3,020 research outputs found
Esperienze nell’applicazione di tecniche “compression pre-cracking” per prove di propagazione frattura
No full textConsiderando tecniche di progettazione moderne quali la “Damage Tolerance”, la caratterizzazione delle curve di propagazione è uno degli elementi fondamentali, per la valutazione e la progettazione dell’integrità strutturale dei componenti in servizio, insieme alla performance dei controlli non distruttivi e alla determinazione dei carichi di esercizio. La zona della soglia di propagazione risulta poi particolarmente critica in quanto è lecito pensare che la maggior parte della vita di un componente avvenga nel suo ambito.
Recentemente, è stato però dimostrato che le metodologie tradizionali per la determinazione della soglia di propagazione, quali il “K-decreasing” e il “Kmax=const.”, influenzano il risultato in maniera non conservativa, ovvero possono produrre soglie di propagazione più alte di quelle naturali del materiale. E’ quindi stata proposta una metodologia innovativa basata sulla pre-criccatura in compressione. Tale tecnica, data la sua recente introduzione, è stata finora applicata a pochi casi applicativi. I materiali considerati ad oggi sono le leghe di alluminio, le leghe di titanio e gli acciai ad alta resistenza sollecitati mediante geometrie M(T) e C(T) e a rapporti di ciclo positivi.
La presente memoria si è quindi incentrata nell’applicazione della metodologia innovativa all’acciaio dolce strutturale A1N (tipicamente utilizzato per produrre assili ferroviari) in forma di provini SE(B) sollecitati da un ampio raggio di rapporti di ciclo tra R=-2 e R=0.85
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,
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
Analysis of synaptic-like microvesicle exocytosis of B-cells using a live imaging technique.
No full textPancreatic β-cells play central roles in blood glucose homeostasis. Beside insulin, these cells release neurotransmitters and other signaling molecules stored in synaptic-like microvesicles (SLMVs). We monitored SLMV exocytosis by transfecting a synaptophysin-pHluorin construct and by visualizing the cells by Total Internal Reflection Fluorescence (TIRF) microscopy. SLMV fusion was elicited by 20 mM glucose and by depolarizing K(+) concentrations with kinetics comparable to insulin secretion. SLMV exocytosis was prevented by Tetanus and Botulinum-C neurotoxins indicating that the fusion machinery of these organelles includes VAMP-2/-3 and Syntaxin-1, respectively. Sequential visualization of SLMVs by TIRF and epifluorescence microscopy showed that after fusion the vesicle components are rapidly internalized and the organelles re-acidified. Analysis of single fusion episodes revealed the existence of two categories of events. While under basal conditions transient fusion events prevailed, long-lasting episodes were more frequent upon secretagogue exposure. Our observations unveiled similarities between the mechanism of exocytosis of insulin granules and SLMVs. Thus, diabetic conditions characterized by defective insulin secretion are most probably associated also with inappropriate release of molecules stored in SLMVs. The assessment of the contribution of SLMV exocytosis to the manifestation of the disease will be facilitated by the use of the imaging approach described in this study
Bariatric surgery and new-onset substance use disorders: a systematic review and meta-analysis
No full text: Increasing evidence suggests that bariatric surgery (BS) patients are at risk for substance abuse disorders (SUD). The purpose of this systematic review and meta-analysis was to determine the relationship between BS and the development of new-onset substance abuse disorder (SUDNO) in bariatric patients. On October 31, 2023, we reviewed the scientific literature following PRISMA guidelines. A total of 3242 studies were analyzed, 7 met the inclusion criteria. The pooled incidence of SUDNO was 4.28%. Patients' characteristics associated with SUDNO included preoperative mental disorders, high pre-BS BMI, and public health insurance. Surgical factors associated with new SUDNOs included severe complications in the peri- or postoperative period. The occurrence of SUDNOs is a non-negligeable complication after BS. Predisposing factors may be identified and preventive actions undertaken
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}
Conspiracy beliefs, COVID-19 vaccine uptake and adherence to public health interventions during the pandemic in Europe
No full textBackground: Conspiracy beliefs can be a major hindrance causing a lack of compliance with public health measures, including vaccination. We examined the relationship between individual attitudes, socio-demographic factors, conspiracy beliefs, COVID-19 vaccine hesitancy and preferences about pandemic policies in Europe. Methods: We used data from the 10th round of the European Social Survey, conducted in 2021-22 in 17 European countries. Both a conspiracy index and a personal attitude index for each participant were built by using a Latent Class Analysis model. Then, we used a multilevel regression model to investigate the relationship between a personal attitudes index, socio-demographic factors and country of residence, and a conspiracy index. We descriptively analyse the relationship between the conspiracy index and four main items related to COVID-19. Results: We found that a higher probability of believing in conspiracy theories was associated with male gender, middle age, lower levels of education, unemployment, lower levels of trust and satisfaction and right-wing political orientation. The country of residence was a contextual factor, with eastern European countries having higher levels of conspiracy beliefs. Individuals who expressed conspiracy beliefs had lower COVID-19 vaccine uptake, were less satisfied with the way health services coped with the pandemic and less supportive of governmental restrictions. Conclusions: This study provides valuable insights into the factors associated with conspiracy beliefs and their potential impact on public health. The findings highlight the need for effective strategies to address the underlying factors driving conspiracy beliefs, reduce vaccine hesitancy and promote acceptance of public health interventions
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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