Proton Formation in 2+1 Resonance Enhanced Multiphoton Excitation of HCl and HBr via „=0… Rydberg and Ion-Pair States

Molecular beam cooled HCl was state selected by two-photon excitation of the V (1) summation operator(0(+)) [v=9,11-13,15], E (1) summation operator(0(+)) [v=0], and g (3) summation operator(-)(0(+)) [v=0] states through either the Q(0) or Q(1) lines of the respective (1,3) summation operator(0(+))<--<--X (1) summation operator(0(+)) transition. Similarly, HBr was excited to the V (1) summation operator(0(+)) [v=m+3, m+5-m+8], E (1) summation operator(0(+)) [v=0], and H (1) summation operator(0(+)) [v=0] states through the Q(0) or Q(1) lines. Following absorption of a third photon, protons were formed by three different mechanisms and detected using velocity map imaging. (1) H(*)(n=2) was formed in coincidence with (2)P(i) halogen atoms and subsequently ionized. For HCl, photodissociation into H(*)(n=2)+Cl((2)P(12)) was dominant over the formation of Cl((2)P(32)) and was attributed to parallel excitation of the repulsive [(2) (2)Pi4llambda] superexcited (Omega=0) states. For HBr, the Br((2)P(32))Br((2)P(12)) ratio decreases with increasing excitation energy. This indicates that both the [(3) (2)Pi(12)5llambda] and the [B (2) summation operator5llambda] superexcited (Omega=0) states contribute to the formation of H(*)(n=2). (2) For selected intermediate states HCl was found to dissociate into the H(+)+Cl(-) ion pair with over 20% relative yield. A mechanism is proposed by which a bound [A (2) summation operatornlsigma] (1) summation operator(0(+)) superexcited state acts as a gateway state to dissociation into the ion pair. (3) For all intermediate states, protons were formed by dissociation of HX(+)[v(+)] following a parallel, DeltaOmega=0, excitation. The quantum yield for the dissociation process was obtained using previously reported photoionization efficiency data and was found to peak at v(+)=6-7 for HCl and v(+)=12 for HBr. This is consistent with excitation of the repulsive A(2) summation operator(12) and (2) (2)Pi states of HCl(+), and the (3) (2)Pi state of HBr(+). Rotational alignment of the Omega=0(+) intermediate states is evident from the angular distribution of the excited H(*)(n=2) photofragments. This effect has been observed previously and was used here to verify the reliability of the measured spatial anisotropy parameters.

A review of the selective reduction of NOx, with hydrocarbons under lean-burn conditions with non-zeolitic oxide and platinum group metal catalysts

Research on the selective reduction of NOx with hydrocarbons under lean-burn conditions using non-zeolitic oxides and platinum group metal (PGM) catalysts has been critically reviewed. Alumina and silver-promoted alumina catalysts have been described in detail with particular emphasis on an analysis of the various reaction mechanisms that have been put forward in the literature. The influence of the nature of the reducing agent, and the preparation and structure of the catalysts have also been discussed and rationalised for several other oxide systems. It is concluded for non-zeolitic oxides that species that are strongly adsorbed on the surface, such as nitrates/nitrites and acetates, could be key intermediates in the formation of various reduced and oxidised species of nitrogen, the further reaction of which leads eventually to the formation of molecular nitrogen. For the platinum group metal catalysts, the different mechanisms that have been proposed in the literature have been critically assessed. It is concluded that although there is indirect, mainly spectroscopic, evidence for various reaction intermediates on the catalyst surface, it is difficult to confirm that any of these are involved in a critical mechanistic step because of a lack of a direct quantitative correlation between infrared and kinetic measurements. A simple mechanism which involves the dissociation of NO on a reduced metal surface to give N(ads) and O(ads), with subsequent desorption of N-2 and N2O and removal of O(ads) by the reductant can explain many of the results with the platinum group metal catalysts, although an additional contribution from organo-nitro-type species may contribute to the overall NOx reduction activity with these catalysts.

