New color-shifting security devices

This study investigated chromatic induction from inhomogeneous background patterns. Previous work showed that a background pattern detected by only S cones induced strong color shifts in a nearby test area (Monnier & Shevell, 2003). In that work, the S-cone patterns were composed with constant L- and M-cone stimulation over the entire background; in terms of L and M cones, therefore, the background was uniform. S-cone stimulation was varied over space to produce S-cone-isolated background patterns. These S-cone patterns, however, established spatial structure (the pattern) at both the receptoral level (S-cone stimulation) and the postreceptoral level (S/(L+M)). Here, these two levels of pattern representation were unconfounded to determine whether color shifts induced by S-cone patterns were due to spatial structure within an S-cone-specific neural pathway versus a pathway that combines responses from S cones and other cone types (e.g. S/(L+M)). The results showed that the induced color shifts were mediated by signals within a pathway that combines responses from multiple cone types. These results are consistent with a +s/-s spatially antagonistic neural receptive field, which is found in some neurons in V1 and V2.

Large format ink jet prints are widely used for graphic arts, displays, posters, and signage applications. In order to protect display media and to extend the life of image when printed with aqueous based inks, laminating of the printed image is usually employed in the inkjet printing applications. However, lamination may impact image quality and color shift, as well as the color fading rates. The purpose of this experimental study is to examine the effects of lamination on image quality and light stability of display media. In this study, a digital four-color test chart was designed and printed onto commercial available display media (adhesive vinyl and display film) by using dye and pigment ink systems. Printed display media were laminated with pressure-sensitive laminating films. Print quality of display media was evaluated in terms of optical density and color gamut. A Q-Sun Xenon test chamber was employed to examine the light fastness properties of printed display media. The color fading rates of these prints were examined according to color difference (ΔE*ab) in L*a*b* color space. The study results provide us with both visual and numerical comparisons among various media/ink/over-laminate combinations.

This paper reports on the development of liquid crystal for the electrochemical study of photo-induced electron transfer. This study covers the following studies: the description of the laminar liquid crystals (LLCs) system by using CPZ.HCl material, examining the lyotropic liquid crystal system of CPZ.HCl compound and its application in the photogalvanic cell. Chlorpromazine hydrochloride (CPZ.HCl) was first shown to form a lyotropic liquid crystal (LLC) when the concentrations reached > 10 M in an aqueous solution. This self-assembly was revealed through the birefringence observed through cross-polarisers and the characteristic X-ray scattering. The electrochemistry of the CPZ.HCl- LLC system was probed through the use of cyclic voltammetry using different micro-electrode materials, diameters and CPZ.HCl concentrations. Following this, this system was fabricated into a photogalvanic cell that produced a power conversion efficiency (PCE) of 0.58 %.

Background: In accordance with the objectives envisaged by the Vision 2020 WHO global initiative, this study was designed to reveal the causes of low vision (LV), patient preference for and acceptance of specific types of low vision devices. The study was performed between January, 2006 and December, 2006 at the Low Vision Clinic in Lumbini Eye Institute (LEI). Materials and Methods: A descriptive clinical study of patients with low vision was performed. All patients were examined by an Ophthalmologist and an Optometrist. Un-corrected visual acuity (VA), best-corrected visual acuity (BCVA), visual loss based on anatomical sites, low vision assessment was performed and patient preference for a specific low vision device was observed and documented. Standard National Low Vision Assessment Form was used. Results: A total of 166 new Nepali patients were included in the study out of whom 70% were male. Of these patients, lens related causes like aphakia, pseudophakia was the main cause of low vision in 35.55% patients, followed by refractive errors / amblyopia accounted for 19.23%, retinitis pigmentosa for 10.84%, whole globe abnormalities 10.25%, corneal pathology accounted for 7.24%, retinal disease (different types of maculopathies, retinal scars, retinal hemorrhages, vein occlusion, etc.) in 6.64%, and other causes (albinism, nystagmus, different syndromes, etc.) in 10.25%. In low vision assessment, 6.02 % not needed any device (sufficient near vision enough to conduct his or her near task without any type of devices / glasses) as per the guidelines set up by National Low Vision Programme), distance glasses gave enough improvement for 19.27%, spectacle magnifier was preferred by 51.80%, other magnifiers (hand/stand/dome) was preferred by 12.65%, and monocular handheld telescope was preferred by 20.48% for distance. The above includes certain patients requiring assistance with both near and distance vision who opted for multiple LV devices (i.e., for near and distance vision separately) instead of LV devices with multiple functionality. In non-optical Low-vision devices, 25 % preferred reading lamp, 10 % preferred reading stand, 12% preferred black felt tip pen, 6 % preferred sunglasses, 7 % preferred peaked cap, 4 % preferred typoscope, and 3 % preferred LV note book. Conclusion: Lens related causes and refractive errors/amblyopia seem to be two of the most important causes of low vision and should not be overlooked. In addition, low vision devices with a usage similar to that of spectacles were preferred by patients for near and telescope for distance.

