26 research outputs found
IMPACT OF GEOLOCATION DATA ON AUGMENTED REALITY USABILITY: A COMPARATIVE USER TEST
While the use of location-based augmented reality (AR) for education has demonstrated benefits on participantsâ motivation, engagement, and on their physical activity, geolocation data inaccuracy causes augmented objects to jitter or drift, which is a factor in downgrading user experience. We developed a free and open source web AR application and conducted a comparative user test (n = 54) in order to assess the impact of geolocation data on usability, exploration, and focus. A control group explored biodiversity in nature using the system in combination with embedded GNSS data, and an experimental group used an external module for RTK data. During the test, eye tracking data, geolocated traces, and in-app user-triggered events were recorded. Participants answered usability questionnaires (SUS, UEQ, HARUS).We found that the geolocation data the RTK group was exposed to was less accurate in average than that of the control group. The RTK group reported lower usability scores on all scales, of which 5 out of 9 were significant, indicating that inaccurate data negatively predicts usability. The GNSS group walked more than the RTK group, indicating a partial effect on exploration. We found no significant effect on interaction time with the screen, indicating no specific relation between data accuracy and focus. While RTK data did not allow us to better the usability of location-based AR interfaces, results allow us to assess our systemâs overall usability as excellent, and to define optimal operating conditions for future use with pupils
CHARACTERIZATION AND VALORIZATION OF MAIZE LANDRACES FROM VALLE D'AOSTA
During 1949-1950 in Italy begun a formal investigation to characterize
maize (Zea mays L.) cultivation. In 1954, started a project for the
sampling of all Italian maize landraces; this work ended with the
collection of 562 different accessions collected in all regions with the
exception of Valle dâAosta, even if historical cultivation of maize in this
Region is well documented.
In Italy maize landraces have been extensively grown until the mid of the
XX century when the cultivation of hybrid took place due to their
significant agronomic performances. Despite that, being Valle dâAosta a
mountain region where intensive maize cultivation never started, it was
possible to preserve the presence of some landraces. These local materials,
which are still cultivated, mainly at domestic level, have high importance
from a genetic and historical point of view. Recently, 5 maize landraces
from Valle dâAosta and 2 landraces from the adjacent Canavese (Piedmont)
have been collected and subjected to historic, morphologic and genetic
characterization. These landraces were named after the sampling location as
it follows: Arnad, Arnad-Crest, Chatillon, Entrebin, Perloz, Bianco
Canavese, and Rostrato Canavese.
Firstly, on these 6 varieties the historic characterization has been
carried out. Information and photographs have been searched in local
archives and this was crucial to prove their long presence in all the
sampling sites under study. From this historic reconstruction, the variety
Entrebin resulted as the one that is better historically characterized.
To study the variability and differentiation of landraces from Valle
dâAosta, the genetic characterization was performed by the means of 10 SSR
markers tested on 20 samples from each landrace. This study highlighted a
significant genetic variability among the landraces and, especially, a good
level of differentiation between the accessions under investigation. This
last result may be explained by the long reproductive isolation experienced
by these materials. Complete morphological characterization is actually
ongoing. Preliminary morphological observations revealed that these
landraces have, generally, flint kernels with the exception of Bianco
Canavese (dent) whose color is variable from white (Bianco Canavese) to
dark red (Chatillon). Arnad landrace showed 8 kernel rows, probably being
an Eight-rowed Flint while the others presented more rows, like many
Derived Races. Interestingly, Perloz and Rostrato Canavese showed kernels
with an apical beak which was more pronounced in the latter. This suggest
that these two landraces belong to the âRostrataâ group, which is common in
mountain areas.
