Dung Beetles Eat Acorns to Increase Their Ovarian Development and Thermal Tolerance

Animals eat different foods in proportions that yield a more favorable balance of nutrients. Despite known examples of these behaviors across different taxa, their ecological and physiological benefits remain unclear. We identified a surprising dietary shift that confers ecophysiological advantages in a dung beetle species. Thorectes lusitanicus, a Mediterranean ecosystem species adapted to eat semi-dry and dry dung (dung-fiber consumers) is also actively attracted to oak acorns, consuming and burying them. Acorn consumption appears to confer potential advantages over beetles that do not eat acorns: acorn-fed beetles showed important improvements in the fat body mass, hemolymph composition, and ovary development. During the reproductive period (October-December) beetles incorporating acorns into their diets should have greatly improved resistance to low-temperature conditions and improved ovarian development. In addition to enhancing the understanding of the relevance of dietary plasticity to the evolutionary biology of dung beetles, these results open the way to a more general understanding of the ecophysiological implications of differential dietary selection on the ecology and biogeography of these insects

A CMOS fully-differential bandpass ΣΔ modulator using switched-current circuits

Comunicación presentada al "38 th MWSCAS" celebrado en Rio de janeiro del 13 al 16 de Agosto de 1995.This paper presents a fourth-order bandpass sigma-delta modulator that has been designed using fully-differential switched-current circuits in a 0.8μm CMOS technology. The modulator prototype has been obtained by applying a lowpass to bandpass transformation to a second-order lowpass ΣΔ modulator. Specifications are SNR [email protected]±15Khz, for a clock frequency of 1OMhz. Preliminary results from the fabricated prototype obtains the correct noise shaping up to 2.5Mhz clock frequency.Peer reviewe

Tools for Automated Design of ΣΔ Modulators

We present a set of CAD tools to design ΣΔ modulators. They use statistical optimization to calculate optimum specifications for the building blocks used in the modulators, and optimum sizes for the components in these blocks. Optimization procedures at the modulator level are equation-based, while procedures at the cell level are simulation-based. The toolset incorporates also an advanced ΣΔ behavioral simulator for monitoring and design space exploration. We include measurements taken from two silicon prototypes: 1) a 17bit@40kHz output rate fourth-order low-pass modulator; and 2) a [email protected] central freq@10kHz bandwidth band-pass modulator. The first uses SC fully-differential circuits in a 1.2μm CMOS double-metal double-poly technology. The second uses SI fully-differential circuits in a 0.8μm CMOS double-metal single-poly technology.This work has been supported by the CEE ESPRIT Program in the framework of the Project #8795 (AMFIS).Peer reviewe

Multi-bit cascade ΣΔ modulator for high-speed A/D conversion with reduced sensitivity to DAC errors

El pdf del artículo es la versión post-print.This paper presents a ΣΔ modulator (ΣΔM) which combines single-bit and multi-bit quantization in a cascade architecture to obtain high resolution with low oversampling ratio. It is less sensitive to the non-linearity of the DAC than those previously reported, thus enabling the use of very simple analog circuitry with neither calibration nor trimming required.This work has been supported by Spanish C.I.C.Y.T. under contract TIC97-0580.Peer reviewe

A 2.5MHz 55dB Switched-Current BandPass ΣΔ Modulator for AM Signal Conversion.

We present a Switched-Current (SI) fourth-order bandpass ΣΔ modulator IC prototype. It uses fully-differential circuits in 0.8μm CMOS technology to obtain a Dynamic Range (DR) larger than 55dB at 2.5MHz center frequency with 30kHz bandwidth - in accordance to the requirements of AM digital receivers. The prototype incorporates a single-ended to fully-differential current-mode buffer for testing purposes. The power consumption of the whole prototype (modulator plus buffer) is 60mW from a 5V supply voltage.This work has been supported by the European Union, under ESPRIT Project 8795-AMFIS.Peer reviewe

Visualization of multifractal superconductivity in a two-dimensional transition metal dichalcogenide in the weak-disorder regime

Eigenstate multifractality is a distinctive feature of non-interacting disordered metals close to a metal-insulator transition, whose properties are expected to extend to superconductivity. While multifractality in three dimensions (3D) only develops near the critical point for specific strong-disorder strengths, multifractality in 2D systems is expected to be observable even for weak disorder. Here we provide evidence for multifractal features in the superconducting state of an intrinsic weakly disordered single-layer NbSe$_2$ by means of low-temperature scanning tunneling microscopy/spectroscopy. The superconducting gap, characterized by its width, depth and coherence peaks' amplitude, shows a characteristic spatial modulation coincident with the periodicity of the quasiparticle interference pattern. Spatial inhomogeneity of the superconducting gap width, proportional to the local order parameter in the weak-disorder regime, follows a log-normal statistical distribution as well as a power-law decay of the two-point correlation function, in agreement with our theoretical model. Furthermore, the experimental singularity spectrum f($\alpha$) shows anomalous scaling behavior typical from 2D weakly disordered systems

