High surface brightness dwarf galaxies in the Fornax cluster

We describe a search for compact dwarf galaxies in the Fornax cluster using the FLAIR spectrograph on the UK Schmidt Telescope. We measured radial velocities of 453 compact galaxies brighter than B-T approximate to 17.3 and found seven new compact dwarf cluster members that were not classified in previous surveys as members of the cluster. These are amongst the most compact, high surface brightness dwarf galaxies known. The inclusion of these galaxies in the cluster does not change the total luminosity function significantly, but they are important because of their extreme nature; one in particular appears to be a dwarf spiral. Three of the new dwarfs have strong emission lines and we identify them as blue compact dwarfs (BCDs), doubling the number of confirmed BCDs in the cluster. We also determined that none of the compact dwarf elliptical (M32-like) candidates is in the cluster, down to an absolute magnitude M-B = -13.2. We have investigated the claim of Irwin et al. that there is no strong relation between surface brightness and magnitude for the cluster members and find some support for this for the brighter galaxies (B-T < 17.3), but fainter galaxies still need to be measured.

Surface topography and mixed-pixel effects on the simulated L-band brightness temperatures.

The impact of topography and mixed pixels on L-band radiometric observations over land needs to be quantified to improve the accuracy of soil moisture retrievals. For this purpose, a series of simulations has been performed with an improved version of the soil moisture and ocean salinity (SMOS) end-to-end performance simulator (SEPS). The brightness temperature generator of SEPS has been modified to include a 100-m-resolution land cover map and a 30-m-resolution digital elevation map of Catalonia (northeast of Spain). This high-resolution generator allows the assessment of the errors in soil moisture retrieval algorithms due to limited spatial resolution and provides a basis for the development of pixel disaggregation techniques. Variation of the local incidence angle, shadowing, and atmospheric effects (up- and downwelling radiation) due to surface topography has been analyzed. Results are compared to brightness temperatures that are computed under the assumption of an ellipsoidal Earth.

Low environmental impact bleaching sequences for attaining high brightness level with eucalyptus SPP pulp

The alternatives used for minimizing the usage of chlorine dioxide in bleaching sequences included a hot acid hydrolysis (Ahot) stage, the use of hot chlorine dioxide (Dhot) and ozone stages at medium consistency and high consistency (Zmc and Zhc), in addition to stages with atmospheric hydrogen peroxide (P) and pressurized hydrogen peroxide (PO). The results were interpreted based on the cost of the chemical products, bleaching process yields and on minimizing the environmental impact of the bleaching process. In spite of some process restrictions, high ISO brightness levels were kept around 90 % brightness. Additionally, the inclusion of stages like acid hydrolysis, pressurized peroxide and ozone in the bleaching sequences provided an increase in operating flexibility, aimed at reducing environmental impact (ECF Light). The Dhot(EOP)D(PO) sequence presented lower operating cost for ISO brightness above 92 %. However, this kind of sequence was not allowed for closing the wastewater circuit, even partially. For ISO brightness level around 91%, the AhotZhcDP sequence presented a lower operating cost than the others

Brightness of multilayer boards

A good appearance of a package enhances the sale of the product. The packing gives information about the content and instructions for the usage. In this master’s thesis, the optical properties of multilayer packaging board is studied. Especially means of increasing brightness of the multilayer board are evaluated. In the literature part, the effect of different factors on optical properties of a multilayer board are evaluated with the help of light scattering and absorption coefficients. The Kubelka-Munk theory can be used also in modelling brightness of the multilayer board. A large variety of different process factors, chemical aids and machine variables affect optical properties of board. In the experimental part, different methods to increase brightness of a 3-layer board were evaluated. It was discovered that brightness variation of broke (30 % share of the center layer pulp) have only minor influence on brightness of the board. The brightness variation must be high, roughly 9 % in order to alter brightness of the board by 1 %. Higher brightness can be achieved by bleaching the pulp, which holds the largest share of the center layer pulp. Here, 2,6 % increase in brightness of the pulp (60 % share of the center layer pulp) increased brightness of the board by 1 %. In a trial run at a board machine, there was no indication of decreased bulk of the board due to extended bleaching of the pulp. With pulp dyeing appearance and optical properties of a multilayer board can be influenced. By using bluish dyes the natural yellowness of pulps can be decreased and impression of whiteness is then increased. Brightness may deteriorate though, because of increasing light absorption of the dyed pulps. When the yellowness comes from the center layer pulp, the dye should be introduced there. Then the brightness decreasing effect of the dye decreases brightness of the board less. It was noticed that it is more important to maintain brightness of the top layer than brightness of the center layer, because the top layer pulp affects on brightness of the board the most. By introducing fillers into the top layer of a multilayer board it is possible to increase brightness of the board. Fillers with the highest light scattering increased the brightness of the board the most. Increasing light scattering increases brightness and also opacity. Higher opacity in the top layer decreases also the darkening effect of the center layer. Calcinated kaolin and PCC was found to increase the light scattering of the top layer the most at the filler comparison. Introducing fillers into the top layer of multilayer board may decrease bulk and modulus of elasticity of the top layer. This could lead to deteriorated bending stiffness.

