Self-assembled polymeric solid films with temperature-induced large and reversible photonic-bandgap switching

In aqueous solutions the response of polymers and biological matter to external conditions, such as temperature and pH, is typically based on the hydrophobic/hydrophilic balance and its effects on the polymer conformation. In the solid state, related concepts using competing interactions could allow novel functions. In this work we demonstrate that polymeric self-assembly, reversibility of hydrogen bonding, and polymer-additive phase behaviour allow temperature response in the solid state with large and reversible switching of an optical bandgap. A complex of polystyrene-block-poly(4-vinylpyridinium methanesulphonate) and 3-n-pentadecylphenol leads to the supramolecular comb-shaped architecture with a particularly long lamellar period. The sample is green at room temperature, as an incomplete photonic bandgap due to a dielectric reflector is formed. On heating, hydrogen bonds are broken and 3-n-pentadecylphenol additionally becomes soluble in polystyrene, leading to a sharp and reversible transition at approximately 125 degrees C to uncoloured material due to collapse of the long period. This encourages further developments, for example, for functional coatings or sensors in the solid state.     

Microchip atmospheric pressure chemical ionization source for mass spectrometry

A novel microchip heated nebulizer for atmospheric pressure chemical ionization mass spectrometry is presented. Anisotropic wet etching is used to fabricate the flow channels, inlet, and nozzle on a silicon wafer. An integrated heater of aluminum is sputtered on a glass wafer. The two wafers are jointed by anodic bonding, creating a two-dimensional version of an APCI source with a sample channel in the middle and gas channels symmetrically on both sides. The ionization is initiated with an external corona-discharge needle positioned 2 mm in front of the microchip heated nebulizer. The microchip APCI source provides flow rates down to 50 nL/min, stable long-term analysis with chip lifetime of weeks, good quantitative repeatability (RSD < 10%) and linearity (r(2) > 0.995) with linear dynamic rage of at least 4 orders of magnitude, and cost-efficient manufacturing. The limit of detection (LOD) for acridine measured with microchip APCI at flow rate of 6.2 muL/min was 5 nM, corresponding to a mass flow of 0.52 fmol/s. The LOD with commercial macro-APCI at a flow rate of 1 mL/min for acridine was the same, 5 nM, corresponding to a significantly worse mass flow sensitivity (83 fmol/s) than measured with microchip APCI. The advantages of microchip APCI makes it a very attractive new microfluidic detector.     

Time-out in user interface: the case of mobile text input

In many user interfaces with restricted input capabilities, a time-out is used to automatically change the user interface (UI) from one mode to another. In this paper, we study the learning of time-outs and the effect of feedback on it in the case of mobile phone text entry. The effects of three different feedback schemes (auditory/visual/no feedback) on the learning of two different time-out lengths were compared. We measured the response time (RT) from the time-out occurrence to the time of the users action. Error rates and the development of the RTs in different schemes were used as measures of learning. We also studied if the users learned to estimate the time-out lengths, or if they just reacted to the available feedback. There were three main findings. Without feedback, RTs had a great variation. Auditory feedback enabled faster RTs than visual feedback. Finally, we found evidence of short-term learning, but not much of a lasting effect. The possible application of adapting time-out length to user RT is discussed.     

Intercalibration of SUMER and CDS on SOHO. III. SUMER and CDS-GIS. Solar and Heliospheric Observatory

Simultaneous observation of the same solar sources with different instruments is one way to test prelaunch radiometric calibrations and to detect changes in responsivity with time of extreme-ultraviolet instruments in space. Here we present the results of intercalibration of the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrometer (detectors A and B) and the GIS (Grazing Incidence Spectrometer), one of two spectrometers that compose the CDS (Coronal Diagnostic Spectrometer) on the Solar and Heliospheric Observatory (SOHO). The two instruments observed simultaneously radiances of emission lines at or near the center of the solar disk. The emission line chosen for intercomparison was Ne VIII at 770 A. However, such an intercomparison of the SUMER and CDS-GIS measurements means comparing two data sets with large differences in resolution and field of view. The latter difference, especially, introduces differences in the measured intensities caused by the solar variability that is relatively strong in the 770-A line. Using a statistical approach to overcome this problem, we found that the ratio of the GIS to the SUMER average radiances amounted to 2.6 +/- 0.9 before the SOHO's loss of attitude and to 2.1 +/- 0.7 afterward. These findings confirm earlier estimates of the GIS's responsivity being too low, and an update of the GIS calibration is recommended. Despite the large differences in resolution and field of view of the two instruments, the shapes of their normalized and rescaled histograms of the radiances agree well and therefore represent characteristic features of the Ne VIII line.     