We have computed the convection potential drop across the polar cap from data obtained on high‐inclination low‐altitude satellites (AE‐C, AE‐D, S3‐3) and correlated these potential measurements with various combinations of parameters measured simultaneously in the upstream solar wind. These combinations of solar wind parameters consist of predictions based on magnetic merging theory and suggestions based on earlier empirical work. We find that the bulk of the potential drop, and its variation with interplanetary magnetic field (IMF) parameters, are successfully predicted by merging theory (to the accuracy with which they can presently be measured), but that a significant ‘background’ potential drop (∼35 kV) does not depend on IMF parameters and may thus be attributed to an unknown process other than merging. Our results indicate that small values of the IMF are amplified by a factor of 5–10 at the dayside magnetopause as a combined effect of bow shock compression and the Zwan‐Wolf depletion layer effect; correlations between IMF parameters and the polar cap potential drop are dramatically improved when this amplification is taken into account. The potential drop is better correlated with IMF parameters than with geomagnetic activity indices, presumably because the latter are affected by nonlinear reponses of the magnetosphere to the polar cap input.

In the electro-hydrodynamic systems of nematic liquid crystals with free and rigid boundaries and a small aspect ratio, the pattern evolution process on applying the stepwise ac voltage was studied. The convective rolls appeared at the both lateral sides of the system, and evolved toward the center. It was found that the pattern is selected through the phase jump. The pattern in the free lateral boundary cell had more flexibility than in the rigid lateral boundary cell. The interactions between the two subsystems separated by free lateral boundary and the selection of the pattern were studied. It was found that the evolution and the selection of the pattern in a subsystem were affected by those in the other subsystem through the free boundary.

The International Workshop on the Physics of Soft Matter Complexes was held from 29 November to 2 December 2004 at Tokyo Metropolitan University, Tokyo, Japan. The aim of the workshop was to discuss the current topics of composite systems of surfactants, polymers, colloids, liquid crystals and biological materials. Special attention was focused on the features that are realized due to the combination of those materials. Distinguished invited speakers from Japan and the rest of the world, and many other workers in the field, participated in this workshop. The topics covered were colloids, polymers, surfactants, biomaterials such as proteins and DNA, rheology, and their composite systems. We, the organizing committee of this workshop, wished not only to show the activity of Japanese workers in this field but also wanted to exchange and discuss ideas on the theme with workers from other countries. In addition, although as physicists we tend to study simple systems, as the theme of our workshop we focused on complex or composite systems. We hope that readers will see that the many excellent papers in this special issue of Journal of Physics: Condensed Matter show that the aim of the workshop was achieved. Lastly, we acknowledge that the workshop was held as part of the project for the promotion of international conferences by the Japan Society for the Promotion of Science.

The process of liquid–liquid crystalline phase separation (LLCPS) in filamentous colloids is at the very core of multiple biological, physical and technological processes of broad significance. However, the complete theoretical understanding of the process is still missing. LLCPS involves the nucleation, growth and up-concentration of anisotropic droplets from a continuous isotropic phase, until a state of equilibrium is reached. Herein, by combining the thermodynamic extremum principle with the Onsager theory, we describe the nucleation and growth of liquid crystalline droplets, and the evolution of their size and concentration during phase separation, eventually leading to a multitude of order–order phase transitions. Furthermore, a decreasing pitch behaviour can be predicted using this combined theory during tactoid growth, already observed experimentally but not yet explained by present theories. The results of this study are compared with the experimental data of cholesteric pitch, observed in three different systems of biological chiral liquid crystals. These findings give an important framework for predicting the formation, growth and phase behaviour of biological filamentous colloids undergoing LLCPS, advancing our understanding of liquid–liquid phase separation and self-assembly mechanisms in biological systems, and provide a valuable rationale for developing nanomaterials and applications in nanotechnology.