Water circulations for effective bleaching of high-brightness mechanical pulps

The amount of water available is usually restricted, which leads to a situation where a complete understanding of the process, including water circulations and the influence of water components, is essential. The main aim of this thesis was to clarify the possibilities for the efficient use of residual peroxide by means of water circulation rearrangements. Rearranging water circulations and the reduction of water usage may cause new problems, such as metal induced peroxide decomposition that needs to be addressed. This thesis introduces theoretical methods of water circulations to combine two variables; effective utilization of residual peroxide and avoiding manganese in the alkaline peroxide bleaching stage. Results are mainly based on laboratory and mill site experiments concerning the utilization of residual peroxide. A simulation model (BALAS) was used to evaluate the manganese contents and residual peroxide doses. It was shown that with optimum recirculation of residual peroxide the brightness can be improved or chemical costs can be decreased. From the scientific perspective, it was also very important to discover that recycled peroxide was more effective pre-bleaching agent compared to fresh peroxide. This can be due to the organic acids i.e. per acetic acid in wash press filtrate that have been formed in alkaline bleaching stage. Even short retention time was adequate and the activation of residual peroxide using sodium hydroxide was not necessary. There are several possibilities for using residual peroxide in practice regarding bleaching. A typical modern mechanical pulping process line consist of defibering, screening, a disc filter, a bleach press, high consistency (HC) peroxide bleaching and a wash press. Furthermore there usually is not a particular medium consistency (MC) pre-bleaching stage that includes additional thickening equipment. The most advisable way to utilize residual peroxide in this kind of process is to recycle the wash press filtrate to the dilution of disc filter pulp (low MC pre-bleaching stage). An arrangement such as this would be beneficial in terms of the reduced convection of manganese to the alkaline bleaching stage. Manganese originates from wood material and will be removed to the water phase already in the early stages of the process. Recycling residual peroxide prior to the disc filter is not recommended because of low consistencies. Regarding water circulations, the novel point of view is that, it would be beneficial to divide water circulations into two sections and the critical location for the division is the disc filter. Both of these two sections have their own priority. Section one before the disc filter: manganese removal. Section two after the disc filter: brightening of pulp. This division can be carried out if the disc filter pulp is diluted only by wash press filtrate before the MC storage tower. The situation is even better if there is an additional press after the disc filter, which will improve the consistency of the pulp. This has a significant effect on the peroxide concentration in the MC pre-bleaching stage. In terms of manganese content, it is essential to avoid the use of disc filter filtrate in the bleach press and wash press showers. An additional cut-off press would also be beneficial for manganese removal. As a combination of higher initial brightness and lower manganese content, the typical brightness increase varies between approximately 0.5 and 1% ISO units after the alkaline peroxide bleaching stage. This improvement does not seem to be remarkable, but as it is generally known, the final brightness unit is the most expensive and difficult to achieve. The estimation of cost savings is not unambiguous. For example in GW/TMP mill case 0.6% ISO units higher final brightness gave 10% savings in the costs of bleaching chemicals. With an hypothetical 200 000 ton annual production, this means that the mill could save in the costs of bleaching chemicals more than 400 000 euros per year. In general, it can be said that there were no differences between the behavior of different types of processes (GW, PGW, TMP and BCTMP). The enhancement of recycling gave a similar response in all cases. However, we have to remember that the utilization of residual peroxide in older mills depends a great deal on the process equipment, the amount of water available and existing pipeline connections. In summary, it can be said that processes are individual and the same solutions cannot be applied to all cases.

The role of bound chlorine in the brightness reversion of bleached hardwood kraft pulp

Our previous paper showed fragmentary evidence that pulp brightness reversion may be negatively affected by its organically bound chlorine (OX) content. A thorough investigation on eucalyptus kraft pulp led to the conclusion that OX increases reversion of certain pulps but this trend is not universal. Alkaline bleaching stages decrease reversion regardless of pulp OX content. Pulps bleached with high temperature chlorine dioxide revert less than those bleached with conventional chlorine dioxide in sequences ending with a chlorine dioxide stage but similarly in sequences ending with a final peroxide stage. The use of secondary condensate for pulp washing decreases reversion.

