298 research outputs found
Convertible subspaces that arise from different numberings of the vertices of a graph
In this paper, we describe subspaces of generalized Hessenberg matrices where the determinant is convertible into the permanent by affixing ± signs. These subspaces can arise from different numberings of the vertices of a graph. With this numbering process, we obtain some well-known sequences of integers. For instance, in the case of a path of length n, we prove that the number of these subspaces is the (n + 1)th Fibonacci number.info:eu-repo/semantics/publishedVersio
Alquimia, Magia e QuĂmica: relato de experiĂŞncia de um projeto de extensĂŁo
Neste artigo Ă© apresentado o relato de experiĂŞncia do projeto de extensĂŁo denominado Divulgação e Popularização da QuĂmica no Centro de Educação em Tempo Integral Verde Vale. O objetivo da atividade foi de explorar o encanto do Dia Das Bruxas abordando-se a alquimia na histĂłria da QuĂmica. Verificou-se que a experimentação na qual se fez uso de leite, corante, detergente e - uma “varinha mágicaӬ- despertou grande entusiasmo possibilitando o despertar do interesse cientĂfico.DOI: http://dx.doi.org/10.35700/ca.2019.ano6n10.p77-84.242
Challenges to Domesticating Native Forage Legumes
If ruminant production from cultivated and natural grasslands is to depend less on petroleum-based products, forage legumes must serve as protein sources. Commercially available legumes for warm-dry climate grasslands are, however, very limited and resources available for developing such legumes are inadequate. Indeterminate flowering and dehiscent seed pods combined with the need for specialized seed harvesting equipment are major impediments (Butler and Muir 2012). Warm climates often present environmental challenges such as poor rainfall distribution, extended dry seasons, temperature extremes and aggressive grass species (Muir et al. 2011). Erosion of indigenous knowledge and replacement with inappropriate land management approaches from moist-temperate regions compound the challenges
The Use of Zidovudine Pharmacophore in Multi-Target-Directed Ligands for AIDS Therapy
The concept of polypharmacology embraces multiple drugs combined in a therapeutic regimen (drug combination or cocktail), fixed dose combinations (FDCs), and a single drug that binds to different targets (multi-target drug). A polypharmacology approach is widely applied in the treatment of acquired immunodeficiency syndrome (AIDS), providing life-saving therapies for millions of people living with HIV. Despite the success in viral load suppression and patient survival of combined antiretroviral therapy (cART), the development of new drugs has become imperative, owing to the emergence of resistant strains and poor adherence to cART. 3′-azido-2′,3′-dideoxythymidine, also known as azidothymidine or zidovudine (AZT), is a widely applied starting scaffold in the search for new compounds, due to its good antiretroviral activity. Through the medicinal chemistry tool of molecular hybridization, AZT has been included in the structure of several compounds allowing for the development of multi-target-directed ligands (MTDLs) as antiretrovirals. This review aims to systematically explore and critically discuss AZT-based compounds as potential MTDLs for the treatment of AIDS. The review findings allowed us to conclude that: (i) AZT hybrids are still worth exploring, as they may provide highly active compounds targeting different steps of the HIV-1 replication cycle; (ii) AZT is a good starting point for the preparation of co-drugs with enhanced cell permeability
Discriminant analysis of pyrrolizidine alkaloid contamination in bee pollen based on near-infrared data from lab-stationary and portable spectrometers
Bee pollen may be contaminated with pyrrolizidine alkaloids (PAs) and their N-oxides (PANOs), which are mainly detected by liquid chromatography coupled to tandem mass spectrometry (LC\u2013MS/MS), even though the use of fast near-infrared (NIR) spectroscopy is an ongoing alternative. Therefore, the main challenge of this study was to assess the feasibility of both a lab-stationary (Foss) and a portable (Polispec) NIR spectrometer in 60 dehydrated bee pollen samples. After an ANOVA-feature selection of the most informative NIR spectral data, canonical discriminant analysis (CDA) was performed to distinguish three quantitative PA/PANO classes (\ub5g/kg): 400, high. According to the LC\u2013MS/MS analysis, 77% of the samples were contaminated with PAs/PANOs and the sum content of the 17 target analytes was higher than 400\ua0\ub5g/kg in 28% of the samples. CDA was carried out on a pool of 18 (Foss) and 22 (Polispec) selected spectral variables and allowed accurate classification of samples from the low class as confirmed by the high values of Matthews correlation coefficient ( 65 0.91) for both NIR spectrometers. Leave-one-out cross-validation highlighted precise recognition of samples characterised by a high PA/PANO content with a low misclassification rate (0.02) as false negatives. The most informative wavelengths were within the 2400\ua0nm regions for Foss and > 1500\ua0nm for Polispec that could be associated with cyclic amines, and epoxide chemical structures of PAs/PANOs. In sum, both lab-stationary and portable NIR systems are reliable and fast techniques for detecting PA/PANO contamination in bee pollen
