3,103 research outputs found
DEVELOPMENT OF NANOSTRUCTURED CARBON-BASED PLATFORMS FOR ADVANCED GAS SENSING
No full textTra le applicazioni all'avanguardia di materiali a base di carbonio nanostrutturato, come grafene e nanotubi di carbonio (CNTs), l'analisi del respiro (i.e. breathomics), il monitoraggio ambientale e l'industria alimentare stanno oggigiorno sfidando la fisica, la chimica e l’ingegneria dei materiali a sviluppare piattaforme di sensori estremamente sensibili, affidabili e stabili, che siano in grado di rilevare piccolissime quantità (ordine dei ppb) di molecole di gas nell’ambiente che le circonda. In questa tesi, verrà presentato lo sviluppo di 6 piattaforme di sensori di gas. Queste piattaforme saranno sviluppate con carbonio nanostrutturato e avranno come scopo principale quello di discriminare potenziali patologie attraverso il riconoscimento di pattern molecolari presenti nel respiro esalato, nonché la loro possibile applicazione nel monitoraggio ambientale degli inquinanti e nell’industria alimentare.
Questo obbiettivo verrà realizzato sviluppando dapprima piattaforme a base di CNTs su un substrato di plastica o su silicio/ossido di silicio e successivamente a base di grafene su nitruro di silicio.
Verranno esplorati diversi metodi di funzionalizzazione sia per i CNTs che per il grafene, per aumentarne la sensitività, e verranno utilizzati diversi materiali per la funzionalizzazione, incluse nanoparticelle, molecole organiche o sali di diazonio.
Tecniche di spettroscopie Raman ed elettroniche unitamente a microscopia a forza atomica verranno utilizzare per caratterizzare i campioni, mentre le esposizioni di gas verranno effettuate in aria, condizione più simile a quella delle applicazioni finali dei sensori, cercando di indagare concentrazioni dei gas selezionati nel sub-ppm o di poche decine di ppm. L’analisi delle componenti principali (PCA) verrà utilizzata per testare le capacità di discriminazione dei gas delle piattaforme sviluppate.
Infine, uno dei nasi elettronici sviluppati verrà testato con il respiro esalato di soggetti sani o affetti da broncopneumopatie cronico ostruttive (COPD), dimostrando un’ottima capacità di discriminare e riconoscere le due classi di pazienti.Among forefront applications of nanostructured carbon materials such as graphene and nanotubes, breathomics, environmental monitoring and food industry are challenging physics, chemistry and device engineering to develop extremely sensitive, selective, and stable platform to recognize ppb amount of target molecules in the environment.
In this thesis, the development of 6 platforms will be presented. The platforms are based on nanostructured carbon aimed mostly to discriminate potential pathologies through pattern recognition in molecular fingerprint of breath samples, but also for environmental monitoring or food industry applications. This objective will be realized through properly developed devices based first on CNTs on a plastic substrate or on silicon/silicon oxide substrate and then on graphene on silicon nitride. Different kinds of functionalization techniques of graphene and CNTs will be explored to enhance the sensitivity of the pristine layers, as well as different functionalization materials, going from nanoparticles to organic molecules or diazonium salt precursors.
The characterization of the materials involves electron and Raman spectroscopies, as well as atomic force microscopy, while gas exposures are carried out in the lab environment, which is much closer to the destination of the developed sensors, trying to investigate a low-ppm range or sub-ppm range of the considered gases. The gas discrimination is assessed through principal component analysis (PCA).
