2,567 research outputs found

    Purification, characterization and molecular cloning of the major chitinase from Tenebrio molitor larval midgut

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    Insect chitinases are involved in degradation of chitin from the exoskeleton cuticle or from midgut peritrophic membrane during molts. cDNAs coding for insect cuticular and gut chitinases were cloned, but only chitinases from moulting fluid were purified and characterized. In this study the major digestive chitinase from T. molitor midgut (TmChi) was purified to homogeneity, characterized and sequenced after cDNA cloning. TmChi is secreted by midgut epithelial cells, has a molecular weight of 44 kDa and is unstable in the presence of midgut proteinases. TmChi shows strong substrate inhibition when acting on umbelliferyl-derivatives of chitobio- and chitotriosaccharides, but has normal Michaelis kinetics with the N-acetylglucosamine derivative as substrate. TmChi has very low activity against colloidal chitin, but effectively converts oligosaccharides to shorter fragments. The best substrate for TmChi is chitopentaose, with highest kcat/KM value. Sequence analysis and chemical modification experiments showed that the TmChi active site contains carboxylic groups and a tryptophane, which are known to be important for catalysis in family 18 chitinases. Modification with p-hidroximercuribenzoate of a cysteine residue, which is exposed after substrate binding, leads to complete inactivation of the enzyme. TmChi mRNA encodes a signal peptide plus a protein with 37 kDa and high similarity with other insect chitinases from family 18. Surprisingly, this gene does not encode the C-terminal Ser-Thr-rich connector and chitin-binding domain normally present in chitinases. The special features of TmChi probably result from its adaptation to digest chitin-rich food without damaging the peritrophic membrane. © 2006 Elsevier Ltd. All rights reserved

    Ensemble Sales Forecasting Study in Semiconductor Industry

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    Sales forecasting plays a prominent role in business planning and business strategy. The value and importance of advance information is a cornerstone of planning activity, and a well-set forecast goal can guide sale-force more efficiently. In this paper CPU sales forecasting of Intel Corporation, a multinational semiconductor industry, was considered. Past sale, future booking, exchange rates, Gross domestic product (GDP) forecasting, seasonality and other indicators were innovatively incorporated into the quantitative modeling. Benefit from the recent advances in computation power and software development, millions of models built upon multiple regressions, time series analysis, random forest and boosting tree were executed in parallel. The models with smaller validation errors were selected to form the ensemble model. To better capture the distinct characteristics, forecasting models were implemented at lead time and lines of business level. The moving windows validation process automatically selected the models which closely represent current market condition. The weekly cadence forecasting schema allowed the model to response effectively to market fluctuation. Generic variable importance analysis was also developed to increase the model interpretability. Rather than assuming fixed distribution, this non-parametric permutation variable importance analysis provided a general framework across methods to evaluate the variable importance. This variable importance framework can further extend to classification problem by modifying the mean absolute percentage error(MAPE) into misclassify error. Please find the demo code at : https://github.com/qx0731/ensemble_forecast_methodsComment: 14 pages, Industrial Conference on Data Mining 2017 (ICDM 2017

    Therapeutic strategies for IVD regeneration through hyaluronan/SDF-1-based hydrogel and intravenous administration of MSCs

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    Intervertebral disc (IVD) degeneration involves a complex cascade of events, including degradation of the native extracellular matrix, loss of water content, and decreased cell numbers. Cell recruitment strategies for the IVD have been increasingly explored, aiming to recruit either endogenous or transplanted cells. This study evaluates the IVD therapeutic potential of a chemoattractant delivery system (HAPSDF5) that combines a hyaluronan-based thermoreversible hydrogel (HAP) and the chemokine stromal cell derived factor-1 (SDF-1). HAPSDF5 was injected into the IVD and was combined with an intravenous injection of mesenchymal stem/stromal cells (MSCs) in a pre-clinical in vivo IVD lesion model. The local and systemic effects were evaluated two weeks after treatment. The hydrogel by itself (HAP) did not elicit any adverse effect, showing potential to be administrated by intradiscal injection. HAPSDF5 induced higher cell numbers, but no evidence of IVD regeneration was observed. MSCs systemic injection seemed to exert a role in IVD regeneration to some extent through a paracrine effect, but no synergies were observed when HAPSDF5 was combined with MSCs. Overall, this study shows that although the injection of chemoattractant hydrogels and MSC recruitment are feasible approaches for IVD, IVD regeneration using this strategy needs to be further explored before successful clinical translation.Funding: This research was funded by Portuguese funds through FCT-Fundação para a Ciência e a Tecnologia (IUD/BIM/04293/2019) and by EUROSPINE TRF (2017_05)

    Outdoor solutions for the seasonal concentration of tourism demand in northern portugal: an integrated approach based on the gini index

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    Measures that address the seasonality, one of the identified overtourism direct causes, allow making a critical reflection on the application of control policies and monitoring regional measures crucial on a sector with such importance at the regional development analysis. The measures should stimulate or reduce tourism demand during low or peak seasons, respectively, generating a better distribution of tourism flows and eliminating potential overtourism situations. Therefore, this chapter focuses on the development of a Gini Index to analyse the distribution of the seasonality in northern Portugal and through it control current public measures in practice and suggest the implementation of different and more effective policy measures. For instance, the ones that make a clear bet on outdoor tourism activities. It will be used in the Gini Index, by the tourists? market of origin measured by the overnight stays in hotel establishments. The results showed the high seasonal concentration of tourist flows.691D-6753-BE59 | Manuel Jos? Serra da Fonsecainfo:eu-repo/semantics/publishedVersio