The effect of wood supply and bleaching process on pulp brightness stability

One hundred different 5.5-year-old Eucalyptus grandis x Eucalyptus urophylla wood clones were cooked to kappa number 15-17.5 and the resulting kraft pulps oxygen-delignified to kappa 9.5-11.5 under fixed conditions, except for chemical charges. Thirteen samples showing large variations in effective alkali requirement, pulp yield and O-stage efficiency and selectivity were selected for brightness reversion studies. These samples were bleached to 90-91% ISO by DEDD and DEDP sequences and their brightness stability and chemical characteristics determined. Heat reversion of the eucalyptus kraft pulps was strongly influenced by the wood supply, with brightness loss varying in the range of 2.1-3.6 and 0.8-1.7 %ISO for ODEDD and ODEDP bleached pulps, respectively. Pulps bleached by the ODEDP sequence showed reversion values 1.3-1.9 % ISO lower than those bleached by the ODEDD sequence. Pulp carbonyl content decreased by 35-40% during the final peroxide bleaching stage. Carbonyl and carboxyl groups correlated positively with brightness reversion, as did permanganate number and acid soluble lignin. Pulp final viscosity and metal and DCM extractives contents showed no significant correlation with brightness reversion. Pulping, oxygen delignification and ECF bleaching performances also showed no correlation with brightness reversion.

Magnesium hydroxide-based peroxide bleaching of high-brightness mechanical pulps

A high final brightness is desired in most paper and board products. This requires bleaching processes that are able to produce high-brightness pulps. Mechanical pulps are widely bleached for high brightness using alkaline hydrogen peroxide with traditional sodium hydroxide and sodium silicate as additives. With high doses however, peroxide bleaching causes high organic loads in the mill effluent and anionic trash carry-over to papermaking. To alleviate the problems that arise from the use of sodium-based additives in peroxide bleaching, interest in the use of alternative magnesium-based chemicals has increased. In this study, a new, technical high-purity magnesium hydroxide-based bleaching additive was evaluated on laboratory-scale, pilot-scale and mill-scale experiments and trials for its ability to produce a high brightness in peroxide bleaching without the known problems of sodium-based chemicals. The key findings of this study include: a high brightening potential of peroxide bleaching using the Mg(OH)2-based additive, significant reductions (40-70%) in all categories of environmental load, and cationic demand lowered by 60-70% in bleached pulp with no loss in strength properties or in sheet bulk. When used in TMP refiner bleaching, the Mg(OH)2-based additive resulted in savings in specific energy consumption and provided a good bleaching response.

Role of Low-level Mechanisms in Brightness Perception

Brightness judgments are a key part of the primate brain's visual analysis of the environment. There is general consensus that the perceived brightness of an image region is based not only on its actual luminance, but also on the photometric structure of its neighborhood. However, it is unclear precisely how a region's context influences its perceived brightness. Recent research has suggested that brightness estimation may be based on a sophisticated analysis of scene layout in terms of transparency, illumination and shadows. This work has called into question the role of low-level mechanisms, such as lateral inhibition, as explanations for brightness phenomena. Here we describe experiments with displays for which low-level and high-level analyses make qualitatively different predictions, and with which we can quantitatively assess the trade-offs between low-level and high-level factors. We find that brightness percepts in these displays are governed by low-level stimulus properties, even when these percepts are inconsistent with higher-level interpretations of scene layout. These results point to the important role of low-level mechanisms in determining brightness percepts.

An improved algorithm for generating global window brightness temperatures from multiple satellite infrared imagery

An improved algorithm for the generation of gridded window brightness temperatures is presented. The primary data source is the International Satellite Cloud Climatology Project, level B3 data, covering the period from July 1983 to the present. The algorithm rakes window brightness, temperatures from multiple satellites, both geostationary and polar orbiting, which have already been navigated and normalized radiometrically to the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer, and generates 3-hourly global images on a 0.5 degrees by 0.5 degrees latitude-longitude grid. The gridding uses a hierarchical scheme based on spherical kernel estimators. As part of the gridding procedure, the geostationary data are corrected for limb effects using a simple empirical correction to the radiances, from which the corrected temperatures are computed. This is in addition to the application of satellite zenith angle weighting to downweight limb pixels in preference to nearer-nadir pixels. The polar orbiter data are windowed on the target time with temporal weighting to account for the noncontemporaneous nature of the data. Large regions of missing data are interpolated from adjacent processed images using a form of motion compensated interpolation based on the estimation of motion vectors using an hierarchical block matching scheme. Examples are shown of the various stages in the process. Also shown are examples of the usefulness of this type of data in GCM validation.

