small round lucent patch with a dark point near the centre of the lucent patch. Overall, H. armoricanum appears to be closely related to H. costale and Bonamia spp. Although the endosporoplasm of H. armoricanum has NM-BG and it resembles the uni-nucleate stage, it appears to be unlikely that they are the same, as the axehead-shaped haplosporosomes of the spore differ considerably from the spherical haplosporosomes of vegetative stages.

Differential Attention-Dependent Response Modulation across Cell Classes in Macaque Visual Area V4

The cortex contains multiple cell types, but studies of attention have not distinguished between them, limiting understanding of the local circuits that transform attentional feedback into improved visual processing. Parvalbumin-expressing inhibitory interneurons can be distinguished from pyramidal neurons based on their briefer action potential durations. We recorded neurons in area V4 as monkeys performed an attention-demanding task. We find that the distribution of action potential durations is strongly bimodal. Neurons with narrow action potentials have higher firing rates and larger attention-dependent increases in absolute firing rate than neurons with broad action potentials. The percentage increase in response is similar across the two classes. We also find evidence that attention increases the reliability of the neuronal response. This modulation is more than two-fold stronger among putative interneurons. These findings lead to the surprising conclusion that the strongest attentional modulation occurs among local interneurons that do not transmit signals between areas.

A comparison of the physiology, anatomy and ribosomal DNA in alpine and subalpine populations of the lichen Nephroma arcticum—the effects of an eight-year transplant experiment

Thalli of Nephroma arcticum were transplanted between and within a high-elevation alpine heath (1100 m) and a low-elevation subalpine mountain birch forest (380 m) in northern Swedish Lapland and harvested after eight years. Statistically significant differences (P < 0.05) were found between control samples for dark respiration rates, photon use efficiencies (apparent quantum yields) and light compensation points (all were higher in the high-altitude population). The following traits were significantly affected by transplanting: (1) epicortex thickness, (2) upper cortex thickness in the low-altitude population, (3) maximum photosynthetic rates, (4) dark respiration rates and (5) light compensation point. Of these malleable traits, all reduce the differences between the controls although there seems to be over-compensation in maximum net photosynthesis and under-compensation in dark respiration rate of the low-altitude population. Conservative traits, i.e., those that did not change significantly with transplantation were: (1) thallus thickness, (2) algal layer thickness, (3) algal cell diameter and (4) light saturation level. Small, yet significant differences in anatomy and physiology suggest that an ecotypic differentiation was established although the two internal transcribed DNA spacers ITS 1 and ITS 2 showed no corresponding variation between the populations.

Critical Role of Electrostatic Interactions of Amino Acids at the Cytoplasmic Region of Helices 3 and 6 in Rhodopsin Conformational Properties and Activation

The cytoplasmic sides of transmembrane helices 3 and 6 of G-protein-coupled receptors are connected by a network of ionic interactions that play an important role in maintaining its inactive conformation. To investigate the role of such a network in rhodopsin structure and function, we have constructed single mutants at position 134 in helix 3 and at positions 247 and 251 in helix 6, as well as combinations of these to obtain double mutants involving the two helices. These mutants have been expressed in COS-1 cells, immunopurified using the rho-1D4 antibody, and studied by UV-visible spectrophotometry. Most of the single mutations did not affect chromophore formation, but double mutants, especially those involving the T251K mutant, resulted in low yield of protein and impaired 11-cis-retinal binding. Single mutants E134Q, E247Q, and E247A showed the ability to activate transducin in the dark, and E134Q and E247A enhanced activation upon illumination, with regard to wild-type rhodopsin. Mutations E247A and T251A (in E134Q/E247A and E134Q/T251A double mutants) resulted in enhanced activation compared with the single E134Q mutant in the dark. A role for Thr(251) in this network is proposed for the first time in rhodopsin. As a result of these mutations, alterations in the hydrogen bond interactions between the amino acid side chains at the cytoplasmic region of transmembrane helices 3 and 6 have been observed using molecular dynamics simulations. Our combined experimental and modeling results provide new insights into the details of the structural determinants of the conformational change ensuing photoactivation of rhodopsin.

