983 resultados para key interactions


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The superfluid state of fermion-antifermion fields developed in our previous papers is generalized to include higher orbital and spin states. In addition to single-particle excitations, the system is capable of having real and virtual bound or quasibound composite excitations which are akin to bosons of spinJ P equal to0 �, 1�, 2+, etc. These pseudoscalar, vector, and tensor bosons can be massive or massless and provide the vehicles for strong, electromagnetic, weak, and gravitational interactions. The concept that the basic (unmanifest) fermion-antifermion interaction can lead to a multiplicity of manifest interactions seems to provide a basis for a unified field theory.

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The He+He+1 interactions have been studied, as a function of the internuclear separation R, in terms of the electronic forces acting on the nuclei and the change in the charge distribution. The analysis reveals that at large R the atomic densities are polarized inwards, causing an attractive force on each nucleus, while at small R the difference in the nature of the interactions in the 2Σu and 2Σg systems is noted. It is seen that the He+He+1 (2Σu) interaction is less attractive than the He+1+He+1 interaction at lower values of R.

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In a complex multitrophic plant-animal interaction system in which there are direct and indirect interactions between species, comprehending the dynamics of these multiple partners is very important for an understanding of how the system is structured. We investigated the plant Ficus racemosa L. (Moraceae) and its community of obligatory mutualistic and parasitic fig wasps (Hymenoptera: Chalcidoidea) that develop within the fig inflorescence or syconium, as well as their interaction with opportunistic ants. We focused on temporal resource partitioning among members of the fig wasp community over the development cycle of the fig syconia during which wasp oviposition and development occur and we studied the activity rhythm of the ants associated with this community. We found that the seven members of the wasp community partitioned their oviposition across fig syconium development phenology and showed interspecific variation in activity across the day-night cycle. The wasps presented a distinct sequence in their arrival at fig syconia for oviposition, with the parasitoid wasps following the galling wasps. Although fig wasps are known to be largely diurnal, we documented night oviposition in several fig wasp species for the first time. Ant activity on the fig syconia was correlated with wasp activity and was dependent on whether the ants were predatory or trophobiont-tending species; only numbers of predatory ants increased during peak arrivals of the wasps.

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A theoretical conformational analysis of fenamates, which are N-arylated derivatives of anthranilic acid or 2-aminonicotinic acid with different substituents on the aryl (phenyl) group, is reported. The analysis of these analgesics, which are believed to act through the inhibition of prostaglandin biosynthesis, was carried out using semi-empirical potential functions. The results and available crystallographic observations have been critically examined in terms of their relevance to drug action. Crystallographic studies of these drugs and their complexes have revealed that the fenamate molecules share a striking invariant feature, namely, the sixmembered ring bearing the carboxyl group is coplanar with the carboxyl group and the bridging imino group,the coplanarity being stabilized by resonance interactions and an internal hydrogen bond between the imino and carboxyl groups. The results of the theoretical analysis provide a conformational rationale for the observed invariant coplanarity. The second sixmembered ring, which provides hydrophobicity in a substantial part of the molecule, has limited conformational flexibility in meclofenamic, mefenamic and flufenamic acids. Comparison of the conformational energy maps of these acids shows that they could all assume the same conformation when bound to the relevant enzyme. The present study provides a structural explanation for the difference in the activity of niflumic acid, which can assume a conformation in which the whole molecule is nearly planar. The main role of the carboxyl group appears to be to provide a site for intermolecular interactions in addition to helping in stabilizing the invariant coplanar feature and providing hydrophilicity at one end of the molecule. The fenamates thus provide a good example of conformation- dependent molecular asymmetry.