Do development and learning really decrease memory? On similarity and category-based induction in adults and children

In a recently published study, Sloutsky and Fisher [Sloutsky, V. M., & Fisher, A.V. (2004a). When development and learning decrease memory: Evidence against category-based induction in children. Psychological Science, 15, 553-558; Sloutsky, V. M., & Fisher, A. V. (2004b). Induction and categorization in young children: A similarity-based model. Journal of Experimental Psychology: General, 133, 166-188.] demonstrated that children have better memory for the items that they generalise to than do adults. On the basis of this finding, they claim that children and adults use different mechanisms for inductive generalisations;whereas adults focus on shared category membership, children project properties on the basis of perceptual similarity. Sloutsky & Fisher attribute children's enhanced recognition memory to the more detailed processing required by this similarity-based mechanism. In Experiment I we show that children look at the stimulus items for longer than adults. In Experiment 2 we demonstrate that although when given just 250 ms to inspect the items children remain capable of making accurate inferences, their subsequent memory for those items decreases significantly. These findings suggest that there are no necessary conclusions to be drawn from Sloutsky & Fisher's results about developmental differences in generalisation strategy. (C) 2007 Elsevier B.V. All rights reserved.

Evidence for a Direct and Functional Interaction between the Regulators of G Protein Signaling-2 and Phosphorylated C Terminus of Cholecystokinin-2 Receptor

Signaling of G protein-coupled receptors (GPCRs) is regulated by different mechanisms. One of these involves regulators of G protein signaling (RGS), which are diverse and multifunctional proteins that bind to active G alpha subunits of G proteins and act as GTPase-activating proteins. Little is known about the molecular mechanisms that govern the selective use of RGS proteins in living cells. We first demonstrated that CCK2R-mediated inositol phosphate production, known to be G(q-)dependent, is more sensitive to RGS2 than to RGS4 and is insensitive to RGS8. Both basal and agonist-stimulated activities of the CCK2R are regulated by RGS2. By combining biochemical functional, and in silico structural approaches, we demonstrate that a direct and functional interaction occurs between RGS2 and agonist-stimulated cholecystokinin receptor-2 (CCK2R) and identified the precise residues involved: phosphorylated Ser434 and Thr439 located in the C-terminal tail of CCK2R and Lys62, Lys63, and Gln67, located in the N-terminal domain of RGS2. These findings confirm previous reports that RGS proteins can interact with GPCRs to modulate their signaling and provide a molecular basis for RGS2 recognition by the CCK2R.

Haloalkane degradation and assimilation by Rhodococcus rhodochrous NCIMB -13064

The bacterium Rhodococcus rhodochrous NCIMB 13064, isolated from an industrial site, could use a wide range of 1-haloalkanes as sole carbon source but apparently utilized several different mechanisms simultaneously for assimilation of substrate. Catabolism of 1-chlorobutane occurred mainly by attack at the C-1 atom by a hydrolytic dehalogenase with the formation of butanol which was metabolized via butyric acid. The detection of small amounts of gamma-butyrolactone in the medium suggested that some oxygenase attack at C-4 also occurred, leading to the formation of 4-chlorobutyric acid which subsequently lactonized chemically to gamma-butyrolactone. Although 1-chlorobutane-grown cells exhibited little dehalogenase activity on 1-chloroalkanes with chain lengths above C-10, the organism utilized such compounds as growth substrates with the release of chloride. Concomitantly, gamma-butyrolactone accumulated to 1 mM in the culture medium with 1-chlorohexadecane as substrate. Traces of 4-hydroxybutyric acid were also detected. It is suggested that attack on the long-chain chloroalkane is initiated by an oxygenase at the non-halogenated end of the molecule leading to the formation of an omega-chlorofatty acid. This is degraded by beta-oxidation to 4-chlorobutyric acid which is chemically lactonized to gamma-butyrolactone which is only slowly further catabolized via 4-hydroxybutyric acid and succinic acid. However, release of chloride into the medium during growth on long-chain chloroalkanes was insufficient to account for all the halogen present in the substrate. Analysis of the fatty acid composition of 1-chlorohexadecane-grown cells indicated that chlorofatty acids comprised 75% of the total fatty acid content with C-14:0, C-16:0, C-16:1, and C-18:1 acids predominating. Thus the incorporation of 16-chlorohexadecanoic acid, the product of oxygenase attack directly into cellular lipid represents a third route of chloroalkane assimilation. This pathway accounts at least in part for the incomplete mineralization of long-chain chloroalkane substrates. This is the first report of the coexistence of a dehalogenase and the ability to incorporate long-chain haloalkanes into the lipid fraction within a single organism and raises important questions regarding the biological treatment of haloalkane containing effluents.