INDIRECT SOMATIC EMBRYOGENESIS OF ACTINIDIA CHINENSIS PL.A FEMALE HAYWARD VARIETY CASE

The original cradle of Actinidia chinensis PL. is China. This species has been introduced in the botanical gardens of Paris Museum and the tests garden of Algiers (Algeria). This plant is commercially cultivated since more then thirty years in New Zealand. Tests of indirect somatic embryogenesis have been achieved on the Hayward variety. The results have shown that the calluses are green beige and very crumbly with often green dark small points. The calluses led in a MS media + 4.5 µ M of 2.4-D and 4.65 µ M of kinetin in 12g/l Agar are dry in appearance because of the strong Agar content and the weaker water potential. The most elevated relative average growth rate (RGR) is obtained on a MS media + 4.5 µ M (2.4-D) and 4.65 µ M kinetin in 8 g/l of Agar. The histological analysis revealed the presence of various structures suggesting a bourgeonnement process. Among the structures observed many meristematic diffuse masses with occasionally center visible tracheids and fibbers.

Gazneli Ordusunda Görev Alan Hintliler

Gazneli Devleti kurulduktan hemen sonra hükümdarlar Hindistan seferlerine başlamış ve bu kıtadaki insan kaynağından askeri yönde de faydalanmışlardır. Bu konuda önemli bilgiler Prof. Dr. C.E. Bosworth tarafından "Ghaznevid Military Organisation" başlıklı makalesinde ve Gazneliler ile ilgili iki kitabında açıklamıştır. Ancak Prof. Bosworth tarafından verilen bilgilerde bazı eksiklikler göze çarpmaktadır. Biz bu makalemizde hem eksikleri tamamlamaya, hem de bu konudaki olayları hatırlatmaya çalışacağız. Eksiklikleri tamamlarken en önemli kaynağımız ise, Beyhakî'nin Tarih-i Beyhakî adlı eseri olacaktır. Bu eser elimize eksik ulaşmasaydı, muhakkak ki, konumuz hakkında daha etraflı bilgi sahibi olacaktık.

Nova espécie de Pimelodus (Siluriformes, Pimelodidae) dos rios Tapajós e Tocantins, Brasil

Pimelodus tetramerus sp. nov. difere das outras espécies de Pimelodus Lacepède por sua coloração típica, que consiste de quatro faixas escuras sobre os lados do corpo, a primeira, mais dorsal, iniciando logo após o final da placa pré-dorsal e terminando no final da base da nadadeira adiposa; a segunda, mais larga que a primeira, logo acima da linha lateral, percorre desde a borda lateral do processo supra-occipital até a base da nadadeira caudal. Ambas faixas estão fragmentadas em sua porção anterior, formando pontos escuros que, ocasionalmente, podem estar unidos, compondo um padrão vermiculado. Tais pontos escuros e/ou padrão vermiculado se distribui sobre a região pré-dorsal e cabeça. A terceira faixa, tão larga quanto a segunda, logo abaixo da linha lateral, inicia junto à região superior do processo pós-cleitral e estende-se até a base da nadadeira caudal e a quarta, de menor comprimento, podendo estar fraca ou ausente, inicia-se logo abaixo do processo pós-cleitral e finaliza até próximo à nadadeira pélvica. Além disso, constituem caracteres diagnósticos da nova espécie a presença de uma estreita faixa clara sobre a linha lateral, com aproximadamente 1/3 da largura da terceira faixa escura, e a presença de uma barra escura percorrendo longitudinalmente o lobo ventral da nadadeira caudal. A nova espécie compartilha o forâmen trigeminal tripartido com outras espécies de pimelodídeos.

Response of Growth Dynamics of Two Spring Geophytes to Light Regime in a Lime-Beech Forest

Biomass accumulation, leaf longevity and growth rate of two spring forest geophytes, Scilla bifolia L. and Arum maculatum L. were estimated separately for three size groups within each population of these species. Despite the differences in leaf longevity, both species showed a similar pattern of biomass accumulation in relation to their phenologies and reproductive demands. Eco-physiological acclimation to changing light environment was assumed through photosynthetic parameters and dynamics of leaf area index in the predominant size group of each species. A light response curve was measured under natural light for each species through the continuum of its phenology to quantify the photosynthetic photon flux density at light saturation, light-saturated photosynthetic rate, light compensation point, and dark respiration. Light-saturated assimilation per leaf area basis, dark respiration rate and light compensation points were significantly higher in S. bifolia relative to A. maculatum. However, the acclimation of photosynthesis that would respond to light changes in environment was not found in S. bifolia. In contrast, in A. maculatum a marked shift in the light dependence of photosynthesis through the season was noticed, which resulted in a strong photosynthetic acclimation to the low-light conditions. Accompanied by significant leaf area index, this efficient low-light photosynthesis enabled greater leaf longevity, and consequently longer accumulative period to A. maculatum. From the different parameters that we determined (both photosynthetic acclimation and growth strategy) it would appear that these species belong to two distinct subgroups: S. bifolia to the early and A. maculatum to the late vernals. (Managing editor: Ya-Qin)