    Polyvalent horse F(Ab`)2 snake antivenom: Development of process to produce polyvalent horse F(Ab`)2 antibodies anti-african snake venom

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    A method to obtain polyvalent anti-Bitis and polyvalent-anti-Naja antibodies was developed by immunizing horses with B. arietans, B. nasicornis, B. rhinoceros, N. melanoleuca and N. mossambicacrude venoms. Antibody production was followed by the ELISA method during the immunization procedure. Once the desired anti-venom antibody titers were attained, horses were bled and the immunoglobulins were separated from the sera by (NH4)2SO4 precipitation, cleaved with pepsin and filtered through a 30 kDa ultrafiltration membrane. F(ab´)2 fragments were further purified by Q-Fast Flow chromatography, concentrated by molecular ultrafiltration and sterilized by filtration through 0.22 m membranes. The resulting F(ab´)2 preparations were rich in intact L and in pieces of H IgG(T) chains, as demonstrated by electrophoresis and Western blot and exhibited high antibody titers, as assayed by the ELISA method. In addition, the preparations possess a significant capacity to neutralize the lethality of venoms, as estimated by ED50 determination in mouse assay and are free of toxic substances, pyrogen and bacterial or fungal contaminations

    Effect of band anisotropy on electronic structure of PbS, PbSe, and PbTe quantum dots

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    We have calculated the electronic structure of spherical PbS, PbSe, and PbTe quantum dots using a four-band envelope-function formalism that accounts for band anisotropy. By comparing our results with an analytical calculation that assumes a spherical approximation of the (k) over right arrow.(p) over right arrow Hamiltonian, we show that the effects of band anisotropy are more pronounced for the excited states and increase with the confinement. We also show how the same technique can be applied to ellipsoidal quantum dots.62117357736

    The use of a geographic information system to increase outdoor tourism

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    Purpose: Outdoor tourism is a growing segment that still requires data for planning and management. Aimed to present the potential of the Geographic Information System (GIS) to improve outdoor tourism in the North of Portugal. To achieve this purpose, a case study was conducted on developing a Web-GIS in Northern Portugal. Methodology: Four steps were followed to develop the GIS tool with information about outdoor tourism in the North of Portugal. In the first step, municipalities in the North of Portugal sent information about outdoor activities. In the second step, the data were georeferenced and associated. In the last step, a Web-GIS was developed. Findings: The development of tools is an important source of support for tourism. This study identified that a tool such as the GIS could support a destination's decision-making and promotional processes, besides providing detailed information to the tourist and facilitating travel planning. Practical implications: GIS provides effective planning of outdoor tourism, once this tool allows an effective search of the tourist offer and, from the tourist's perspective, relevant suggestions of visits according to their location are presented, facilitating their experience in the region. Originality: Several studies relate to GIS and tourism, but there is still a gap in specific studies on outdoor activities. So, this study presents the importance of GIS to improve outdoor tourism in the North region of Portugal. Understanding this importance is essential in planning and managing tourism, helping further policymaking and marketing strategies.B913-0565-0908 | Elvira VieiraN/

    Productivity measurement: the case of nature tourism firms in Portugal

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    Productivity measurement in the tourism sector has been raising increasing interest among researchers and is recognised as an important indicator for understanding the strengths and weaknesses of the sector and for enhancing its spillover effects on the economy. However, studies for Portugal and the particular activities included in the set of nature tourism activities are scarce. To overcome this research gap, this paper calculates the labour productivity and total factor productivity (TFP) measures of nature tourism firms to compare firms? productivity performance across NUTS II regions in mainland Portugal during 2014?2017. Using data from SABI, Quadros do Pessoal, INE and the National Tourism Registry, the sample consists of 369 firms, representing 55% of firms operating in nature tourism in the mainland. Results show that the levels of TFP, unlike to labour productivity, are uneven over time and space. In 2015, a year of change in the business cycle, all regions experienced a negative increase in TFP except the Metropolitan Region of Lisbon, which seems to indicate that nature tourism in most of the country is less resilient to external economic shocks, performing better in periods of prosperity. Labour productivity growth does not present, in general, consistently positive results.B913-0565-0908 | Elvira Vieirainfo:eu-repo/semantics/publishedVersio

    Cytological analysis of hybrids among triticales and trigopiros

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    We studied three different tricepiros: (Don Santiago x Don Noé), (Cumé x Horovitz) and (Cumé x Don Noé). The tricepiro (Don Santiago x Don Noé) was obtained by crossing the triticale Don Santiago INTA (AABBRR, 2n = 6x = 42) with the trigopiro Don Noé INTA (AABBDDJJ, 2n = 8x = 56). The number of chromosomes for the F1 was 2n = 49, the most frequent meiotic configuration being 14 bivalents and 21 univalents. The univalents were situated in the periphery of the equatorial plane, whereas the bivalents were located in the central zone. The chromatids in some of the univalents split when bivalents underwent reductional division in anaphase I. There were few laggard chromosomes or chromatids at this phase. The number of chromosomes (2n = 48-58) was high and variable, and the number of bivalents per cell (18-23) also high in F 3 individuals. In all F 8 tricepiros (Don Santiago x Don Noé), F 12 tricepiros (Cumé x Horovitz) and F 12 tricepiros (Cumé x Don Noé), the number of chromosomes (2n = 42) was the same, these retaining the rye genome, as demonstrated by GISH and FISH. These new synthesized allopolyploids constitute interesting models for investigating the evolutionary changes responsible for diploidization, and the chromosomal and genomic re-ordering that cannot be revealed in natural allopolyploids
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