Improving practical sensitivity of energy optimized wake-up receivers: proof of concept in 65nm CMOS

We present a high performance low-power digital base-band architecture, specially designed for an energy optimized duty-cycled wake-up receiver scheme. Based on a careful wake-up beacon design, a structured wake-up beacon detection technique leads to an architecture that compensates for the implementation loss of a low-power wake-up receiver front-end at low energy and area costs. Design parameters are selected by energy optimization and the architecture is easily scalable to support various network sizes. Fabricated in 65nm CMOS, the digital base-band consumes 0.9uW (V_DD=0.37V) in sub-threshold operation at 250kbps, with appropriate 97% wake-up beacon detection and 0.04% false alarm probabilities. The circuit is fully functional at a minimum V_DD of 0.23V at f_max=5kHz and 0.018uW power consumption. Based on these results we show that our digital base-band can be used as a companion to compensate for front-end implementation losses resulting from the limited wake-up receiver power budget at a negligible cost. This implies an improvement of the practical sensitivity of the wake-up receiver, compared to what is traditionally reported.Comment: Submitted to IEEE Sensors Journa

The impact of calorie and physical activity labelling on consumer’s emo-sensory perceptions and food choices

Providing labelling information is one of the strategies used to help consumers make healthier choices. However, although the type of information has the potential to assist consumers, it is important to evaluate their sensory and emotional perceptions. Therefore, the objective of this study was to evaluate the effect of different labelling information on consumers' sensory and emotional perceptions and their choices, for three different products (potato chips, juice and yogurt). A total of 480 participants were randomly assigned to one of four information conditions (no information (blind), kilocalorie (kcal) information, physical activity (PA) information [duration of walking required to burn the kcal in the product], kcal + PA information). For each information condition, participants were provided with higher kcal and lower kcal equivalent food pairs and were required to choose one. The participants evaluated their overall liking using a 9-point hedonic scale and answered rate-all-thatapply (RATA) questions related to the sensory and emotional characteristics of the products. The results showed no significant impact of calorie and physical activity labelling on consumers' overall liking for juice and yogurt samples and no impact of PA information for chips. Significant differences in overall liking were found when comparing the blind condition with kcal and kcal + PA information, with lower acceptance of the chips samples when this information was presented. Although providing calorie and physical activity labelling had little impact on consumers' sensory and emotional perceptions, consumers perceived unhealthy attributes and negative emotions, such as fatty and guilty, when information was presented. The present work suggests that, although nutrition labelling may be presented as an important strategy to assist consumers, it is important to evaluate consumers' lifestyles, considering that non-dieters and those low and moderate in dietary restraint may not be impacted by this information

American foulbrood in a honeybee colony: spore-symptom relationship and feedbacks between disease and colony development

Background: The most severe bacterial disease of honeybees is American foulbrood (AFB. The epidemiology of AFB is driven by the extreme spore resilience, the difficulty of bees to remove these spores, and the considerable incidence of undetected spore-producing colonies. The honeybee collective defence mechanisms and their feedback on colony development, which involves a division of labour at multiple levels of colony organization, are difficult to model. To better predict disease outbreaks we need to understand the feedback between colony development and disease progression within the colony. We therefore developed Bayesian models with data from forty AFB-diseased colonies monitored over an entire foraging season to (i) investigate the relationship between spore production and symptoms, (ii) disentangle the feedback loops between AFB epidemiology and natural colony development, and (iii) discuss whether larger insect societies promote or limit within-colony disease transmission. Results: Rather than identifying a fixed spore count threshold for clinical symptoms, we estimated the probabili-ties around the relationship between spore counts and symptoms, taking into account modulators such as brood amount/number of bees and time post infection. We identified a decrease over time in the bees-to-brood ratio related to disease development, which should ultimately induce colony collapse. Lastly, two contrasting theories pre-dict that larger colonies could promote either higher (classical epidemiological SIR-model) or lower (increasing spatial nest segregation and more effective pathogen removal) disease prevalence. Conclusions: AFB followed the predictions of the SIR-model, partly because disease prevalence and brood removal are decoupled, with worker bees acting more as disease vectors, infecting new brood, than as agents of social immu-nity, by removing infected brood. We therefore established a direct link between disease prevalence and social group size for a eusocial insect. We furthermore provide a probabilistic description of the relationship between AFB spore counts and symptoms, and how disease development and colony strength over a season modulate this relationship. These results help to better understand disease development within honeybee colonies, provide important estimates for further epidemiological modelling, and gained important insights into the optimal sampling strategy for practical beekeeping and honeybee research