Exploratory Space-Time Analyses of Rift Valley Fever in South Africa in 2008-2011

Background: Rift Valley fever (RVF) is a zoonotic arbovirosis for which the primary hosts are domestic livestock (cattle, sheep and goats). RVF was first described in South Africa in 1950-1951. Mechanisms for short and long distance transmission have been hypothesised, but there is little supporting evidence. Here we describe RVF occurrence and spatial distribution in South Africa in 2008-11, and investigate the presence of a contagious process in order to generate hypotheses on the different mechanisms of transmission. Methodology/Principal Findings: A total of 658 cases were extracted from World Animal Health Information Database. Descriptive statistics, epidemic curves and maps were produced. The space-time K-function was used to test for evidence of space-time interaction. Five RVF outbreak waves (one in 2008, two in 2009, one in 2010 and one in 2011) of varying duration, location and size were reported. About 70% of cases (n = 471) occurred in 2010, when the epidemic was almost country-wide. No strong evidence of space-time interaction was found for 2008 or the second wave in 2009. In the first wave of 2009, a significant space-time interaction was detected for up to one month and over 40 km. In 2010 and 2011 a significant intense, short and localised space-time interaction (up to 3 days and 15 km) was detected, followed by one of lower intensity (up to 2 weeks and 35 to 90 km). Conclusions/Significance: The description of the spatiotemporal patterns of RVF in South Africa between 2008 and 2011 supports the hypothesis that during an epidemic, disease spread may be supported by factors other than active vector dispersal. Limitations of under-reporting and space-time K-function properties are discussed. Further spatial analyses and data are required to explain factors and mechanisms driving RVF spread. © 2012 Métras et al.

DNA methyltransferase expression in the mouse germ line during periods of de novo methylation

DNA methyltransferase (DNMT) 3A and DNMT3B are both active de novo DNA methyltransferases required for development, whereas DNMT3L, which has no demonstrable methyltransferase activity, is required for methylation of imprinted genes in the oocyte. We show here that different mechanisms are used to restrict access by these proteins to their targets during germ cell development. Transcriptional control of the Dnmt3l promoter guarantees that message is low or absent except during periods of de novo activity. Use of an alternative promoter at the Dnmt3a locus produces the shorter Dnmt3a2 transcript in the germ line and postimplantation embryo only, whereas alternative splicing of the Dnmt3b transcript ensures that Dnmt3b1 is absent in the male prospermatogonia. Control of subcellular protein localization is a common theme for DNMT3A and DNMT3B, as proteins were seen in the nucleus only when methylation was occurring. These mechanisms converge to ensure that the only time that functional products from each locus are present in the germ cell nuclei is around embryonic day 17.5 in males and after birth in the growing oocytes in females.

