286 research outputs found

    Asymptotic expansion for some local volatility models arising in finance

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    In this paper we study the small noise asymptotic expansions for certain classes of local volatility models arising in finance. We provide explicit expressions for the involved coefficients as well as accurate estimates on the remainders. Moreover, we perform a detailed numerical analysis, with accuracy comparisons, of the obtained results by mean of the standard Monte Carlo technique as well as exploiting the polynomial Chaos Expansion approach

    Asymptotic expansion for some local volatility models arising in finance

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    In this paper, we study the small noise asymptotic expansions for certain classes of local volatility models arising in finance. We provide explicit expressions for the involved coefficients as well as accurate estimates on the remainders. Moreover, we perform a detailed numerical analysis, with accuracy comparisons, of the obtained results by means of the standard Monte Carlo technique as well as exploiting the Polynomial Chaos Expansion approach

    High performance bilayer-graphene Terahertz detectors

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    We report bilayer-graphene field effect transistors operating as THz broadband photodetectors based on plasma-waves excitation. By employing wide-gate geometries or buried gate configurations, we achieve a responsivity ∼1.2V/W(1.3mA/W)\sim 1.2V/W (1.3 mA/W) and a noise equivalent power ∼2×10−9W/Hz−1/2\sim 2\times 10^{-9} W/Hz^{-1/2} in the 0.29-0.38 THz range, in photovoltage and photocurrent mode. The potential of this technology for scalability to higher frequencies and the development of flexible devices makes our approach competitive for a future generation of THz detection systems.Comment: 8 pages, 5 figures. Submitted to Applied Physics Letter

    Willage: A Two-Tiered Peer-to-Peer Resource Sharing Platform for Wireless Mesh Community Networks

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    The success of experiences such as Seattle and Houston Wireless has attracted the attention on the so called wireless mesh community networks. These are wireless multihop networks spontaneously deployed by users willing to share communication resources. Due to the community spirit characterizing such networks, it is likely that users will be willing to share other resources besides communication resources, such as data, images, music, movies, disk quotas for distributed backup, and so on. In other words, it is expected that peer-to-peer applications will be deployed in such type of networks. In this paper we propose Willage, a platform for resource localization in wireless mesh community networks with mobile users. The platform is based on a two-tiered architecture: resources are made available at the lower tier, which is composed of mobile terminals, whereas information on their localization is managed at the upper layer, which is composed of wireless mesh routers. We also introduce Georoy, an algorithm for the efficient retrieval of the information on resource localization based on the Viceroy algorithm. Simulation results show that Willage achieves its goal of enabling efficient and scalable peer-to-peer resource sharing in wireless mesh community networks

    Bilateral Corneal Perforation in a Patient with Chronic Ocular Graft-Versus-Host Disease: A Case Report and Literature Review

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    Graft-versus-host disease (GVHD) is a serious complication that may occur in patients receiving allogeneic hematopoietic stem cell transplant (HSCT). GVHD occurs because of the immunological reaction between the donor’s T cells and the recipient’s antigens; GVHD may develop in different tissues, including the eye. Corneal perforation is an uncommon but vision-threatening manifestation of GVHD. We reported the case of a 65-year-old male patient who developed corneal perforation sequentially in both eyes 3 years after receiving HSCT. Conservative treatment with topical steroids and lubricants, bandage contact lens, and lacrimal punctal occlusion surgery resulted in the successful resolution of the corneal perforation with satisfactory visual recovery in the right eye. Therefore, corneal perforation can occur as the presenting manifestation of ocular GVHD. Regular ophthalmological examinations are recommended after HSCT to enable the early diagnosis of ocular GVHD and prompt treatment initiation

    Pushing Stoichiometries of Lithium-Rich Layered Oxides Beyond Their Limits

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    Lithium-rich layered oxides (LRLOs) are opening unexplored frontiers for high-capacity/high-voltage positive electrodes in Li-ion batteries (LIBs) to meet the challenges of green and safe transportation as well as cheap and sustainable stationary energy storage from renewable sources. LRLOs exploit the extra lithiation provided by the Li1.2TM0.8O2 stoichiometries (TM = a blend of transition metals with a moderate cobalt content) achievable by a layered structure to disclose specific capacities beyond 200-250 mA h g(-1) and working potentials in the 3.4-3.8 V range versus Li. Here, we demonstrate an innovative paradigm to extend the LRLO concept. We have balanced the substitution of cobalt in the transition-metal layer of the lattice with aluminum and lithium, pushing the composition of LRLO to unexplored stoichiometries, that is, Li-1.2(+x)(Mn,Ni,Co,AI)(0.8-x)O2-delta. The fine tuning of the composition of the metal blend results in an optimized layered material, that is, Li1.28Mn0.54Ni0.13Co0.02Al0.03O2-delta, with outstanding electrochemical performance in full LIBs, improved environmental benignity, and reduced manufacturing costs compared to the state-of-the-art

