Recombinant adenovirus vectors and transfection agents comprising cationic lipids are widely used as gene delivery vehicles for functional expression in cultured cells. Consequently, these tools are utilized to investigate the effects of functional over-expression of proteins on insulin mediated events. However, we have previously reported that cationic lipid reagents cause a state of insulin unresponsiveness in cell cultures. In addition, we have found that cultured cells often do not respond to insulin stimulation following adenovirus treatment. Infection with adenovirus compromises vital functions of the host cell leading to the activation of protein kinases central to insulin signalling, such as protein kinase B/Akt. Therefore, we investigated the effect of adenovirus infection on insulin unresponsiveness by means of Akt activation in cultured cells. Moreover, we investigated the use of baculovirus as a heterologous viral gene delivery vehicle to circumvent these phenomena. Since the finding that baculovirus can efficiently transduce mammalian cells, the applications of this viral system in gene delivery has greatly expanded and one advantage is the virtual absence of cytotoxicity in mammalian cells. We show that infection of human neuroblastoma SHSY-5Y and liver C3A cells with recombinant adenovirus results in the activation of Akt in a dose dependent manner. In addition, this activation makes treated cells unresponsive to insulin stimulation as determined by an apparent lack of differential phosphorylation of Akt on serine-473. Our data further indicate that the use of recombinant baculovirus does not increase the phosphorylation of Akt in SHSY-5Y and C3A cells. Moreover, following infection with baculovirus, SHSY-5Y and C3A cells respond to insulin by means of phosphorylation of Akt on serine-473 in the same manner as uninfected cells. Widely-used adenovirus vectors for gene delivery cause a state of insulin unresponsiveness in human SHSY-5Y and C3A cells in culture due to the activation of central protein kinases of the insulin signalling pathway. This phenomenon can be avoided when studying insulin signalling by using recombinant baculovirus as a heterologous viral expression system. In addition, our data may contribute to an understanding of the molecular mechanisms underlying baculovirus infection of human cells.

This paper analyses leakage current compensation techniques for low-power, bandgap temperature sensors. Experiments are conducted for circuits that compensate for collector-substrate, collector-base, body-drain and source-body leakage currents in a Brokaw bandgap sensor. The sensors are characterised and their failure modes are analysed at temperatures from 60 to \(230^{\,\circ }\hbox {C}\). It is found that the most appropriate compensation circuit depends on the accuracy requirements of the application and on whether a stable reference voltage is required by other parts of the circuit. Experiments show that the power consumption is dominated by leakage current at high temperatures. One type of sensor was seen to consume 260 nW at \(60 ^{\,\circ }\hbox {C}\), \(2.1\, \upmu \hbox {W}\) at \(200^{\,\circ }\hbox {C}\) and \(14\, \upmu \hbox {W}\) at \(230^{\,\circ }\hbox {C}\). This work is motivated by the need to accurately monitor the temperature of power semiconductors in order to predict emerging faults in power semiconductor modules, a task for which cheap, single-chip, low-power, high-temperature, wireless bandgap temperature sensors are appropriate.

This paper presents a circuit for realising a fuse-programmable capacitor on-chip. The trimming mechanism is implemented using integrated circuit fuses which can be blown in order to lower the resulting equivalent capacitance. However, for integrated circuits, the non-zero fuse resistance for active fuses and finite fuse resistance for blown fuses limit the Q factor of the resulting capacitor. In this work, we present a method on how to arrange the fuses in order to achieve maximal worst-case Q factor for the given circuit topology given the process parameters and requirements on capacitance. We also analyse and discuss the accuracy and limitations of the topology with regard to fuse resistance and parasitic elements such as bond pads.

This paper presents electromagnetic simulations of a wireless power transfer system suitable for a monitoring system for detection of solder fatigue in power semiconductor modules. Power is provided wirelessly from a printed spiral coil on a printed circuit board to a silicon chip with an on-chip coil. We use and adapt a known gradient-ascent-based optimization algorithm to obtain suitable coil geometries. For a frequency of 433 MHz, the simulations show an efficiency of -33.9 dB which we conclude is sufficient for the proposed monitoring system.

Computational intelligence is often used in smart environment applications in order to determine a user's context. Many computational intelligence algorithms are complex and resource-consuming which can be problematic for implementation devices such as FPGA:s, ASIC:s and low-level microcontrollers. These types of devices are, however, highly useful in pervasive and mobile computing due to their small size, energy-efficiency and ability to provide fast real-time responses. In this paper, we propose a classifier, CORPSE, specifically targeted for implementation in FPGA:s, ASIC:s or low-level microcontrollers. CORPSE has a small memory footprint, is computationally inexpensive, and is suitable for parallel processing. The classifier was evaluated on eight different datasets of various types. Our results show that CORPSE, despite its simplistic design, has comparable performance to some common machine learning algorithms. This makes the classifier a viable choice for use in pervasive systems that have limited resources, requires energy-efficiency, or have the need for fast real-time responses.

This paper presents a theory for the power transfer efficiency of printed circuit board coils to integrated circuit coils, with focus on load-dependence for low-power single-chip systems. The theory is verified with electromagnetic simulations modelled on a 350 nm CMOS process which in turn are verified by measurements on manufactured integrated circuits. The power transfer efficiency is evaluated by on-chip rectification of a 151 MHz signal transmitted by a spiral coil on a printed circuit board at 10 mm of separation to an on-chip coil. Such an approach avoids the influence of off-chip parasitic elements such as bond wires, which would reduce the accuracy of the evaluation. It is found that there is a lower limit for the load below which reducing the power consumption of on-chip circuits yield no increase in voltage generated at the load. For the examined process technology, this limit appears to lie around 56 k $$\Omega$$Ω . The paper is focused on the analysis and verification of the theory behind this limit. We relate the results presented in this work to the application of wireless single-chip temperature monitoring of power semiconductors and conclude that such a system would be compatible with this limit.