Benchmarking CPUs and GPUs on embedded platforms for software receiver usage

Smartphones containing multi-core central processing units (CPUs) and powerful many-core graphics processing units (GPUs) bring supercomputing technology into your pocket (or into our embedded devices). This can be exploited to produce power-efficient, customized receivers with flexible correlation schemes and more advanced positioning techniques. For example, promising techniques such as the Direct Position Estimation paradigm or usage of tracking solutions based on particle filtering, seem to be very appealing in challenging environments but are likewise computationally quite demanding. This article sheds some light onto recent embedded processor developments, benchmarks Fast Fourier Transform (FFT) and correlation algorithms on representative embedded platforms and relates the results to the use in GNSS software radios. The use of embedded CPUs for signal tracking seems to be straight forward, but more research is required to fully achieve the nominal peak performance of an embedded GPU for FFT computation. Also the electrical power consumption is measured in certain load levels.Peer ReviewedPostprint (published version

Matrix change of bone grafting substitute after implantation into guinea pig bulla

Background: Many different surgical techniques have been developed to remove open mastoid cavities. In addition to autologous materials, alloplastic substances have been used. A very slow absorption of these materials and extrusion reactions have been reported. We investigated a newly developed, highly porous bone grafting material to eliminate open mastoid cavities, in an animal model. To characterise the transformation process, the early tissue reactions were studied in relation to the matrix transformation of the bone material. Material and methods: NanoBone (NB), a highly porous bone grafting material based on calcium phosphate and silica, was filled into the open bullae from 20 guinea pigs. The bullae were examined histologically. Energy dispersive X-ray spectroscopy (EDX) was used to investigate the change in the elemental composition at different sampling times. The surface topography of the sections was examined by electron microscopy. Results: After 1 week, periodic acid-Schiffs (PAS) staining demonstrated accumulation of glycogen and proteins, particularly in the border area of the NB particles. After 2 weeks, the particles were evenly coloured after PAS staining. EDX analysis showed a rapid absorption of the silica in the bone grafting material. Conclusions: NanoBone showed a rapid matrix change after implantation in the bullae of guinea pigs. The absorption of the silica matrix and replacement by PAS-positive substances like glycoproteins and mucopolysaccharides seems to play a decisive role in the degradation processes of NB. This is associated with the good osteoinductive properties of the material

Phonocardiogram Segmentation with Tiny Computing

The stethoscope is a daily used tool that allows medical doctors to diagnose common cardiovascular diseases by listening to heart sounds. However, dedicated medical training is required to operate it. Numerous machine learning techniques have been used in attempts to automate this process and have yielded highly accurate results. However, creating a low power, portable, economical, and accurate machine learning stethoscope calls for tiny processing of phonocardiograms i.e., heart sound digital processing to run within an embedded device. To address the need to deploy the solution within a constrained tiny device, we propose an 8-bit deep learning model with low embedded FLASH and RAM utilization of 126 KiB and 45 KiB respectively, which is optimized for inference on an off-the-shelf STM32H7 microcontroller with an inference time of 12 ms, in 126KiB FLASH and 45 KiB RAM being 91.65% accurate

Cultural fairness of the Digit Vigilance Test

This study was designed to examine the cultural fairness of the Digit Vigilance Test by comparing performance on the test between Chinese and American participants. Thirty-five Chinese undergraduates, 12 male and 23 female, were recruited as participants. Their scores on the test, specifically the time and error scores, were compared with the published American norms. The findings indicated equivalent performance of the two samples on the test, suggesting the cultural fairness of the Digit Vigilance Test. Nevertheless, generalization of the present findings to other Chinese populations should take into consideration the unique characteristics of the sample in this study.published_or_final_versio

Adaptable Radiative Transfer Innovations for Submillimeter Telescopes (ARTIST)

Submillimeter observations are a key for answering many of the big questions in modern-day astrophysics, such as how stars and planets form, how galaxies evolve, and how material cycles through stars and the interstellar medium. With the upcoming large submillimeter facilities ALMA and Herschel a new window will open to study these questions. ARTIST is a project funded in context of the European ASTRONET program with the aim of developing a next generation model suite for comprehensive multi-dimensional radiative transfer calculations of the dust and line emission, as well as their polarization, to help interpret observations with these groundbreaking facilities.Comment: 4 pages, 1 figure; to appear in "IAU Symposium 270: Computational Star formation", Eds. J. Alves, B. Elmegreen, J. Girart, V. Trimbl

