241 research outputs found
New material of Alierasaurus ronchii (Synapsida, Caseidae) from the Permian of Sardinia (Italy), and its phylogenetic affinities
New characters of the giant caseid Alierasaurus ronchii are described here based
on material recovered from the type locality in the Permian deposits of Cala del Vino
Formation (Sardinia NW) and additional preparation of the previously collected material.
All new described osteological elements are characterized by the same state of
preservation and, given the absence of double elements and the total compatibility in
absolute size, the new material can be attributed without doubt to the holotypic individual
of A. ronchii. Highly diagnostic material includes a caudal neural spine with a broad
bifid distal termination. This represents a synapomorphy characterizing the more
derived caseids, thus fully confirming the attribution of the Sardinian specimen to
Caseidae. Also the other vertebral material and newly collected ribs show a typical
caseid structure, fully consistent with the previously published material. Despite the
highly partial nature of Alierasaurus, the taxon was included in a recent phylogenetic
analysis of caseids to investigate its phylogenetic position within the monophyletic
Caseasauria. Alierasaurus falls as the sister taxon of Cotylorhynchus, and is autapomorphic
in the general construction of MT-IV and proximal phalanx IV-I. The absolute
size of the newly recovered material confirms a gigantic body size for Alierasaurus,
comparable, if not greater, to that of the huge North American species Cotylorhynchus
hancocki (up to 6 m in length). Such gigantic adult body size, closely correlated to its
herbivorous lifestyle, must have been selected during evolution of caseids, leading to
substantial advantages in terms of fitness
Power Management Circuits for Low-Power RF Energy Harvesters
The paper describes the design and implementation of power management circuits for
RF energy harvesters suitable for integration in wireless sensor nodes. In particular, we report the
power management circuits used to provide the voltage supply of an integrated temperature sensor
with analog-to-digital converter. A DC-DC boost converter is used to transfer efficiently the energy
harvested from a generic radio-frequency rectifier into a charge reservoir, whereas a linear regulator
scales the voltage supply to a suitable value for a sensing and conversion circuit. Implemented in
a 65 nm CMOS technology, the power management system achieves a measured overall efficiency
of 20%, with an available power of 4.5 μW at the DC-DC converter input. The system can sustain
a temperature measurement rate of one sample/s with an RF input power of −28 dBm, making it
compatible with the power levels available in generic outdoor environments
Permian tetrapod localities in the Nurra region (NW Sardinia, Italy): The State of the Art
The Nurra area in NW Sardinia is quite well known for the outcropping of a thick succession of more than 600 m of post‐ Variscan continental deposits (Fig. 1), with several dedicated studies and contribution already starting from the first half of the twentieth century (e.g. Lotti, 1931; Oosterbaan, 1936; Pecorini, 1962; Vardabasso, 1966; Gasperi and Gelmini, 1980)...Fil: Romano, Marco. University of the Witwatersrand; SudáfricaFil: Citton, Paolo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Ronchi, Ausonio. Università di Pavia; ItaliaFil: Nicosia, Umberto. Università di Roma; Itali
Soft Linear Logic and Polynomial Complexity Classes
AbstractWe describe some results inspired to Lafont's Soft Linear Logic (SLL) which is a subsystem of second-order linear logic with restricted rules for exponentials, correct and complete for polynomial time computations. SLL is the basis for the design of type assignment systems for lambda-calculus, characterizing the complexity classes PTIME, PSPACE and NPTIME. PTIME is characterized by a type assignments system where types are a proper subset of SLL formulae. The characterization consists in the fact that a well typed term can be reduced to normal form by a number of beta-reductions polynomial in its lenght, and moreover all polynomial time functions can be computed by well typed terms. PSPACE is characterized by a type assignment system obtained from the previous one, by extending the set of types by a type for booleans, and the lambda-calculus by two boolean constants and a conditional constructor. The system assigns types to terms in such a way that the evaluation of programs (closed terms of type boolean) can be performed carefully in polynomial space. Moreover all polynomial space decision problems can be computed by terms typable in this system. In order to characterize NPTIME we extend the lambda-calculus by a nondeterministic choice operator, and the system by a rule for dealing with this new term constructor
A Low-Power Sigma-Delta Modulator for Healthcare and Medical Diagnostic Applications
This paper presents a switched-capacitor Sigma-Delta modulator designed in 90-nm CMOS technology, operating at 1.2-V supply voltage. The modulator targets healthcare and medical diagnostic applications where the readout of small-bandwidth signals is required. The design of the proposed A/D converter was optimized to achieve the minimum power consumption and area. A remarkable performance improvement is obtained through the integration of a low-noise amplifier with modified Miller compensation and rail-to-rail output stage. The manuscript also presents a set of design equations, from the small-signal analysis of the amplifier, for an easy design of the modulator in different technology nodes. The Sigma-Delta converter achieves a measured 96-dB dynamic range, over a 250-Hz signal bandwidth, with an oversampling ratio of 500. The power consumption is 30 μW, with a silicon area of 0.39 mm²
Effect of temperature increase during the tableting of pharmaceutical materials
Scale-up of tableting process is particularly difficult due to specific concerns related exclusively to the process itself and that cannot be determined on a smaller scale, which are the effect of compression speed and the build-up of heat due to the length of the compaction operations. In this work, it has been simulated the rise of temperature observed during the tablets manufacturing in a full production scale by means of an appropriate modification of a R&D rotary tablet machine. Four common pharmaceutical excipients, characterized by different chemical nature, consolidation behaviour and temperature sensitiveness have been analysed in terms of compaction mechanism (Heckel and energy analysis) and tabletability, in order to verify any effect of the increase of temperature. The results showed a relevance of the temperature on mechanical tablets properties only on materials characterized by low temperature thermal transitions (melting or glass transition), while, for compounds which do not exhibit thermal events at low temperature, it becomes less important for ductile materials and irrelevant for brittle materials. Heckel analysis highlighted a noticeable increase of ductility only in those materials whose tablets mechanical properties depended on the temperature. On the other hand, energy analysis showed low sensitivity failing to identify any temperature effect on compaction materials properties. This work showed how to simulate the process of temperature rise on a small scale and the influence of temperature on materials compaction properties. The use of a modified tableting machine, able to control the temperature and moisture levels and also capable of monitoring the punch movements, resulted in identifying the effect of temperature both on mechanical and compaction properties on materials. Thus, it represents a valuable tool in order to provide useful information at an early stage during the development of tablets formulations
A Logical Account of PSPACE
International audienceThe Soft Type Assignment system has been introduced as a language for Polytime Computations. In this work we extend the language by boolean additives constants obtaining a system named BSTA which we will show to be correct and complete for the complexity class of problem decidable in polynomial space
Non-thermal light-assisted resistance collapse in a VO-based Mott-insulator device
The insulator-to-metal transition in Mott insulators is the key mechanism for
a novel class of electronic devices, belonging to the Mottronics family.
Intense research efforts are currently devoted to the development of specific
control protocols, usually based on the application of voltage, strain,
pressure and light excitation. The ultimate goal is to achieve the complete
control of the electronic phase transformation, with dramatic impact on the
performance, for example, of resistive switching devices. Here, we investigate
the simultaneous effect of external voltage and excitation by ultrashort light
pulses on a single Mottronic device based on a VO epitaxial thin film.
The experimental results, supported by finite-element simulations of the
thermal problem, demonstrate that the combination of light excitation and
external electrical bias drives a volatile resistivity drop which goes beyond
the combined effect of laser and Joule heating. Our results impact on the
development of protocols for the non-thermal control of the resistive switching
transition in correlated materials
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