408 research outputs found
Rapid structural characterization of human antibody-antigen complexes through experimentally validated computational docking.
No full textmissin
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
Altered brain function and structure in a transgenic mouse which overexpress MTH1 hydrolase following an oxidative stimulus by rs-fMRI and DTI
No full textAltered brain function and structure in a transgenic mouse which overexpress MTH1 hydrolase following an oxidative stimulus by rs-fMRI and DTI
Synopsis Oxidative stress is involved in the pathogenesis of cancer, neurodegeneration and aging. hMTH1 is a hydrolase able to protect cells by oxidative damage. Overexpression of hMTH1 in transgenic mice confers significant protection against oxidative damage. Our study showed alterations in the brain networks of hMTH1-Tg mice with respect to their controls. The chronical exposure to an oxidant agent (Paraquat, most widely used herbicide) causes differences in the brain function (measured by rs-fMRI) and structure (measured by DTI) of transgenic mice.
Summary of Main Findings Overexpression of hMTH1 in transgenic mice confers protection against oxidative damage. We detected alterations in brain function and structure of hMTH1-Tg mice before and after a chronic exposure to an oxidant agent.
Introduction The role of the oxidative stress is well known in the pathogenesis of cancer, neurodegeneration and aging. The Human MutT homologue (hMTH1) is a hydrolase able to protect nucleic acids from oxidative damage, by avoiding the incorporation of oxidized precursors in nuclear and mitochondrial DNA and RNA. Interestingly, transgenic mice, which overexpress the human MTH1 gene (hMTH1‐Tg) are protected from neurodegeneration and motor impairment1 and are characterized by a decreased oxidative DNA damage, a better mitochondrial functionality, a prolonged life-span and an enhanced exploratory behavior2.
Aims of this study were to understand if the over-expression of hMTH1 is able to counteract the effects of a chronic exposure to an oxidant agent like the pesticide Paraquat.
Methods Male C57bl6 mice 5 month-old, wild-type (wt, n=8) and hMTH1-Tg (n=8), were analysed by rs-fMRI and DTI before, soon (acute phase) and one month (late phase) after a chronic treatment with Paraquat CL tetrahydrate (5 doses, 10 mg/kg i.p. on alternate days). Experiments were performed on a Pharmascan Bruker (Ettlingen, DE) system operating at 7T equipped with a cryo-probe.
Mouse brain resting state fMRI exploiting the BOLD effect was studied by using a multi slice axial T2* EPI sequence (TR/TE=1000/13.77 ms, segments 2, bandwidth 298972 Hz, matrix 128 x 96, FOV = 20x20 mm,900 temporal points). Seed-based resting state fMRI connectivity maps for the two group of animals were generated as described in 3. In short, first voxel-wise correlation maps were obtained corresponding to a given seed (hippocampus and the pre-frontal cortex (PFC) in both hemispheres) for every session of every mouse. Then z-scores of connectivity are obtained from correlation values across all the sessions to compute significant connections at every voxel. This step is performed through a t-test in which the null hypothesis is that the connectivity is the same as a baseline value corresponding to the mean connectivity in the whole brain.
In the DTI study an EPI sequence with addition of the Stejskal-Tanner diffusion gradients was used. Diffusion gradients were applied along 30 spatial directions. Intensity, duration and diffusion time were set to 62.8 G/cm, 2.5 ms and 8.4 ms respectively, given a b-value of 1200 s/mm2. A field of view of 20 × 20 mm2 was sampled on a 128 × 128 cartesian grid. Multi-slice DT images were acquired (15 slices of 0.7 mm thickness) in the axial plane and TR/TE = 2000/18.75 ms. Using Paravision 360 software (Bruker), diffusivity values (fractional anisotropy, FA and mean diffusivity, MD) were derived from the tensor with a manual delineation of the regions of interest (Hip and PFC) on the FA and MD maps.
T-test and repeated ANOVA measurements were used for statistical comparisons (significance at p<0.05).
Results
The basic finding in a typical connectivity study is that in resting subjects, spontaneous, slow (<0.1 Hz) fluctuations of the blood oxygen level dependent (BOLD) signal are temporally coherent within widely distributed functional networks. Our preliminary seed-based analysis found differences in the functional maps of networks between the wt and the hMTH1-Tg mice at baseline and after exposure to the antioxidant drug.