Phase transiion behaviour of binary systems of discotic liquid crystals

Smectic blue phases (BP(sm)) are original physical systems of thermotropic liquid crystals, displaying a double geometrical frustration: the extension of chirality in the three spatial dimensions, such as classical blue phases, and the competition between smectic order and helical twist, such as twist grain boundary (TGB) phases. We report experimental evidence of the influence of the underlying TGB((A) or (C)) phase on the BP(sm) structure.

Tapping mode atomic force microscopy (AFM) provides phase images in addition to height and amplitude images. Although the behavior of tapping mode AFM has been investigated using mathematical modeling, comprehensive understanding of the behavior of tapping mode AFM still poses a significant challenge to the AFM community, involving issues such as the correct interpretation of the phase images. In this paper, the cantilever's dynamic behavior in tapping mode AFM is studied through a three dimensional finite element method. The cantilever's dynamic displacement responses are firstly obtained via simulation under different tip-sample separations, and for different tip-sample interaction forces, such as elastic force, adhesion force, viscosity force, and the van der Waals force, which correspond to the cantilever's action upon various different representative computer-generated test samples. Simulated results show that the dynamic cantilever displacement response can be divided into three zones: a free vibration zone, a transition zone, and a contact vibration zone. Phase trajectory, phase shift, transition time, pseudo stable amplitude, and frequency changes are then analyzed from the dynamic displacement responses that are obtained. Finally, experiments are carried out on a real AFM system to support the findings of the simulations.

There has been increasing recognition of the phenomenon of growth rate dispersion in the analysis and characterization of the crystal growth process. The concept originated from early work on the crystallization of sugar (White and Wright, 1971). Since then, several researchers have shown that for many crystallization systems—when a group of crystals, all of which have the same initial size, has been grown under globally identical external conditions of supersaturation, temperature, and hydrodynamics in a batch crystallizer under conditions of negligible nucleation—a stochastic variation in crystal growth rates exists, resulting in a broadening of the product crystal size distribution.

Cyber security is not only a hot topic debated intensely among business managers, but also a growing concern that enforces unplanned and often undesirable changes. Too tight security measures usually result in a spike in customer complaint volumes; too slack cause a lot of grey hair, especially after a breach. Continuously accelerating growth in number of IT applications, proliferation of various types of devices, software versions, channels and endpoints are significantly increasing the surface area of potential attacks. For professionals with strong links with the world of finance and security, it comes as no surprise that the old approaches are rapidly becoming obsolete. In many cases they cannot handle new challenges, not to mention elaborate and constantly evolving sociological theft strategies. New approaches are desperately sought. The hunt for the holy grail in a cyber security area has been on for quite some time now — apparently without a clear conclusion, as cybercrime is on the rise, regardless of the industry or geographical region. Data leaks and account takeovers have become daily news stories that many people pay attention to. This is why decision makers are exploring different approaches to security by venturing into new territories that were previously not purely classified as directly connected with security issues. Yet, if we want to ensure our clients’ finances, data and interests are appropriately protected, surely all options should be considered? This paper aims to shift the way managers view security in their institutions by highlighting alternative ways of approaching the subject. By incorporating into security interconnected and interdependent layers of verification mechanisms, higher fraud/takeover detection rates can be achieved without affecting usability. Readers will gain complex insights as to how these layers behave and how they operate within the financial institutions.

The luminescence of alkaline earth sulfates and silicates activated by anions, has been observed. The activating anions were , , , , , , , , , , , S2−, and . The products showed fluorescent emissions varying in color from blue to red and in visible intensity from very faint to strong. The samples showing the strongest emission are: and , both emitting in the blue. Evidence is presented to show that these phosphors are truly activated by the ion, and not simply dilute samples of the tungstates. It is proposed that activation by anions can be divided into two classes: intraionic, where the emission occurs within the impurity anion; and interionic, where more complex interactions occur. The latter class shows strong shifts in emission color as the host crystal is changed; the intraionic group, including tungstate and vanadate, generally show stronger emission than the others.

The applications of elastic and quasielastic light scattering techniques to polymers in dilute solution, thermotropic liquid crystals and biological membrane vesicles are presented. It is focused on how we extract specific structural features or dynamic processes of these condensed medium samples through the light scattering methods. The paper reviews the light scattering studies that were carried out at the author's laboratory in Wisconsin from 1973 until 1980.