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C~HaO 4, Mr=204.2, monoclinic, P2Jn,a=3.900(1), =37.530(6), c=6.460(1)A, fl=103.7 (1) °, V= 918.5 (5) A 3, Z = 4, D m = 1.443, D x --- 1.476 Mg m -3, Cu Ks, 2 = 1.5418 ,/k, /t = 0.86 mm -~, F(000) = 424, T= 293 K, R = 0.075 for 1019 significant reflections. Molecules pack in fl-type stacking mode which is characterized by the close packing of parallel and nearly planar reactive double bonds with a separation of 3.900/~ along the a axis.The syn head-head dimer obtained is the direct consequence of this packing arrangement. Molecular packing is stabilized by intermolecular C-H...O hydrogen bonding. Analysis of acetoxy...acetoxy interactions in the acetoxy compounds retrieved from the Cambridge Structural Database reveal that the majority of them are anti-dipolar.

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This paper presents the detailed dynamic digital simulation for the study of phenomenon of torsional interaction between HVDC-Turbine generator shaft, dynamics using the novel converter model presented in [ 1 ] The system model includes detailed representation of the synchronous generator and the shaft dynamics, the ac and dc network transients. The results of a case study indicate the various factors that influence the torsional interaction.

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The interaction energies between (Ala)10 and alpha-helix fragment and different nucleotide sequences in right-handed B-form have been optimized using semi-empirical potential energy functions. The energies are calculated for two different orientations of the alpha-helix, viz., when the alpha-helix axis taken in the N----C direction is (i) parallel and (ii) antiparallel to the 5'-3' ascending strand of DNA, proximal to it. When both the DNA molecule as well as the alpha-helix are treated as rigid molecules it is found that a polyalanine alpha-helix has slightly more favourable contacts when it is in the proximity of a four nucleotide sequence of 5'-(N-A-T-N)-3' type, where N is either a purine or a pyrimidine. However, when the two interacting molecules are allowed to undergo local structural variations then the interaction energy appears to be independent of the base sequence confirming the non-specific nature of these interactions.

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The in situ cryo-crystallization study of benzyl derivatives reveals that the molecular packing in these compounds is either through methylene (sp(3)) C-H center dot center dot center dot pi or aromatic (sp(2)) C-H center dot center dot center dot pi interactions depending on the level of acidity of the benzyl proton. These studies of low melting compounds bring out the subtle features of such weak interactions and point to the directional preferences depending on the nature (electron withdrawing, polarizability) of the neighbouring functional group.

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Background: Dengue virus along with the other members of the flaviviridae family has reemerged as deadly human pathogens. Understanding the mechanistic details of these infections can be highly rewarding in developing effective antivirals. During maturation of the virus inside the host cell, the coat proteins E and M undergo conformational changes, altering the morphology of the viral coat. However, due to low resolution nature of the available 3-D structures of viral assemblies, the atomic details of these changes are still elusive. Results: In the present analysis, starting from C alpha positions of low resolution cryo electron microscopic structures the residue level details of protein-protein interaction interfaces of dengue virus coat proteins have been predicted. By comparing the preexisting structures of virus in different phases of life cycle, the changes taking place in these predicted protein-protein interaction interfaces were followed as a function of maturation process of the virus. Besides changing the current notion about the presence of only homodimers in the mature viral coat, the present analysis indicated presence of a proline-rich motif at the protein-protein interaction interface of the coat protein. Investigating the conservation status of these seemingly functionally crucial residues across other members of flaviviridae family enabled dissecting common mechanisms used for infections by these viruses. Conclusions: Thus, using computational approach the present analysis has provided better insights into the preexisting low resolution structures of virus assemblies, the findings of which can be made use of in designing effective antivirals against these deadly human pathogens.