Chiton phylogeny (Mollusca Polyplacophora) and the placement of the enigmatic species Choriplax grayi (H. Adams & Angas)

Shallow marine chitons (Mollusca:Polyplacophora:Chitonida) are widespread and well described from established morphoanatomical characters, yet key aspects of polyplacophoran phylogeny have remained unresolved. Several species, including Hemiarthrum setulosum Carpenter in Dall, 1876, and especially the rare and enigmatic Choriplax grayi (Adams & Angas, 1864), defy systematic placement. Choriplax is known from only a handful of specimens and its morphology is a mosaic of key taxonomic features from two different clades. Here, new molecular evidence provides robust support for its correct association with a third different clade: Choriplax is placed in the superfamily Mopalioidea. Hemiarthrum is included in Cryptoplacoidea, as predicted from morphological evidence. Our multigene analysis of standard nuclear and mitochondrial markers demonstrates that the topology of the order Chitonida is divided into four clades, which have also been recovered in previous studies: Mopalioidea is sister to Cryptoplacoidea, forming a clade Acanthochitonina. The family Callochitonidae is sister to Acanthochitonina. Chitonoidea is resolved as the earliest diverging group within Chitonida. Consideration of this unexpected result for Choriplax and our well-supported phylogeny has revealed differing patterns of shell reduction separating the two superfamilies within Acanthochitonina. As in many molluscs, shell reduction as well as the de novo development of key shell features has occurred using different mechanisms, in multiple lineages of chitons.

A review of patents relating to therapeutic angiogenesis using endothelial progenitors and other vasculogenesis-related cell types

Stem and progenitor cells have generated considerable scientific and commercial interest in recent years due to their potential for novel cell therapy for a variety of medical conditions. A highly active research area in the field of regenerative medicine is vascular biology. Blood vessel repair and angiogenesis are key processes with endothelial progenitor cells (EPCs) playing a central role. Clinical trials for ischemic conditions, such as myocardial infarction and peripheral arterial disease, have suggested cell therapies to be feasible, safe, and potentially beneficial. Development of efficient methodologies to deliver EPC-based cytotherapies offers new hope for millions of patients with ischemic conditions. Evidence indicates that EPCs, depending on the subtype, mediate angiogenesis through different mechanisms. Differentiation into endothelium and complete integration into damaged vasculature was the first EPC mechanism to be proposed. However, many studies have demonstrated that vasoregulatory paracrine factor secretion by transplanted cells is also important. Many EPC subsets enhance angiogenesis and promote tissue repair by cytokine release without incorporating into the damaged vasculature. Whatever the mechanism, vascular repair and therapeutic angiogenesis using EPCs represent a realistic treatment option and also provides many commercialization opportunities. This review discusses recent advances in the EPC field whilst recounting relevant patents.

The Management of Long-Term Sickness Absence in Large Public Sector Healthcare Organisations: A Realist Evaluation Using Mixed Methods

Purpose The success of measures to reduce long-term sickness absence (LTSA) in public sector organisations is contingent on organisational context. This realist evaluation investigates how interventions interact with context to influence successful management of LTSA. Methods Multi-method case study in three Health and Social Care Trusts in Northern Ireland comprising realist literature review, semi-structured interviews (61 participants), Process-Mapping and feedback meetings (59 participants), observation of training, analysis of documents. Results Important activities included early intervention; workplace-based occupational rehabilitation; robust sickness absence policies with clear trigger points for action. Used appropriately, in a context of good interpersonal and interdepartmental communication and shared goals, these are able to increase the motivation of staff to return to work. Line managers are encouraged to take a proactive approach when senior managers provide support and accountability. Hindering factors: delayed intervention; inconsistent implementation of policy and procedure; lack of resources; organisational complexity; stakeholders misunderstanding each other’s goals and motives. Conclusions Different mechanisms have the potential to encourage common motivations for earlier return from LTSA, such as employees feeling that they have the support of their line manager to return to work and having the confidence to do so. Line managers’ proactively engage when they have confidence in the support of seniors and in their own ability to address LTSA. Fostering these motivations calls for a thoughtful, diagnostic process, taking into account the contextual factors (and whether they can be modified) and considering how a given intervention can be used to trigger the appropriate mechanisms.