Flow, viscoelastic and masticatory properties of tailor made thickened pea cream for people with swallowing problems

[EN] This study evaluated the flow, viscoelastic and masticatory properties of tailor made pea cream using different hydrocolloids, and the potential effect that saliva could have while chewing. The creams thickened with pectin, carboxymethyl cellulose, tara gum and konjac gum showed the weakest internal gel structure with highest values of loss tangent at 1Hz (0.49 +/- 0.07), slope of log elastic modulus versus log frequency (0.34 +/- 0.05) and maximum capacitance (0.07 +/- 0.02 Pa-1). The samples thickened with commercial hydrocolloids were affected the most by the presence of saliva, with a significant reduction in apparent viscosity at 10 s(-1), that ranged from 1500 mPas until 11000 mPas. These results demonstrate that it is possible to optimize the structure of thickened pea cream for dysphagia by using, for example, carboxymethyl cellulose, tara gum and konjac gum, because they provide a greater viscous component, and, therefore, a bolus that is more easy to swallow.The authors thank the "Ministerio Espanol de Ciencia e Innovaci.on" for the financial support provided through the RTI2018-098842-B-I00 Project.Talens Oliag, P.; Castells, ML.; Verdú, S.; Barat Baviera, JM.; Grau Meló, R. (2021). Flow, viscoelastic and masticatory properties of tailor made thickened pea cream for people with swallowing problems. Journal of Food Engineering. 292:1-10. https://doi.org/10.1016/j.jfoodeng.2020.110265S11029

Experimental Characterization of IdleTones in Second-Order Bandpass ΣΔ Modulators

This paper analyses the tonal behaviour of the quantization noise in second-order bandpass ΣΔ modulators. The analysis performed for lowpass modulators is extended to the bandpass case. As a result, closed form expressions for the frequency of idle tones are derived for different cases regarding the signal center frequency position. All these results have been validated by measurements from a silicon prototype using fully differential switched-current circuits implemented in a standard 0.8μm CMOS technology.This work has been supported by the Spanish CICYT Project TIC 97-0580.Peer reviewe

Comparative thermoregulation between different species of dung beetles (Coleoptera: Geotrupinae)

Insects can use thermoregulation to keep their body temperatures within a certain range in response to thermal stress situations. The mechanisms to regulate internal temperature depend on whether species are endothermic or ectothermic species, i.e., if the heat source is internal and/or external. In this study, the thermal stress response due to excess heat was examined in individuals belonging to different species of the Geotrupinae subfamily by using a standardized protocol based on infrared thermography. All the measured heat stress variables allow discrimination among the considered species to a greater or lesser extent. The body heating rate in the heat stress range, the critical thermal maximum and the stress start temperature were the most important variables in discriminating between apterous and winged individuals (R2 = 52.5%, 51.1% and 50.0%, respectively). Examining the degree of association between the physiological similarity of individuals and some species traits suggest that flying capability and daily activity are related with different thermal responses. Based on the obtained results, the Geotrupinae subfamily can be divided into three ecophysiological groups: good, medium and non-thermoregulators. Within these groups, apterism appears mainly in those species with the ability to actively decrease their body temperature. Our results indicate that this ability may be partially due to the management of water loss related with evaporative cooling.This work was supported by the Spanish research project CGL2011-25544 of the Ministerio de Economía y Competitividad, as well as by the F. P. I. fellowship BES-2012–052010 to B.G

A CMOS 0.8 μm fully differential current mode buffer for HF SI circuits

El pdf del artículo es la versión post-print.We present a high-frequency fully-differential current-mode buffer to interface off-chip currents with no significant degradation of the frequency response, and to measure current-mode ICs using standard equipment. It has been fabricated in a 0.8μm double-poly double-metal CMOS technology and features more than 37MHz bandwidth. In order to show its functionality, this unit has been incorporated to the front end of a Switched-Current Band-Pass ΣΔ modulator featuring 9 bit dynamic range at 10MHz clock frequency for a 30kHz signal bandwidth centered at 2.5MHz.Peer reviewe