Global snow mass measurements and the effect of stratigraphic detail on inversion of microwave brightness temperatures

Snow provides large seasonal storage of freshwater, and information about the distribution of snow mass as Snow Water Equivalent (SWE) is important for hydrological planning and detecting climate change impacts. Large regional disagreements remain between estimates from reanalyses, remote sensing and modelling. Assimilating passive microwave information improves SWE estimates in many regions but the assimilation must account for how microwave scattering depends on snow stratigraphy. Physical snow models can estimate snow stratigraphy, but users must consider the computational expense of model complexity versus acceptable errors. Using data from the National Aeronautics and Space Administration Cold Land Processes Experiment (NASA CLPX) and the Helsinki University of Technology (HUT) microwave emission model of layered snowpacks, it is shown that simulations of the brightness temperature difference between 19 GHz and 37 GHz vertically polarised microwaves are consistent with Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and Special Sensor Microwave Imager (SSM/I) retrievals once known stratigraphic information is used. Simulated brightness temperature differences for an individual snow profile depend on the provided stratigraphic detail. Relative to a profile defined at the 10 cm resolution of density and temperature measurements, the error introduced by simplification to a single layer of average properties increases approximately linearly with snow mass. If this brightness temperature error is converted into SWE using a traditional retrieval method then it is equivalent to ±13 mm SWE (7% of total) at a depth of 100 cm. This error is reduced to ±5.6 mm SWE (3 % of total) for a two-layer model.

Ionospheric measurements of relative coronal brightness during the total solar eclipses of 11 August, 1999 and 9 July, 1945

Swept-frequency (1-10 MHz) ionosonde measurements were made at Helston, Cornwall (50 degrees 06'N, 5 degrees 18'W) during the total solar eclipse on August 11, 1999. Soundings were made every three minutes. We present a method for estimating the percentage of the ionising solar radiation which remains unobscured at any time during the eclipse by comparing the variation of the ionospheric E-layer with the behaviour of the layer during a control day. Application to the ionosonde date for II August, 1999, shows that the flux of solar ionising radiation fell to a minimum of 25 +/- 2% of the value before and after the eclipse. For comparison, the same technique was also applied to measurements made during the total solar eclipse of 9 July, 1945, at Sormjole (63 degrees 68'N, 20 degrees 20'E) and yielded a corresponding minimum of 16 +/- 2%. Therefore the method can detect variations in the fraction of solar emissions that originate from the unobscured corona and chromosphere. We discuss the differences between these two eclipses in terms of the nature of the eclipse, short-term fluctuations, the sunspot cycle and the recently-discovered long-term change in the coronal magnetic field.

A Morphological View of the Sodium 4,4 `-Distyrylbiphenyl Sulfonate Fluorescent Brightness Distribution on Regenerated Cellulose Fibers

Evidence of the sorption of the whitening agent sodium 4,4`-distyrylbiphenyl sulfonate in the presence of the anionic surfactant sodium dodecylsulfate or the cationic surfactant dodecyl trimethyl ammonium chloride on regenerated cellulose fibers is given by several microscopy techniques. Scanning electron microscopy provided images of the cylindrical fibers with dimensions of 3.5 cm (length) and 13.3 mu m (thickness), with empty cores of 1 mu m diameter and a smooth surface. Atomic force microscopy showed a fiber surface with disoriented nanometric domains using both tapping-mode height and phase image modes. Atomic force microscopy also showed that the whitening agent and surfactant molecules were sorbed onto the fiber surface, in agreement with the adsolubilization sorption model. Transmission electron microscopy showed fibers with nanometric parallel cylinders, surrounded by holes where the fluorescent whitening molecules accumulated. On the basis of these techniques, we conclude that the sorption process occurs preferentially on the fiber surface in contact with the water solution, and under saturated conditions, the whitening agent penetrates into the pores and are simultaneously sorbed on the pore walls bulk, forming molecular aggregates. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 2321-2327, 2010

2060 Chiron back to a minimum of brightness

The results of photometric observations of comet/steroid 2060 Chiron at the Observatorio do Pico dos Dias (Brazil - OPD) and the Observatoire de Haute-Provence (France - OHP) during 1994 and 1995 are presented. The analysis of the data shows a decrease of 2060. Chiron brightness from its peak values of 1988-1991. The absolute magnitude, H-V, varies from a maximum of 6.6 in February 1994 up to a minimum of 6.8 in June 1995. Therefore 2060 Chiron is back to a minimum of activity close to that of 1983-1985. The slope parameter G is found to be G = 0.71 +/- 0.15. It is suggested that the H-G magnitude system, generally adopted to present 2060 Chiron brightness, is not the most appropriate due to the cometary activity of this object. Copyright (C) 1996 Elsevier B.V. Ltd.