326 research outputs found
Massive MIMO goes Sub-GHz: Implementation and Experimental Exploration for LPWANs
Low-Power Wide-Area Networks operating in the unlicensed bands are being
deployed to connect a rapidly growing number of Internet-of-Things devices.
While the unlicensed sub-GHz band offers favorable propagation for long-range
connections, measurements show that the energy consumption of the nodes is
still mostly dominated by the wireless transmission affecting their autonomy.
We investigate the potential benefits of deploying massive MIMO technology to
increase system reliability and at the same time support low-energy devices
with good coverage at sub-GHz frequencies. The impact of different antenna
configurations and propagation conditions is analyzed. Both actual average
experienced array gain and channel hardening are examined. The assessment
demonstrates the effect of channel hardening as well as the potential benefits
of the experienced array gain. These measurements serve as a first assessment
of the channel conditions of massive MIMO at sub-GHz frequencies and are, to
the best of our knowledge, the first of its kind
Financial Transaction Tax: Small is Beautiful
The case for taxing financial transactions merely to raise more revenues from the financial sector is not particularly strong. Better alternatives to tax the financial sector are likely to be available. However, a tax on financial transactions could be justified in order to limit socially
undesirable transactions when more direct means of doing so are unavailable for political or
practical reasons. Some financial transactions are indeed likely to do more harm than good,
especially when they contribute to the systemic risk of the financial system. However, such a
financial transaction tax should be very small, much smaller than the negative externalities in
question, because it is a blunt instrument that also drives out socially useful transactions.
There is a case for taxing over-the-counter derivative transactions at a somewhat higher rate
than exchange-based derivative transactions. More targeted remedies to drive out socially
undesirable transactions should be sought in parallel, which would allow, after their
implementation, to reduce or even phase out financialtransaction taxes
Unprecedented early flux excess in the hybrid 02es-like type Ia supernova 2022ywc indicates interaction with circumstellar material
We present optical photometric and spectroscopic observations of the
02es-like type Ia supernova (SN) 2022ywc. The transient occurred in the
outskirts of an elliptical host galaxy and showed a striking double-peaked
light curve with an early excess feature detected in the ATLAS orange and cyan
bands. The early excess is remarkably luminous with an absolute magnitude , comparable in luminosity to the subsequent radioactively-driven second
peak. The spectra resemble the hybrid 02es-like SN 2016jhr, that is considered
to be a helium shell detonation candidate. We investigate different physical
mechanisms that could power such a prominent early excess and rule out massive
helium shell detonation, surface Ni distribution and ejecta-companion
interaction. We conclude that SN ejecta interacting with circumstellar material
(CSM) is the most viable scenario. Semi-analytical modelling with MOSFiT
indicates that SN ejecta interacting with M of CSM at a
distance of cm can explain the extraordinary light curve. A
double-degenerate scenario may explain the origin of the CSM, either by
tidally-stripped material from the secondary white dwarf, or disk-originated
matter launched along polar axes following the disruption and accretion of the
secondary white dwarf. A non-spherical CSM configuration could suggest that a
small fraction of 02es-like events viewed along a favourable line of sight may
be expected to display a very conspicuous early excess like SN 2022ywc.Comment: Accepted to ApJL after minor revisio
Dependable Interference-Aware Time-Slotted Channel Hopping for Wireless Sensor Networks
Extension of Type 2 Diabetes Genome-Wide Association Scan Results in the Diabetes Prevention Program
OBJECTIVE— Genome-wide association scans (GWASs) have identified novel diabetes-associated genes. We evaluated how these variants impact diabetes incidence, quantitative glycemic traits, and response to preventive interventions in 3,548 subjects at high risk of type 2 diabetes enrolled in the Diabetes Prevention Program (DPP), which examined the effects of lifestyle intervention, metformin, and troglitazone versus placebo
Family- and population-based designs identify different rare causal variants
Both family- and population-based samples are used to identify genetic variants associated with phenotypes. Each strategy has demonstrated advantages, but their ability to identify rare variants and genes containing rare variants is unclear. To compare these two study designs in the identification of rare causal variants, we applied various methods to the population- and family-based data simulated by the Genetic Analysis Workshop 17 with knowledge of the simulated model. Our results suggest that different variants can be identified by different study designs. Family-based and population-based study designs can be complementary in the identification of rare causal variants and should be considered in future studies
Energy-efficient link-layer jamming attacks against wireless sensor network MAC protocols
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