Specifically, hippocampus (HIP) of the hMTH1-Tg mice shows diffuse increased connectivity with the cortex (mainly the auditory and somatosensory cortex) and the pre-frontal cortex (PFC) shows reduced connectivity with ventral subiculum region (See Figure 1A-B), which is the main subregion controlling the output connections from the HIP. It’s role in the mediation of hippocampal-cortical interaction is under investigation4. These results reveal different functional networks in hMTH1-tg compared to the wt mice.
In the acute phase, we observed that differences in the value of connectivity with the HIP were spread all over the brain in both wt and hMTH1-tg. As an example, for the seed positioned in the PFC we detected differences in the reduction of the connectivity of hMTH1-Tg mice in ipsi- and contra-lateral HIP and other subcortical regions (Figure 1C).
DTI analysis reveals structural differences, a trend of increase in FA in the PFC of the hMTH1-Tg mice compared to wt (see Figure 2). After the exposure to Paraquat we also observed an increase of FA together with a reduction of MD in the HIP of hMTH1-tg mice but not of the wt mice. No significant alteration was induced in the PFC showing a lower vulnerability of this bran region to the oxidant agent.
Analysis on other relevant brain regions are currently in progress.
Discussion and Conclusion Taken together these results showed a region-dependent brain sensitivity of the transgenic mice to paraquat exposure, with HIP as the most involved area. Even if these are still preliminary results and we cannot still interpret the biological and functional significance of the detected differences, we show that our study could lead to clarify the role of oxidative damage on brain function and structure. In particular, given the pivotal role of mitochondria in brain metabolism and function, we can hypothesize that the structural and functional differences between hMTH1-Tg and wt could be linked to a diverse modulation of mitochondrial health and functionality.
References
1. De Luca G et al PLoS Genet 2008;4(11):e1000266.
2. De Luca G et al Aging Cell 2013;12(4):695-705.
3. Canese R et al Psychopharmacology (2015) 232:75–89.
4. Yu N, Song H et al, Neurosci Bull.202
A discrete trinomial model for the birth and death of stock financial bubbles
No full textThe present work proposes a novel way to model the dynamic of financial bubbles. In particular we exploit the so called trinomial tree technique, which is mainly inspired by the typical market order book (MOB) structure. According to the typical MOB rules, we exploit a bottom-up approach to derive the relevant generator process for the financial quantities characterizing the market we are considering. Our proposal pays attention in considering the real world changes in probability levels characterizing the bid-ask preferences, focusing the attention on the market movements. In particular, we show that financial bubbles are originated by these movements which also act amplify their growth
Preliminary Design of a Double Sided Linear Induction Motor as a Catapult for Light Weight Unmanned Aerial Vehicle
No full textIn the last years, the technology of Unmanned Aerial Vehicles (UAVs) has reached a maturity which allows their use in a number of relevant missions. The reduction of the take-off requirements is essential to extend the operating scenario of UAVs. In this paper the authors describe the design of an electromagnetic launch system for a light weigh UAV based on a Double Sided Linear Induction Motor. The length of the launcher and the average thrust force are assigned. The design, based on a multistage configuration, is performed in two steps. In the former, a semi-analytical model of the linear motor is established and the most relevant parameters are chosen. In the latter, the design is iteratively refined by the use of more accurate models based on the Finite Element Method (FEM
Rivisitazioni. Francesco De Sanctis, Storia della letteratura italiana
No full textIl contributo verifica la presenza di un impianto ideale simile a quello che anima la Storia della letteratura italiana di Francesco De Sanctis nella storiografia letteraria coeva, ed esamina l’influenza esercitata su quella successiva dal paradigma morale di cui quest’opera è portatrice. Si sofferma sulla “classicità” dell’opera, sugli aspetti "romanzeschi" della scrittura desanctisiana, sulla presenza dell’idea di policentrismo, su
alcuni modelli e schemi presenti nel giudizio critico di De Sanctis, quali il
gradiente di realismo degli autori e il loro ruolo di precorritori dell’idea nazionale e dell’unità.The author analyzes the presence in coeval literary historiography of an ideal structure similar to the Storia della letteratura italiana by Francesco De Sanctis, examining the
influence of its moral paradigm on later historiography. He dwells upon the “classicism” of the work, the novelistic aspects of the story writing, the problem of the national unity and the presence of the idea of polycentrism, some models and schemes used by De Sanctis to evaluate the authors, such as their level of realism and their role as forerunners of the idea of nation and of the unity
Altered brain connectivity in a transgenic mouse which over-express human hydrolase hMTH1 following an oxidative stimulus: a rs-fMRI and DTI study
No full textAltered brain connectivity in a transgenic mouse which over-express human hydrolase hMTH1 following an oxidative stimulus: a rs-fMRI and DTI study
Introduction The role of the oxidative stress in the pathogenesis of neurodegeneration is well known. The Human MutT homologue (hMTH1) is a hydrolase able to protect nucleic acids from oxidative damage. Interestingly, transgenic mice which overexpress the human MTH1 gene (hMTH1‐Tg) are protected from neurodegeneration and motor impairment.