Design and Evaluation of HTTP Protocol Parsers for IPFIX Measurement
In this paper we analyze HTTP protocol parsers that provide a web traffic visibility to IP flow. Despite extensive work, flow meters generally fall short of performance goals due to extracting application layer data. Constructing effective protocol parser for in-depth analysis is a challenging and error-prone affair. We designed and evaluated several HTTP protocol parsers representing current state-of-the-art approaches used in today's flow meters. We show the packet rates achieved by respective parsers, including the throughput decrease (performance implications of application parser) which is of the utmost importance for high-speed deployments.ÄŚlánek zkoumá syntaktickĂ© analyzátory HTTP protokolu, kterĂ© rozšiĹ™ujĂ sĂĹĄovĂ© toky o informace z webovĂ©ho provozu. VĂ˝poÄŤetnÄ› nároÄŤnĂ© zĂskávánĂ informacĂ z aplikaÄŤnĂ vrstvy má vliv na vĂ˝kon měřicĂch sond a mĹŻĹľe vĂ©st k vĂ˝raznĂ©mu poklesu jejich vĂ˝konu. Tvorba rychlĂ©ho analyzátoru pro hloubkovou analĂ˝zu HTTP protokolu je nároÄŤnĂ˝ proces s ohledem na správnĂ© a vÄŤasnĂ© zpracovánĂ dat ze sĂtÄ›. ÄŚlánek porovnává naši implementaci vybranĂ˝ch metod pro analĂ˝zu HTTP provozu, kterĂ© jsou v souÄŤasnosti pouĹľĂvány v sondách na měřenĂ sĂĹĄovĂ˝ch tokĹŻ. Provedená měřenĂ ukazujĂ mnoĹľstvĂ paketĹŻ, kterĂ© je sonda schopna zpracovat pĹ™i zapnutĂ© analĂ˝ze HTTP a jak toto mnoĹľstvĂ klesá oproti sondám, kterĂ© analĂ˝zu aplikaÄŤnĂch protokolĹŻ neprovádÄ›jĂ. Jedná se o vĂ˝znamnou informaci pro nasazenĂ měřicĂch sond ve vysokorychlostnĂch sĂtĂch
Assessing, quantifying and valuing the ecosystem services of coastal lagoons
The natural conservation of coastal lagoons is important not only for their ecological importance, but also because of the valuable ecosystem services they provide for human welfare and wellbeing. Coastal lagoons are shallow semi-enclosed systems that support important habitats such as wetlands, mangroves, salt-marshes and seagrass meadows, as well as a rich biodiversity. Coastal lagoons are also complex social-ecological systems with ecosystem services that provide livelihoods, wellbeing and welfare to humans. This study assessed, quantified and valued the ecosystem services of 32 coastal lagoons. The main findings of the study are: (i) the definitions of ecosystem services are still not generally accepted; (ii) the quantification of ecosystem services is made in many different ways, using different units; (iii) the evaluation in monetary terms of some ecosystem service is problematic, often relying on non-monetary evaluation methods; (iv) when ecosystem services are valued in monetary terms, this may represent very different human benefits; and, (v) different aspects of climate change, including increasing temperature, sea-level rise and changes in rainfall patterns threaten the valuable ecosystem services of coastal lagoons.DEVOTES project, from the European Union's Seventh Framework Programme for research, technological development and demonstration [308392]; networks and communities of Eurolag; Future Earth Coasts; SCOR; Fundacao para a Ciencia e a Tecnologia (FCT) Investigador Programme [IF/00331/2013]; Fundacao para a Ciencia e a Tecnologia [UID/MAR/04292/2013]; CESAM by FCT/MEC national funds (PIDDAC) [UID/AMB/50017/2013 - POCI-01-0145-FEDER-007638]; FEDER; European Commission, under the 7th Framework Programme through the collaborative research project LAGOONS [283157]; FCT [SFRH/BPD/107823/2015, SFRH/BPD/91494/2012
Acute partial Budd-Chiari syndrome and portal vein thrombosis in cytomegalovirus primary infection: a case report
BACKGROUND: Splanchnic vein thrombosis may complicate inherited thrombotic disorders. Acute cytomegalovirus infection is a rare cause of acquired venous thrombosis in the portal or mesenteric territory, but has never been described extending into a main hepatic vein. CASE PRESENTATION: A 36-year-old immunocompetent woman presented with acute primary cytomegalovirus infection in association with extensive thrombosis in the portal and splenic vein. In addition, a fresh thrombus was evident in the right hepatic vein. A thorough evaluation for a hypercoagulable state was negative. The clinical course, biological evolution, radiological and histological findings were consistent with cytomegalovirus hepatitis complicated by a partial acute Budd-Chiari syndrome and portal thrombosis. Therapeutic anticoagulation was associated with a slow clinical improvement and partial vascular recanalization. CONCLUSION: We described in details a new association between cytomegalovirus infection and acute venous thrombosis both in the portal vein and in the right hepatic vein, realizing a partial Budd-Chiari syndrome. One should be aware that this rare thrombotic event may be complicated by partial venous outflow block
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