Finally, one of the developed devices is exposed to the exhaled breath of healthy subjects or patients affected by chronic obstructive pulmonary diseases (COPD), demonstrating a remarkable capability to discriminate between healthy and sick patients
An assessment of the impact of possible CAP reform scenarios on Romanian agriculture
No full textUsing a simplified model, with key-variable the prices of two different possible scenarios of CAP reform after 2013 (moderate and radical), this paper present a comparison between the price effects of implementation of each reform scenario at 2015 horizon on Romanian agriculture. This short analysis shows that, under the presented hypotheses, the net welfare effect, due to the price changes, for the selected products, is positive in both reform scenarios, yet greater in the case of the radical reform. Integrated in the large context of Romanian development, it seems that the influence of CAP reform upon agriculture and rural areas will be most likely a gradual one: an interpenetration between the two scenarios is foreseeable, starting with the moderate reform that will dominate the period around 2013, the reform measures acquiring a more radical character afterwards.CAP reform, Romania, welfare effects, Agricultural and Food Policy,
Glutaminase activity and glutamine-dependent acid resistance in enteric bacteria
No full textMany neutralophilic bacteria have developed several strategies to overcome the life-threatening effect of the exposure to a mild-to-harsh acid stress [1]. Among these strategies, the amino acid-dependent systems were shown to be quite widespread amongst gram-positive and –negative bacteria, and their activities overlap so to cover a rather large pH range, from 6 to <2 [1]. Recently an acid resistance (AR) system relying on the amino acid glutamine, the most readily available amino acid in the free form, was shown to be operative in E. coli, L. reuteri and some Brucella species [2-4]. This system imports L-glutamine via the antiporter GadC, also a structural component of the glutamate-dependent AR system, and exports via GadC either glutamate or GABA, depending on whether only the deamination of glutamine into glutamate occurs, or glutamate is also decarboxylated to yield GABA by the enzyme GadB.
We have undertaken a bioinformatic analysis to study the distribution of the glutaminase-dependent AR system in enteric bacteria and developed two assays. The first assay was developed for a rapid screening of the glutaminase activity and the growth conditions that support its maximum expression. The second assay was developed to measure the amount of glutamate/GABA exported. Our results indicate that the glutamine-dependent AR is likely to be of prominent importance in enteric bacteria.
[1] Lund et al. (2014) FEMS MIcrobiol Rev 38:1091-125. [2] Lu et al. (2013) Cell Res 23:635–644. [3] Teixeira et al. (2014) Food Microbiol 42:172-180. [4] Freddi et al. (2017) Front Microbiol 8:2236
Rich, Sturmian, and trapezoidal words
No full textIn this paper we explore various interconnections between rich words, Sturmian words, and trapezoidal words. Rich words, first introduced by the second and third authors together with J. Justin and S. Widmer, constitute a new class of finite and infinite words characterized by having the maximal number of palindromic factors. Every finite Sturmian word is rich, but not conversely. Trapezoidal words were first introduced by the first author in studying the behavior of the subword complexity of finite Sturmian words. Unfortunately this property does not characterize finite Sturmian words. In this note we show that the only trapezoidal palindromes are Sturmian. More generally we show that Sturmian palindromes can be characterized either in terms of their subword complexity (the trapezoidal property) or in terms of their palindromic complexity. We also obtain a similar characterization of rich palindromes in terms of a relation between palindromic complexity and subword complexity
Residually stressed beams
No full textIn this paper we derive a theory for a linearly elastic residually stressed rod through an asymptotic analysis based on Γ-convergence
Discriminative Marginalized Probabilistic Neural Method for Multi-Document Summarization of Medical Literature
No full textAlthough current state-of-the-art Transformer-based solutions succeeded in a wide range for single-document NLP tasks, they still struggle to address multi-input tasks such as multi-document summarization. Many solutions truncate the inputs, thus ignoring potential summary-relevant contents, which is unacceptable in the medical domain where each information can be vital. Others leverage linear model approximations to apply multi-input concatenation, worsening the results because all information is considered, even if it is conflicting or noisy with respect to a shared background. Despite the importance and social impact of medicine, there are no ad-hoc solutions for multi-document summarization. For this reason, we propose a novel discriminative marginalized probabilistic method (DAMEN) trained to discriminate critical information from a cluster of topic-related medical documents and generate a multi-document summary via token probability marginalization. Results prove we outperform the previous state-of-the-art on a biomedical dataset for multi-document summarization of systematic literature reviews. Moreover, we perform extensive ablation studies to motivate the design choices and prove the importance of each module of our method
Revelio: Interpretable Long-Form Question Answering
No full textThe black-box architecture of pretrained language models (PLMs) hinders the interpretability of lengthy responses in long-form question answering (LFQA). Prior studies use knowledge graphs (KGs) to enhance output transparency, but mostly focus on non-generative or short-form QA. We present Revelio, a new layer that maps PLM's inner working onto a KG walk. Tests on two LFQA datasets show that Revelio supports PLM-generated answers with reasoning paths presented as rationales while retaining performance and time akin to their vanilla counterparts
Characterization Results for the Poset Based Representation of Topological Relations - I: Introduction and Models
No full text@article{DBLP:journals/informaticaSI/ForlizziN99,
author = {Luca Forlizzi and
Enrico Nardelli},
title = {Characterization Results for the Poset Based Representation
of Topological Relations - I: Introduction and Models.},
journal = {Informatica (Slovenia)},
volume = {23},
number = {2},
year = {1999},
bibsource = {DBLP, http://dblp.uni-trier.de}
Characterization Results for the Poset Based Representation of Topological Relations - II: Intersection and Union
No full text@article{DBLP:journals/informaticaSI/ForlizziN00,
author = {Luca Forlizzi and
Enrico Nardelli},
title = {Characterization Results for the Poset Based Representation
of Topological Relations - II: Intersection and Union.},
journal = {Informatica (Slovenia)},
volume = {24},
number = {1},
year = {2000},
bibsource = {DBLP, http://dblp.uni-trier.de}
System-on-chip Computing and Interconnection Architectures for Telecommunications and Signal Processing
No full textThis dissertation proposes novel architectures and design techniques targeting SoC building blocks for telecommunications and signal processing applications.
