A study of lithographic ink and water interactions

Achieving and maintaining the correct ink/water balance is crucial for acceptable print quality; this involves factors affecting the emulsification of water and ink. This process was investigated with two designed model ink varnishes (one being 'hydrophilic' relative to the other 'hydrophobic' varnish) and two commercial varnishes. The Surland test, widely used to characterise ink/water balance, showed differences in water uptake between inks and corresponding varnishes; however it did not distinguish between the 'hydrophilic' and 'hydrophobic' systems. Thus, the rheology of the systems are considered together with implications to the lithographic process. Rheological studies of creep and flow showed that the hydrophilic and hydrophobic systems behaved differently in the presence of water. The rheology of the ink varnish plays a major role in emulsification and the nature of processes at the interface affecting droplet fragmentation, droplet coalescence and time-dependency. Slippage occurred in the hydrophobic systems to a greater extent compared with the hydrophilic systems increasing with water concentrations from 0 to 25% water. Droplet size distributions of the emulsion depend on temperature and agitation speeds. As emulsions approached dynamic equilibria, mean droplet diameters in the hydrophobic varnish at 70°C and 40°C were found to be ca. 2S and 12 I'm respectively; corresponding mean droplet diameten in the hydrophilic varnish were ca. 20 I'm and 5 I'm. Increase of interfacial tension for both varnishes (ca. 6 mNm-l) between 40°C and 70°C, may not be significant to droplet breakdown. A reduction in viscosity i.e. from 100 to 5 Pas in the hydrophobic varnish and from 300 to 5 Pas for the hydrophilic varnish was the determining factor. Droplet size depends on temperature: e.g. temperature increases led to larger droplets. Viscosity ratios of the continuous and disperse phases account for these effects. Investigating the time-dependency of the system showed that allowing 'rest periods' between episodes of mixing altered the rate and nature of emulsification. Thus using a modified varnish, rest periods of 1 and 3 minutes produced mean droplet diameters in the range of 1.5-1.8 um whereas rest period of 5 minutes produced diameters of 2.3-2.4 I'm indicating that thixotropic recovery which occurs up to 3 minutes, restores the rate of droplet breakdown; whereas, after 5 minutes, coalescence is dominant. Extending the 'rest period' allows time for drainage of a film of continuous phase between two colliding droplets. These time-dependent effects varied with different varnish modifications. The effect of IP A on emulsification was also time-dependent. During 3 minutes of stirring at 900 rpm, the number of droplets below 2 I'm was greater in an emulsion containing IP A than in one containing water only; the situation was reversed after 4 minutes of stirring where the number of droplets below 2 um was lower. A decrease in interfacial viscosity at the varnish/water interface is considered; such a decrease may reduce the effective shear stress at the interface and thus the extent of droplet breakdown

Genetic Assimilation and Canalisation in the Baldwin Effect

The Baldwin Effect indicates that individually learned behaviours acquired during an organism’s lifetime can influence the evolutionary path taken by a population, without any direct Lamarckian transfer of traits from phenotype to genotype. Several computational studies modelling this effect have included complications that restrict its applicability. Here we present a simplified model that is used to reveal the essential mechanisms and highlight several conceptual issues that have not been clearly defined in prior literature. In particular, we suggest that canalisation and genetic assimilation, often conflated in previous studies, are separate concepts and the former is actually not required for non-heritable phenotypic variation to guide genetic variation. Additionally, learning, often considered to be essential for the Baldwin Effect, can be replaced with a more general phenotypic plasticity model. These simplifications potentially permit the Baldwin Effect to operate in much more general circumstances

Evaluating spring wheat cultivars for drought tolerance through yield and physiological parameters at booting and anthesis