The present work confirms the importance of mountain areas in conserving
biodiversity and increases the rich Italian maize germplasm with materials
well adapted to marginal areas. Such new genetic variability may be used to
breed new materials for a more resilient agriculture
Crucial neuroprotective roles of the metabolite BH4 in dopaminergic neurons
Dopa-responsive dystonia (DRD) and Parkinsonâs disease (PD) are movement disorders caused by the dysfunction of nigrostriatal dopaminergic neurons. Identifying druggable pathways and biomarkers for guiding therapies is crucial due to the debilitating nature of these disorders. Recent genetic studies have identified variants of GTP cyclohydrolase-1 (GCH1), the rate-limiting enzyme in tetrahydrobiopterin (BH4) synthesis, as causative for these movement disorders. Here, we show that genetic and pharmacological inhibition of BH4 synthesis in mice and human midbrain-like organoids accurately recapitulates motor, behavioral and biochemical characteristics of these human diseases, with severity of the phenotype correlating with extent of BH4 deficiency. We also show that BH4 deficiency increases sensitivities to several PD-related stressors in mice and PD human cells, resulting in worse behavioral and physiological outcomes. Conversely, genetic and pharmacological augmentation of BH4 protects mice from genetically- and chemically induced PD-related stressors. Importantly, increasing BH4 levels also protects primary cells from PD-affected individuals and human midbrain-like organoids (hMLOs) from these stressors. Mechanistically, BH4 not only serves as an essential cofactor for dopamine synthesis, but also independently regulates tyrosine hydroxylase levels, protects against ferroptosis, scavenges mitochondrial ROS, maintains neuronal excitability and promotes mitochondrial ATP production, thereby enhancing mitochondrial fitness and cellular respiration in multiple preclinical PD animal models, human dopaminergic midbrain-like organoids and primary cells from PD-affected individuals. Our findings pinpoint the BH4 pathway as a key metabolic program at the intersection of multiple protective mechanisms for the health and function of midbrain dopaminergic neurons, identifying it as a potential therapeutic target for PD
A Low-Power Programmable Dynamic Frequency Divider
In this paper, a solution to realize a low-power programmable frequency divider using dynamic logic is proposed. By cascading compact dual-modulus divider slice with recursive feedback mechanisms, any dividing ratio is easily implemented. A 5-stages 0.18 mum CMOS implementation demonstrates a power consumption factor as low as 235 nW/MHz under 1.2 V supply for high dividing ratios
A MEMS-based 2.4-GHz sub-sampling RF front-end for advanced healthcare applications
This work presents a Bulk Acoustic Wave (BAW) resonator based 2.4-GHz front-end compliant to the Bluetooth LE standard and targeting advanced biomedical applications. A new transceiver architecture is proposed that combines BAW resonators and a sub-sampling architecture. It takes advantage of the high-Q of BAW resonators to perform channel filtering directly at RF. At the same time it also carries-out the critical anti-alias filtering required by the subsequent sub-sampling down-conversion mixer generating quadrature samples of the selected channel at baseband. The high-Q resonator is also used in the frequency synthesis to provide a low phase noise reference clock. The front-end has been designed and integrated in a 0.18-Όm standard CMOS process and the principle is validated with simulations and measurement results. © 2011 IEEE
Building Blocks for an Ultra Low-Power MEMS-based Radio
The recent advances made in MEMS and particularly in RF MEMS technology are enabling new architectures for the integration of RF transceivers with improved performance and smaller size. Several fundamental building blocks benefit from the availability of high-Q resonators in the RF front-end and the frequency synthesizer to lower power consumption, phase noise and die area. In addition, the compatibility of MEMS with CMOS opens the door to a higher integration level using for example an above-Q approach. This paper presents the recent work made at CSEM in the field of low-power transceiver for wireless sensor network applications. It first presents the high-Q resonators, including the BAW resonators used in the RF front-end and in the RF oscillator together with MEMS used in the low frequency reference oscillators. These MEMS are activated thanks to an AlN piezo layer avoiding the need for high voltage generation which is incompatible with the low-power and low-voltage requirement. These MEMS are also temperature compensated by the combination of additional layers and electronics means. The paper then focuses on the main building blocks that can take advantage of high-Q resonators. The fundamentals of oscillators built around high-Q devices is described, highlighting the basic trade-offs. It is also described how to take advantage of such devices within a receiver front-end
Thick a-Si:H p-i-n Diodes, produced by the VHF-GD Process: Spectral Response for Visible/Infrared Light and Current Transient
Frequency Synthesis for a Low-Power 2.4 GHz Receiver Using a BAW Oscillator and a Relaxation Oscillator
In this paper, a solution to realize local oscillators (LO) for a low power super-heterodyne receiver is presented. The first oscillator uses a bulk acoustic wave (BAW) resonator with high Q-factor. A quasi- harmonic quadrature relaxation oscillator with large tuning range is used to compensate for variations in the first oscillator and to cover the entire bandwidth for multiple channel selection