Aims To understand if the over-expression of hMTH1 is able to counteract the effects of a chronic exposure to an oxidant, like Paraquat.
Methods Male C57bl6 mice, wild-type and hMTH1-Tg, were analysed by rs-fMRI and DTI before and after a chronic treatment with Paraquat. Experiments were performed on a Pharmascan Bruker (Ettlingen, DE) system operating at 7T equipped with a cryo-probe.
Mouse brain resting state fMRI was studied with seed-based analysis. In the DTI study an EPI sequence with 30 direction gradient was used. The diffusivity values (fractional anisotropy, FA and mean diffusivity, MD) were derived from the tensor.
Results Our preliminary seed-based analysis shows differences in the functional networks of the wt and the hMTH1-Tg mice after exposure to the oxidant compound. DTI analysis reveals region specific alterations of FA and MD which differ in the two group of animals after Paraquat exposure. Analysis in other relevant brain areas are in progress.
Discussion and Conclusion Taken together these results show a diverse brain vulnerability of the transgenic mice to the Paraquat exposure, compared to wt and help to deepen insights into the possible mechanisms of action of the hMTH1 over-expression on brain function and structure
Resting state functional MRI and DTI reveal alteration in brain connectivity in a transgenic mouse which over-express human hydrolase hMTH1 following an oxidative stimulus
No full textResting state functional MRI and DTI reveal alteration in brain connectivity in a transgenic mouse which over-express human hydrolase hMTH1 following an oxidative stimulus
Introduction The role of the oxidative stress in the pathogenesis of neurodegeneration is well known. The Human MutT homologue (hMTH1) is a hydrolase able to protect nucleic acids from oxidative damage. Interestingly, transgenic mice which overexpress the human MTH1 gene (hMTH1‐Tg) are protected from neurodegeneration and motor impairment.
Aims To understand if the over-expression of hMTH1 is able to counteract the effects of a chronic exposure to an oxidant, like Paraquat.
Methods Male C57bl6 mice, wild-type and hMTH1-Tg, were analysed by rs-fMRI and DTI before and after a chronic treatment with Paraquat. Experiments were performed on a Pharmascan Bruker (Ettlingen, DE) system operating at 7T equipped with a cryo-probe.
Mouse brain resting state fMRI was studied with seed-based analysis. In the DTI study an EPI sequence with 30 direction gradient was used. The diffusivity values (fractional anisotropy, FA and mean diffusivity, MD) were derived from the tensor.
Results Our preliminary seed-based analysis shows differences in the functional networks of the wt and the hMTH1-Tg mice after exposure to the oxidant compound. DTI analysis reveals region specific alterations of FA and MD which differ in the two group of animals after Paraquat exposure. Analysis in other relevant brain areas are in progress.
Discussion and Conclusion Taken together these results show a diverse brain vulnerability of the transgenic mice to the Paraquat exposure, compared to wt and help to deepen insights into the possible mechanisms of action of the hMTH1 over-expression on brain function and structure
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