Progress in wheat yields under drought conditions is rather a difficult task to achieve. The experiment was conducted in factorial design with 16 spring wheat cultivars grown under two irrigation regimes, non-stress and water-stress imposed at boot and anthesis growth stages. Water-stress significantly influenced the physiological and yield traits in both the growth stages, yet the reductions in most traits were pronounced at anthesis than at boot. Stomatal conductance, relative water content, leaf area (LA), seeds/spike, 1000-grain weight and grain yield/plant were the best drought tolerant indicators. On the basis of physiological and yield traits, the cultivars Moomal, Bhitai, TD-1, and Abadgar proved to be the best performing in water-stress conditions. Stomatal conductance, RWC% and LA were significantly and positively correlated with grain yield/plant. These results suggest that the stomatal conductance, relative water content and leaf area are the most important traits that should be considered while developing drought tolerant wheat genotypes.Keywords: Water stress, boot and anthesis, yield and physiological traits, wheat genotype

The Origin of Radio Scintillation In the Local Interstellar Medium

We study three quasar radio sources (B1257-326, B1519-273, and J1819+385) that show large amplitude intraday and annual scintillation variability produced by the Earth's motion relative to turbulent-scattering screens located within a few parsecs of the Sun. We find that the lines of sight to these sources pass through the edges of partially ionized warm interstellar clouds where two or more clouds may interact. From the gas flow vectors of these clouds, we find that the relative radial and transverse velocities of these clouds are large and could generate the turbulence that is responsible for the observed scintillation. For all three sight lines the flow velocities of nearby warm local interstellar clouds are consistent with the fits to the transverse flows of the radio scintillation signals.Comment: 16 pages, 5 figures; Accepted for publication in Ap

Landscape statistics of the p-spin Ising model

The statistical properties of the local optima (metastable states) of the infinite range Ising spin glass with p-spin interactions in the presence of an external magnetic field h are investigated analytically. The average number of optima as well as the typical overlap between pairs of identical optima are calculated for general p. Similarly to the thermodynamic order parameter, for p>2 and small h the typical overlap q_t is a discontinuous function of the energy. The size of the jump in q_t increases with p and decreases with h, vanishing at finite values of the magnetic field.Comment: 12 pages,te

The cell cycle regulator p27kip1 contributes to growth and differentiation of osteoblasts

The cyclin-dependent kinase (cdk) inhibitors are key regulators of cell cycle progression. p27 and p21 are members of the Cip/Kip family of cdk inhibitors and regulate cell growth by inactivating cell cycle stage-specific CDK-cyclin complexes. Because down-regulation of osteoprogenitor proliferation is a critical step for osteoblast differentiation, we investigated expression of p27 and p21 during development of the osteoblast phenotype in rat calvarial osteoblasts and in proliferating and growth-inhibited osteosarcoma ROS 17/2.8 cells. Expression of these proteins indicates that p21, which predominates in the growth period, is related to proliferation control. p27 levels are maximal postproliferatively, suggesting a role in the transition from cell proliferation to osteoblast differentiation. We directly examined the role of p27 during differentiation of osteoprogenitor cells derived from the bone marrow (BM) of p27-/- mice. BM cells from p27 null mice exhibited increased proliferative activity compared with BM cells from wild-type mice and formed an increased number and larger size of osteoblastic colonies, which further differentiated to the mineralization stage. Although p27-/- adherent marrow cells proliferate faster, they retain competency for differentiation, which may result, in part, from observed higher p21 levels compared with wild type. Histological studies of p27-/- bones also showed an increased cellularity in the marrow cavity compared with the p27+/+. The increased proliferation in bone does not lead to tumorigenesis, in contrast to observed adenomas in the null mice. Taken together, these findings indicate that p27 plays a key role in regulating osteoblast differentiation by controlling proliferation-related events in bone cells

How to return to subjectivity? Natorp, Husserl, and Lacan on the limits of reflection

This article discusses the recent call within contemporary phenomenology to return to subjectivity in response to certain limitations of naturalistic explanations of the mind. The meaning and feasibility of this call is elaborated by connecting it to a classical issue within the phenomenological tradition concerning the possibility of investigating the first-person perspective through reflection. We will discuss how this methodological question is respectively treated and reconfigured in the works of Natorp, Husserl, and Lacan. Finally, we will lay out some possible consequences of such a cross-reading for the conception of subjectivity and the concomitant effort to account for this dimension of first-person experience in response and in addition to its omission within the standard third-person perspective of psychological research