Arsenite transport into paddy rice (Oryza sativa) roots

Here the mechanism of arsenite transport into paddy rice (Oryza sativa) roots, uptake of which is described by Michaelis-Menten kinetics, is reported. A recent study on yeast (Saccharomyces cerevisiae) showed that undissociated arsenite (its pK_a is 9.2) was transported across the plasma membrane via a glycerol transporting channel. To investigate whether the same mechanism of transport was involved for rice, competitive studies with glycerol, which is transported into cells via aquaporins, were performed. Glycerol competed with arsenite for transport in a dose-dependent manner, indicating that arsenite and glycerol uptake mechanisms were the same. Arsenate transport was unaffected by glycerol, confirming that arsenate and arsenite are taken up into cells by different mechanisms. Antimonite, an arsenite analogue that is transported into S. cerevisiae cells by aquaporins, also competed with arsenite transport in a dose-dependent manner, providing further evidence that arsenite is transported into rice roots via glycerol transporting channels. Mercury (Hg²⁺) inhibited both arsenite and arsenate uptake, suggesting that inhibition of influx was due to general cellular stress rather than the specific action of Hg²⁺ on aquaporins. Arsenite uptake by pea (Pisum sativum) and wheat (Triticum aestivum) was also described by Michaelis-Menten kinetics.

Reclamações em matéria de ambiente nos municípios envolventes à ria de Aveiro

O presente trabalho de investigação centra-se no estudo das reclamações em matéria de ambiente submetidas às Câmaras dos municípios envolventes à Ria de Aveiro entre os anos de 2000 e 2007. Pretendeu compreender-se de que forma podem ser caracterizadas as reclamações, nomeadamente a análise temporal, os principais atores envolvidos na apresentação e na resolução das reclamações, os imputados pelos problemas ambientais levantados, as tipologias de problemas de ambiente associadas às reclamações, o padrão territorial que assumem e as resoluções aplicadas. Procurou ainda compreender-se até que ponto a existência de um ecossistema em comum aos municípios, a Ria de Aveiro, influencia os tipos de problemas ambientais que têm sido alvo de reclamações e quais são os fatores que determinam as semelhanças e as diferenças encontradas no estudo das reclamações por municípios. A metodologia do trabalho consistiu, sumariamente, na revisão da literatura da especialidade com o objetivo de identificar o que tem sido desenvolvido nesse ramo de investigação, na caracterização da área de estudo e no desenvolvimento de uma estrutura metodológica para a identificação e a análise das reclamações e para a ponderação dos resultados com as perceções dos líderes locais através da realização de entrevistas. O enquadramento teórico do estudo salientou os principais aspetos referidos no domínio dos protestos ambientais e das reclamações do público sobre o ambiente, bem como o quadro concetual relativo à governação ambiental local. Adicionalmente, descreveram-se um breve panorama dos protestos ambientais em Portugal, dos quadros legislativos Europeu e nacional assentes no direito de acesso à informação ambiental e no princípio da participação, bem como os procedimentos locais para a apresentação de reclamações ambientais. Apresentou-se também a caracterização dos municípios abrangidos, destacando-se os principais aspetos socioeconómicos, ambientais, de infraestruturação, os instrumentos de planeamento e de gestão do território e do ambiente e o enquadramento institucional relativo à gestão ambiental nos municípios, constituindo informações relevantes para o enquadramento da área de estudo e um suporte útil para a análise e a interpretação dos resultados. Os resultados obtidos permitiram evidenciar que, no geral, há um aumento do número de reclamações ao longo dos anos. Como principais atores envolvidos, foi possível destacar os munícipes como os mais participativos, tendo se revelado também como os principais responsáveis pelos problemas ambientais observados. Para além das Câmaras Municipais, as instituições policiais surgem como as principais entidades requeridas na resolução dos problemas. As reclamações refletem sobretudo problemas localizados e que interferem com o quotidiano dos cidadãos, tais como a limpeza de terrenos, os depósitos de lixo a céu aberto ou o saneamento básico. Os problemas enunciados tendem a concentrar-se nas áreas mais urbanizadas e com maior densidade populacional. A intensidade, a tipologia e a distribuição territorial das reclamações são também determinadas pelas fronteiras administrativas. Contrariamente ao esperado, a Ria não constitui um fator mobilizador de reclamações ambientais dirigidas às Câmaras Municipais. Os diferentes mecanismos de submissão de reclamações, as políticas e prioridades de gestão ambiental local, a par da perceção ambiental das populações, influenciam esses resultados. A análise da resolução das reclamações mostrou que, embora a maior parte tenha sido equacionada pelos governos locais, uma percentagem significativa permaneceu em aberto. Apesar de ter sido detetada uma relevante concordância entre os principais problemas de ambiente referidos nos planos municipais de ambiente ou das Agendas 21 Locais existentes, as reclamações informam sobre problemas que nem sempre estão considerados naqueles instrumentos e que requerem atenção por parte dos governos locais. Adicionalmente, a ponderação entre os resultados obtidos a partir do estudo as reclamações e as perceções dos líderes locais acerca das exposições do público mostra que, apesar de uma perceção consistente sobre os problemas ambientais dominantes, há ainda um caminho relevante a percorrer para consolidar os sistemas municipais de receção, tratamento e análise das reclamações. O estudo desenvolvido ressalta o potencial que as reclamações ambientais incorporam enquanto fontes de informação sobre a tipologia de problemas ambientais persistentes, a sua localização e os principais atores envolvidos. Essa informação é crucial no momento em que se desenvolvem ou reveem instrumentos locais de gestão e de planeamento ambiental. Ao destacar o potencial das reclamações em matéria de ambiente, o trabalho propõe um conjunto de recomendações que permitem às Câmaras Municipais enriquecerem o sistema de gestão da informação proporcionada pelas reclamações, a sua utilização, e, em consequência, melhorar as relações de confiança entre o público e a Autarquia e a própria a governação ambiental local.