Ultraspinning instability of rotating black holes

Rapidly rotating Myers-Perry black holes in d>5 dimensions were conjectured to be unstable by Emparan and Myers. In a previous publication, we found numerically the onset of the axisymmetric ultraspinning instability in the singly-spinning Myers-Perry black hole in d=7,8,9. This threshold signals also a bifurcation to new branches of axisymmetric solutions with pinched horizons that are conjectured to connect to the black ring, black Saturn and other families in the phase diagram of stationary solutions. We firmly establish that this instability is also present in d=6 and in d=10,11. The boundary conditions of the perturbations are discussed in detail for the first time and we prove that they preserve the angular velocity and temperature of the original Myers-Perry black hole. This property is fundamental to establish a thermodynamic necessary condition for the existence of this instability in general rotating backgrounds. We also prove a previous claim that the ultraspinning modes cannot be pure gauge modes. Finally we find new ultraspinning Gregory-Laflamme instabilities of rotating black strings and branes that appear exactly at the critical rotation predicted by the aforementioned thermodynamic criterium. The latter is a refinement of the Gubser-Mitra conjecture.Comment: 38 pages, 6 figures, 1 tabl

Floristic Composition and Natural History Characteristics of Dry Forests in the Pacific

We compare the floristic composition of tropical dry forests at the stand level using Gentry's transect method (0.1 ha) in some of the largest and highest-quality remaining fragments in the Pacific (Hawai'i, 15 sites; Fiji, 9; the Marianas, 3; the Marquesas, 6; New Caledonia, 7) and compare results with neotropical dry forests. A total of 299 species or morphospecies =2.5 cm diameter at breast height were identified from all 40 sites in the Pacific. Rubiaceae (28 spp.), Euphorbiaceae (25 spp.), Fabaceae (23 spp.), Sapindaceae (18 spp.), and Myrtaceae (17 spp.) were the most speciose families in Pacific dry forest; however, no family dominated across regions in the Pacific. The most common species by frequency and density in each region were native with the exception of Hawai'i, which contains a high number of nonnative species. Observed and estimated (Chao 2) levels of native species richness show that New Caledonia and Fiji contain the highest species richness followed by Hawai'i, the Marianas, and the Marquesas. There is very little overlap at the native species level among regions, with Hawaiian dry forests the most dissimilar at the native species, genus, and family level and New Caledonia and Fiji the most similar. Unlike mainland neotropical dry forest, dry forests in the Pacific contain very few deciduous species and a low proportion of wind-dispersed species.There is a high proportion of dioecious species in Hawai'i, which is similar to the neotropics; however, other Pacific regions have fewer dioecious species

Collisions of red giants in galactic nuclei

In stellar-dense environments, stars can collide with each other. For collisions close to a supermassive black hole (SMBH), the collisional kinetic energy can be so large that the colliding stars can be completely destroyed, potentially releasing an amount of energy comparable to that of a supernova. These violent events have been examined mostly analytically, with the non-linear hydrodynamical effects being left largely unstudied. Using the moving-mesh hydrodynamics code {\small AREPO}, we investigate high-velocity ($>10^{3}$ km/s) collisions between 1M$_{\odot}$ giants with varying radii, impact parameters, and initial approaching velocities, and estimate their observables. Very strong shocks across the collision surface efficiently convert $\gtrsim10\%$ of the initial kinetic energy into radiation energy. The outcome is a gas cloud expanding supersonically, homologously, and quasi-spherically, generating a flare with a peak luminosity $\simeq 10^{41}-10^{44}$ erg/s in the extreme UV band ($\simeq 10$ eV). The luminosity decreases approximately following a power-law $t^{-0.7}$ initially, then $t^{-0.4}$ after $t\simeq$10 days at which point it would be bright in the optical band ($\lesssim 1$eV). Subsequent, and possibly even brighter, emission would be generated due to the accretion of the gas cloud onto the nearby SMBH, possibly lasting up to multi-year timescales. This inevitable BH-collision product interaction can contribute to the growth of BHs at all mass scales, in particular, seed BHs at high redshifts. Furthermore, the proximity of the events to the central BH makes them a potential tool for probing the existence of dormant BHs, even very massive ones which cannot be probed by tidal disruption events.Comment: 16 pages, 14 figures, 2 tables, submitted to MNRAS, comments welcome, movies here: https://www.youtube.com/playlist?list=PLxLK3qI02cQd9lyIo6DIqm1tQnx_-G3U

On the Threat of Systematic Jamming of GNSS

This paper presents a study of the threat of malicious interference to GNSS and examines the special case where the jamming device is incrementally more sophisticated than a typical always-on interference source. The concept of a systematic jamming attack is considered, where the interference signal is intentionally synchronized with the GNSS signals, with the intention of causing maximum disruption with the minimum power expenditure. Various attack methodologies are examined for the case of a civilian L1 receiver. It is shown that, depending on the attack strategy, the target signal and the target receiver, data-recovery, navigation and timing can be denied to a user with some tens of decibels less average power than a traditional jamming attack. It is further shown that some attacks may be capable to effectively deny some receiver functionality in a subtle manner such that presence of the malicious interference goes undetected. Key signal and receiver features that expose a vulnerability are identified and some means of improving receiver robustness are provided