Travelling with Linux malware: Is Linux security for real?

Linux, is an Unix-like operating system. Although it is used mainly as a server operating system, it is slowly gaining more acceptance amongst end users. It has integrated security features and has the potential to help users protect themselves against malware. However, as we have seen, even Linux is not immune from such attacks.While the number of Windows worms has been increasing exponentially, to date there have only been a handful of malware programs directed at Linux. But as the number of workstation users running Linux increases, and as home users start to be connected via leased lines to the Internet, the situation may change. One indication of such progress was seen earlier this year, when Ramen was spreading Linux systems.This paper concentrates on current Linux malware, and describes the most typical malware seen on a Linux host.

Worms

The first Linux worm found in the wild, namely ADMworm, was reported by CERT®/CC[1] in 1998. It propagated in a fully automated fashion using a buffer overflow vulnerability in bind Domain Name Service server [1], and as such was very similar to the Internet Worm created by Robert Morris. The Morris worm almost shut down the entire Internet in November 1998. It was a VAX/VMS and SunOS based worm that exploited known vulnerabilities in sendmail’s debugging mode, fingerd and rsh/rexec. Within few hours the worm spread allegedly to more than half of the computers on the Internet at that time.This worm is similar to almost all Linux worms today — it is fully automatic, requires no user innovation and uses known vulnerabilities of the host operating system for its replication.[2]Table 1     

Oil entrainment in vertical refrigerant pipingEntraînement de l''huile dans les tuyauteries frigorifiques verticales

The aim of this study is to investigate the required refrigerant speed, hence minimum refrigeration load, for carrying the lubricating oil up in vertical sections of refrigerant lines. It is assumed that the downward flow of the thin oil layer over the inner surface of the riser due to gravity is to be balanced with the upward flow of the oil film due to the shear force created by the upward flow of the refrigerant vapor. Velocities are converted to refrigeration capacities by considering a saturated cycle between specified condenser and evaporator pressures. General relationships thus developed are enumerated for R134a by preparing minimum capacity tables for copper suction and discharge risers.     

Environment Analysis as a Basis for Designing Multimodal and Multidevice User Interfaces

In this article, we present a practical approach to analyzing mobile usage environments. We propose a framework for analyzing the restrictions that characteristics of different environments pose on the user's capabilities. These restrictions along with current user interfaces form the cost of interaction in a certain environment. Our framework aims to illustrate that cost and what causes it. The framework presents a way to map features of the environment to the effects they cause on the resources of the user and in some cases on the mobile device. This information can be used for guiding the design of adaptive and/or multimodal user interfaces or devices optimized for certain usage environments. An example of using the framework is presented along with some major findings and three examples of applying them in user interface design.     

Prediction of capillary tubes with alternative refrigerants to CFC‐502

A numerical model is presented in this paper, for predicting capillary tube performance using new alternative refrigerants to CFC‐502. The model has been established after the fluid flow conservation equations written for a homogeneous azeotropic refrigerant fluid flow under saturated, sub‐cooled and two‐phase conditions. The study was limited to the following azeotropic mixtures; R‐507, R‐404A, and quaternary mixture (R32/R125/R134a/R143a). Numerical results showed that the proposed model in question fairly simulated our experimental data and fairly predicted the capillary tube behaviour under different conditions. The results also indicated that a system using R‐507 would experience smaller pressure drop across the capillary compared to the other alternatives under question. Copyright © 2001 John Wiley & Sons, Ltd.