Digital implementation of a wavelet-based event detector for cardiac pacemakers

This paper presents a digital hardware implementation of a novel wavelet-based event detector suitable for the next generation of cardiac pacemakers. Significant power savings are achieved by introducing a second operation mode that shuts down 2/3 of the hardware for long time periods when the pacemaker patient is not exposed to noise, while not degrading performance. Due to a 0.13-mu m CMOS technology and the low clock frequency of 1 kHz, leakage power becomes the dominating power source. By introducing sleep transistors in the power-supply rails, leakage power of the hardware being shut off is reduced by 97%. Power estimation on RTL-level shows that the overall power consumption is reduced by 67% with a dual operation mode. Under these conditions, the detector is expected to operate in the sub-mu W region. Detection performance is evaluated by means of databases containing electrograms to which five types of exogenic and endogenic interferences are added. The results show that reliable detection is obtained at moderate and low signal to noise-ratios (SNRs). Average detection performance in terms of detected events and false alarms for 25-dB SNR is P-D = 0.98 and P-FA = 0.014, respectively

A variable-rate Viterbi decoder in 130-nm CMOS: design, measurements, and cost of flexibility

This paper discusses design and measurements of a flexible Viterbi decoder fabricated in 130-nm digital CMOS. Flexibility was incorporated by providing various code rates and modulation schemes to adjust to varying channel conditions. Based on previous trade-off studies, flexible building blocks were carefully designed to cause as little area penalty as possible. The chip runs down to a minimal core supply of 0.8V. It turns out that striving for more modulation schemes is beneficial in terms of power consumption once the price is paid for accepting different code rates viz. radices in the trellis and survivor path units

SLU:s verksamhet med bin

Under 2014/15 var vi sammanlagt sju personer i den grupp på SLU som arbetar med olika aspekter på hälsa och sjukdomar hos honungsbin. Gruppen utökades under sommaren 2014 med två nya forskarstuderande/doktorander; Sepideh Lamei som ska studera mjölksyrabakteriers betydelse för bins hälsa, och Srinivas Thaduri som ska studera sammansättningen av mikroorganismer hos den gotländska population av bin som överlevt och klarar sig utan behandling mot varroakvalstret (de så kallade Bondbina). En kortfattad beskrivning av deras respektive projekt kan ni läsa om längre ned i texten

Effect of oral infection with Kashmir bee virus and Israeli acute paralysis virus on bumblebee (Bombus terrestris) reproductive success

Israeli acute paralysis virus (IAPV) together with Acute bee paralysis virus (ABPV) and Kashmir bee virus (KBV) constitute a complex of closely related dicistroviruses. They are infamous for their high mortality after injection in honeybees. These viruses have also been reported in non-Apis hymenopteran pollinators such as bumblebees, which got infected with IAPV when placed in the same greenhouse with IAPV infected honeybee hives. Here we orally infected Bombus terrestris workers with different doses of either IAPV or KBV viral particles. The success of the infection was established by analysis of the bumblebees after the impact studies: 50 days after infection. Doses of 0.5 x 10(7) and 1 x 10(7) virus particles per bee were infectious over this period, for IAPV and KBV respectively, while a dose of 0.5 x 10(6) IAPV particles per bee was not infectious. The impact of virus infection was studied in micro-colonies consisting of 5 bumblebees, one of which becomes a pseudo-queen which proceeds to lay unfertilized (drone) eggs. The impact parameters studied were: the establishment of a laying pseudo-queen, the timing of egg-laying, the number of drones produced, the weight of these drones and worker mortality. In this setup KBV infection resulted in a significant slower colony startup and offspring production, while only the latter can be reported for IAPV. Neither virus increased worker mortality, at the oral doses used. We recommend further studies on how these viruses transmit between different pollinator species. It is also vital to understand how viral prevalence can affect wild bee populations because disturbance of the natural host-virus association may deteriorate the already critically endangered status of many bumblebee species