Solar radiation is an important driver of animal coloration, not only because of the effects of coloration on body temperature but also because coloration may protect from the deleterious effects of UV radiation. Indeed, dark coloration may protect from UV, but may increase the risk of overheating. In addition, the effect of coloration on thermoregulation should change with egg size, as smaller eggs have higher surface-volume ratios and greater convective coefficients than larger eggs, so that small eggs can dissipate heat quickly. We tested whether the reflectance of eggshells, egg spottiness, and egg size of the ground-nesting Kentish plover Charadrius alexandrinus is affected by maximum ambient temperature and solar radiation at breeding sites. We measured reflectance, both in the UV and human visible spectrum, spottiness, and egg size in photographs from a museum collection of plover eggshells. Eggshells of lower reflectance (darker) were found at higher latitudes. However, in southern localities where solar radiation is very high, eggshells are also of dark coloration. Eggshell coloration had no significant relationship with ambient temperature. Spotiness was site-specific. Small eggs tended to be light-colored. Thermal constraints may drive the observed spatial variation in eggshell coloration, which may be lighter in lower latitudes to diminish the risk of overheating as a result of higher levels of solar radiation. However, in southern localities with very high levels of UV radiation, eggshells are of dark coloration likely to protect embryos from more intense UV radiation. Egg size exhibited variation in relation to coloration, likely through the effect of surface area-to-volume ratios on overheating and cooling rates of eggs. Therefore, differential effects of solar radiation on functions of coloration and size of eggshells may shape latitudinal variations in egg appearance in the Kentish plover.

Journal Paper - Ecology and Evolution, pp 1-11, 2018 JOHN WILEY & SONS
DOI: 10.1002/ece3.4335    ISSN: 2045-7758    » doi

A 0.9-V ΔΣ modulator integrated into a 0.18-μm 2 CMOS technology for digitizing signals in low-power devices is presented in this paper. To do so, a cascade (multistage noise shaping) architecture based on an adder-less feedforward structure is proposed. The proposed modulator has a unity signal transfer function in both stages of the modulator in order to reduce the integrator´s output swings. To mitigate the failure of slow process corner in the weak inversion as well as to further diminish the power consumption of the presented modulator, a fully differential self- and bulk-biased inverter based operational transconductance amplifier is proposed. Experimental results are shown to demonstrate the efficiency of the proposed ΔΣ converter, showing state-of-the-art performance, by featuring 88.7-dB signal-to-noise ratio, 86.4-dB signal-to-noise plus distortion ratio, and 91-dB dynamic range within a signal bandwidth of 20 kHz, with a power dissipation of 103.4 μW when the circuit is clocked at 5.12 MHz.

Journal Paper - IEEE Transactions on Circuits and Systems I: Regular Papers IEEE
DOI: 10.1109/TCSI.2018.2854220    ISSN: 1549-8328    » doi

Abstract not avaliable

Conference - IEEE Int. Symposium on On-Line Testing and Robust System Design IOLTS 2018

Abstract not avaliable

Conference - Int. Symposium on Power and Timing Modeling, Optimization and Simulation PATMOS 2018

This paper exposes the problematic issue of not considering device variability and layout parasitic effects in optimization-based design of radiofrequency integrated circuits. Therefore, in order to handle these issues, a new design methodology that performs an all-inclusive optimization is proposed, by taking into account the process variability, and, performing the complete layout automatically while performing an accurate parasitic extraction during the optimization for each candidate solution. Furthermore, the problematic inductor parasitics are also taken into account with EM-accuracy, by using a state-of-the-art surrogate modelling technique. The methodology was applied in the design and optimization of a low-noise amplifier, obtaining a set of extremely robust designs ready for fabrication.

Conference - Int. Conf. on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design SMACD 2018