Hardware implementation of Low-Density Parity-Check decoders is approached at both the algorithmic and the architecture level. Low-Density Parity-Check codes are a promising coding scheme for future communication standards due to their outstanding error correction performance.
This work proposes a methodology for analyzing effects of finite precision arithmetic on error correction performance and hardware complexity. The methodology is throughout employed for co-designing the decoder. First, a low-complexity check node based on the P-output decoding principle is designed and characterized on a CMOS standard-cells library. Results demonstrate implementation loss below 0.2 dB down to BER of 10^{-8} and a saving in complexity up to 59% with respect to other works in recent literature. High-throughput and low-latency issues are addressed with modified single-phase decoding schedules. A new "memory-aware" schedule is proposed requiring down to 20% of memory with respect to the traditional two-phase flooding decoding. Additionally, throughput is doubled and logic complexity reduced of 12%. These advantages are traded-off with error correction performance, thus making the solution attractive only for long codes, as those adopted in the DVB-S2 standard. The "layered decoding" principle is extended to those codes not specifically conceived for this technique. Proposed architectures exhibit complexity savings in the order of 40% for both area and power consumption figures, while implementation loss is smaller than 0.05 dB.
Most modern communication standards employ Orthogonal Frequency Division Multiplexing as part of their physical layer. The core of OFDM is the Fast Fourier Transform and its inverse in charge of symbols (de)modulation. Requirements on throughput and energy efficiency call for FFT hardware implementation, while ubiquity of FFT suggests the design of parametric, re-configurable and re-usable IP hardware macrocells. In this context, this thesis describes an FFT/IFFT core compiler particularly suited for implementation of OFDM communication systems. The tool employs an accuracy-driven configuration engine which automatically profiles the internal arithmetic and generates a core with minimum operands bit-width and thus minimum circuit complexity. The engine performs a closed-loop optimization over three different internal arithmetic models (fixed-point, block floating-point and convergent block floating-point) using the numerical accuracy budget given by the user as a reference point. The flexibility and re-usability of the proposed macrocell are illustrated through several case studies which encompass all current state-of-the-art OFDM communications standards (WLAN, WMAN, xDSL, DVB-T/H, DAB and UWB). Implementations results are presented for two deep sub-micron standard-cells libraries (65 and 90 nm) and commercially available FPGA devices. Compared with other FFT core compilers, the proposed environment produces macrocells with lower circuit complexity and same system level performance (throughput, transform size and numerical accuracy).
The final part of this dissertation focuses on the Network-on-Chip design paradigm whose goal is building scalable communication infrastructures connecting hundreds of core. A low-complexity link architecture for mesochronous on-chip communication is discussed. The link enables skew constraint looseness in the clock tree synthesis, frequency speed-up, power consumption reduction and faster back-end turnarounds. The proposed architecture reaches a maximum clock frequency of 1 GHz on 65 nm low-leakage CMOS standard-cells library. In a complex test case with a full-blown NoC infrastructure, the link overhead is only 3% of chip area and 0.5% of leakage power consumption.
Finally, a new methodology, named metacoding, is proposed. Metacoding generates correct-by-construction technology independent RTL codebases for NoC building blocks. The RTL coding phase is abstracted and modeled with an Object Oriented framework, integrated within a commercial tool for IP packaging (Synopsys CoreTools suite). Compared with traditional coding styles based on pre-processor directives, metacoding produces 65% smaller codebases and reduces the configurations to verify up to three orders of magnitude
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