Microfluidic generation of networked droplet collections and lipid membrane constructs

We report on microfluidic strategies to generate several multi-compartment membrane-based structures, including droplet interface bilayer networks and multi-compartment vesicles. These developments allow the current status quo— where microdroplets are used as isolated vessels— to be changed. By linking droplets together with lipid membranes, higher order systems can be generated, with particular ramifications for bottom-up synthetic biology and for functional droplet-based microreactors and biodevices

Effects of Humidity on the Electro-Optical-Thermal Characteristics of High-Power LEDs

LEDs are subjected to environments with high moisture in many applications. In this paper, the experiments reveal photometric and colorimetric degradation at high humidity. Corresponding spectral power analysis and parameter extraction indicate that the flip-chip bonded LED samples show accelerated chip failure compared to the conventionally bonded samples. The chip-related failure induces greater heat accumulation, which correlates with the increase in heating power observed in the package. However, the temperature rise and thermal resistance for the flip-chip bonded LEDs do not increase substantially as compared to the conventionally bonded LEDs. This is because the junction temperature can be reduced with a flip-chip die-bonding configuration where the heat generated in the LED chip is dissipated effectively onto the AlN substrate, thereby reducing the increase in temperature rise and thermal resistance. The experimental results are supported by evaluation of the derivative structure functions. In addition, as the thermal resistance of the LED package varies with different humidity levels, there is a need to specify the conditions of humidity in data sheets as LED manufacturers routinely specify a universal thermal resistance value under a fixed operating condition

Analysis of photon-atom entanglement generated by Faraday rotation in a cavity

Faraday rotation based on AC Stark shifts is a mechanism that can entangle the polarization variables of photons and atoms. We analyze the structure of such entanglement by using the Schmidt decomposition method. The time-dependence of entanglement entropy and the effective Schmidt number are derived for Gaussian amplitudes. In particular we show how the entanglement is controlled by the initial fluctuations of atoms and photons.Comment: 6 pages, 3 figure

Chinese Adolescents’ Meaning-Focused Coping With Prolonged Parent-Child Separation

postprin

Using an iconic modelling tool to support the learning of genetics concepts

Genetics is a difficult topic as it involves abstract concepts, which are not directly observable. Studies on using simulations to support the learning of genetics have largely been confined to the use of quantitative simulations to replace experimentation. This study describes the use of a new type of simulation built using an iconic modelling tool, WorldMaker (WM), that can (1) support multiple iconic visualisations of the simulated phenomena, (2) support the visualisation of instantaneous local changes as a simulation is executed as well as the time variation in global changes as the simulation unfolds, and (3) allow the user to examine and modify all of the rules governing the behaviour of the simulations. This study reveals that students' exploration of genetic phenomena using simulations built in WM elicits theorising from them that exposes their prior misconceptions as well as stimulates further exploration and co-construction of genetic understanding that is closer to the scientific view. It helps students to understand operationally difficult concepts like genotypes and phenotypes, as well as to understand genetic ratio as a deterministic value derived from inheritance events that are probabilistic and random in nature.published_or_final_versio

Explorations in promoting conceptual change in electrical concepts via ontological category shift

Chi (1992, 1993) Chi et al. (1994) suggests that many of the difficulties encountered by students in learning Physics concepts arise because they attribute the ontology of material substances to these concepts. These concepts are actually a special type of process - 'Constraint-Based Interactions' (CBI). Slotta and Chi (1996) reported on a study where a group of students explicitly trained in the CBI ontology showed significant gains over a control group in problem solving performance in eight simple electric circuit problems. This paper reports on a series of four studies which explore the usefulness of the ontological categorization framework in investigating students' alternative conceptions of electric circuits and in developing a teaching strategy for promoting conceptual change in the learning of basic electric circuitry concepts.postprin

Model for resonant photon creation in a cavity with time dependent conductivity

In an electromagnetic cavity, photons can be created from the vacuum state by changing the cavity's properties with time. Using a simple model based on a massless scalar field, we analyze resonant photon creation induced by the time-dependent conductivity of a thin semiconductor film contained in the cavity. This time dependence may be achieved by irradiating periodically the film with short laser pulses. This setup offers several experimental advantages over the case of moving mirrors.Comment: 9 pages, 1 figure. Minor changes. Version to appear in Phys. Rev.