    A model of N-terminal Cyclin T1 based on FRET experiments

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    Human Cyclin T1 is the cyclin partner of kinase CDK9 in the positive transcription elongation factor b (P-TEFb). P-TEFb is recruited by Tat, the transactivator of the human immunodeficiency virus type 1 (HIV-1), to the viral promoter by direct interactions between Tat, Cyclin T1 and thecis-acting transactivation-responsive region (TAR) present at the 5′-end of each viral mRNA. At present, no structural data for Cyclin T1 are available. Here, we build a structural model of an N-terminus portion of Cyclin T1 (aa 27–263) based on the X-ray structure of Cyclin H. The model is compared with site directed mutagenesis data from the literature and validated by fluorescence resonance energy transfer (FRET) using Tat as a probe in living cells. This model provides a first step towards the structural characterization of the CDK9–CycT1–Tat-TAR complex, which is crucial for HIV-1 replication and may constitute a promising target for pharmaceutical intervention

    Monitoring and mapping soil functionality in degraded areas of organic European vineyards

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    Póster presentado en el 11th International Terroir Congress, celebrado en Willamette Valley, Oregon (Estados Unidos) del 10 al 14 de julio de 2016.Soil malfunctioning, caused by an improper land preparation before vine plantation and/or management, is a common problem in European vineyards. Soil malfunctioning can include: reduced contribution of the soil fauna, poor organic matter content, imbalance nutritional status, altered pH, water deficiency, soil compaction and/or scarce oxygenation. To address these problems, ReSolVe, a transnational European research project, aimed at testing the effects of selected agronomic strategies for restoring optimal soil functionality in degraded areas within organic vineyard. The project involves 8 research groups in 6 different EU countries (Italy, Spain, France, Sweden, Slovenia, and Turkey) with experts from several disciplines including soil science, ecology, microbiology, grapevine physiology, viticulture, and biometry. The experimental vineyards are situated in Italy (Chianti hills and Maremma plain, Tuscany), Spain (La Rioja), France (Bordeaux and Languedoc), and Slovenia (Primorska) for winegrapes, and in Turkey (Adana and Mersin) for tablegrapes. Three different restoring strategies have been implemented: (i) compost, (ii) green manure with winter legumes, and (iii) dry mulching with cover crops. These strategies have being tested according to their efficiency to improve i) plant and root growth; and ii) grape yield and quality; optimize iii) the quality of soil ecosystem services; and iv) the terroir effect. The first activity of the project was characterizing and mapping the degraded areas within experimental vineyards. In the work we used non-invasive technologies to characterize soil and plant status. In Spanish and Italian vineyards, the delineation of degraded areas was performed by gamma-ray spectroscopy for topsoil, RGB machine vision for canopy status and thermography for plant water status. Gamma-ray spectroscopy measured continuously the natural gamma-ray emitted from the first 30-40 cm of soil, calculating the contribution of the main radionuclides (40K, 232Th, and 238U). The spectra of gamma-ray were able to provide information about mineralogy, texture, surficial stoniness and carbonates. RGB and thermal cameras were used to assess canopy porosity, leaf area exposure and vine water status of both degraded and non-degraded areas. All soil, canopy and water status parameters were mapped.Peer Reviewe

    725. Correction of Laminin-5-Deficient Junctional Epidermolysis Bullosa by Transplantation of Genetically Modified Epidermal Stem Cells. A Phase-I Clinical Trial

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    Mutations in genes encoding the laminin-5 heterotrimer, a key component of the epidermal-dermal junction, cause junctional epidermolysis bullosa (JEB), a severe and often fatal skin adhesion defect. Epidermal stem cells isolated from patients affected by |[beta]|3 chain-deficient JEB were transduced with a retroviral vector expressing a |[beta]|3 cDNA, and used to generate uniformly transduced cultured skin implants. The transgene was steadily expressed for >160 cell doublings in culture, leading to restoration of normal laminin 5 levels, assembly of functional hemidesmosomes, and full phenotypic correction. Cloning and sequencing of vector integrations showed that <20 stem cells are responsible for long-term maintenance of a transplantable skin culture. A phase-I clinical trial started in October 2005, aimed at proving the safety of the transduction/transplantation procedure, and analyzing persistence of transgene expression and long-term survival of transduced stem cells. The first patient was a 30-yr-old male affected by non-lethal JEB, carrying a null mutation in one LAMB3 allele and a point mutation (E212K) in the other one. The mutation affects the assembly of the laminin-5 heterotrimer, present at residual levels (<5%) in vitro and in vivo. Six genetically modified, cultured epidermal sheets of 100 sq cm were transplanted on both legs after removal of the outer skin layer using a minimally invasive technique. The procedure was well tolerated, and the patient discharged after five days. Engraftment was completed after 10 days, and transplanted skin remained stable on both legs in the absence of blistering or inflammation for the duration of the follow-up (4 months at the time of writing). 3-mm punch biopsies were taken 1 and 3 months after transplantation, and analyzed for vector presence by quantitative PCR and for protein expression by immunohistochemistry. A vector signal compatible with full transduction of the transplanted epidermis was observed at both time points. Synthesis and assembly of normal levels of heterotrimeric laminin-5 and |[alpha]|6|[beta]|4 integrin was observed at the level of the basal lamina in all biopsies, together with the development of a firmly adherent, fully differentiated epidermis. Epidermal stem cells (p64+) were detected in the basal layer of the transplanted skin in normal numbers. These data show that gene therapy of JEB by transplantation of genetically corrected stem cells is feasible, and leads to full phenotypic correction of the adhesion defect in vivo. Safety studies are under way, which include detection or humoral or cytotoxic immune responses against laminin-5, and ex vivo cloning and sequencing of the integrated proviruses
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