Reliable and energy efficient routing for ad hoc networks

In Mobile Ad hoc NETworks (MANETs), where cooperative behaviour is mandatory, there is a high probability for some nodes to become overloaded with packet forwarding operations in order to support neighbor data exchange. This altruistic behaviour leads to an unbalanced load in the network in terms of traffic and energy consumption. In such scenarios, mobile nodes can benefit from the use of energy efficient and traffic fitting routing protocol that better suits the limited battery capacity and throughput limitation of the network. This PhD work focuses on proposing energy efficient and load balanced routing protocols for ad hoc networks. Where most of the existing routing protocols simply consider the path length metric when choosing the best route between a source and a destination node, in our proposed mechanism, nodes are able to find several routes for each pair of source and destination nodes and select the best route according to energy and traffic parameters, effectively extending the lifespan of the network. Our results show that by applying this novel mechanism, current flat ad hoc routing protocols can achieve higher energy efficiency and load balancing. Also, due to the broadcast nature of the wireless channels in ad hoc networks, other technique such as Network Coding (NC) looks promising for energy efficiency. NC can reduce the number of transmissions, number of re-transmissions, and increase the data transfer rate that directly translates to energy efficiency. However, due to the need to access foreign nodes for coding and forwarding packets, NC needs a mitigation technique against unauthorized accesses and packet corruption. Therefore, we proposed different mechanisms for handling these security attacks by, in particular by serially concatenating codes to support reliability in ad hoc network. As a solution to this problem, we explored a new security framework that proposes an additional degree of protection against eavesdropping attackers based on using concatenated encoding. Therefore, malicious intermediate nodes will find it computationally intractable to decode the transitive packets. We also adopted another code that uses Luby Transform (LT) as a pre-coding code for NC. Primarily being designed for security applications, this code enables the sink nodes to recover corrupted packets even in the presence of byzantine attacks.

Effects of nanoparticles exposure in the mussel Mytilus Galloprovincialis

Tese de dout., Ciências do Mar, Terra e Ambiente (Ecotoxicologia), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2012

Study the function of the newly discovered TrkB receptor fragment (TrkB-ICD) formed by calpain cleavage

Tese de mestrado, Neurociências, Faculdade de Medicina, Universidade de Lisboa, 2016