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Sosiaali- ja terveysministeriön 2006 julkaiseman vanhustyön ja geriatrisen lääkehoidon kehittämistä koskevan selvityksen yhtenä tärkeänä huolenaiheena oli iäkkäiden lääkehoidon useat epäkohdat, kuten iäkkäitä hoitavien hoitajien lääkeosaamiseen liittyvät puutteet ja ongelmat. Yksi keino parantaa iäkkäitä hoitavien eri tahojen lääkehoito-osaamista on täydennyskoulutus, johon kaikilla sosiaali- ja terveydenhuollon ammattiryhmillä on oikeus ja velvollisuus. Täydennyskoulutuksella pystytään myös kehittämään organisaatioiden toimintaa ja tuottamaan uusia, parempia palveluita. Tutkimuksessa selvitettiin Lohjan, Siuntion, Inkoon ja Karjalohjan muodostaman sosiaali- ja terveydenhuollon yhteistoiminta-alueen LOSTin kotihoidon yksiköiden iäkkäiden lääkehoitoihin liittyviä koulutustarpeita. Tämän tutkimuksen avulla syvennettiin samalle tutkimusryhmälle tehdyn kyselytutkimuksen tuloksia. Tutkimusaineistona käytettiin LOST-alueen kotihoidon yksiköiden hoitajille (n=150) farmaseutin lopputyönä tehtyä kyselyaineistoa sekä työntekijöille (n=6) ja esimiehille (n=6) tehtyjä erillisiä ryhmäkeskusteluja. Lisäksi näkökulman laajentamiseksi ja moniammatillisuuden korostamiseksi aineistona käytettiin kotihoidon asiakkaita hoitavien lääkärien (n=4) teemahaastatteluja. Kyselyaineistosta analysoitiin erikseen sairaanhoitajien, lähihoitajien ja kodinhoitajien koulutustarpeet. Samat asiat nousivat esille kunkin ammattiryhmän tuloksissa. Tärkeimpinä lääkehoito-osaamiseen liittyvinä teoreettisina koulutettavina asioina kyselystä nousivat esille iäkkäiden farmakokinetiikka ja lääkkeiden käyttöön liittyvät erityispiirteet, lääkkeiden vaikutukset, lääkkeiden haittavaikutukset sekä lääkkeiden yhteisvaikutukset ja yhteensopivuus. Lisäksi teoreettisista taidoista nousi hoitotyön etiikkaan liittyvät tarkkuus ja huolellisuus työssä. Käytännön taidoista tärkeimpinä koulutettavina aiheina kyselystä nousivat asiakkaiden lääkehoidon ja voinnin seuranta, lääkkeiden jakaminen sekä lääkkeiden annosteluun liittyen se, että annostellaan oikeaa lääkettä ja vahvuutta, oikea annos ja oikeaan aikaan sekä oikeat antotavat. Ryhmäkeskusteluista ja lääkärien teemahaastatteluista haettiin syvempää ymmärrystä kyselyn tuloksiin. Yksi tärkeimmistä tämän laadullisen tutkimuksen löydöksistä oli kotihoidon yhteistyöhön liittyvät epäkohdat. Lääkehoitojen toteuttamista ja seurantaa voitaisiin tulosten perusteella parantaa lääkärien ja kotihoidon hoitajien yhteisellä koulutuksella. Tärkeimpiä sairauksia tai oireita, joihin hoitajat toivoisivat yhteisiä toimintakäytäntöjä, ovat diabetes, sydän- ja verisuonisairaudet, kipu, muistisairaudet sekä psyykensairaudet. Lisäksi koulutusaiheiksi tutkimuksesta nousivat iäkkäiden lääkehoidon erityispiirteet, lääkkeiden antoreitit ja lääkemuodot. Kyselyn sekä ryhmäkeskustelujen ja lääkärien teemahaastattelujen tuloksista tehtiin lopuksi synteesi, jonka lopputuloksena LOST-alueen kotihoidon hoitohenkilöstölle sekä kotihoidon lääkäreille koottiin yhteinen tarvelähtöinen täydennyskoulutussuunnitelma. Suunnitelma tehtiin aineistosta nousseiden koulutusaiheiden pohjalta, eikä siihen lisätty aiheita tutkimuksen ulkopuolelta.

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Humic lakes are abundant in the temperate and cold regions of the Boreal Zone. High levels of water colour and strong thermal stratification of humic lakes limit the potential fish habitats and give a special role to the intraspecific and interspecific interactions. Water colour has different effects on species depending on species-specific life-history traits and trophic interactions. Fish species whose success in predation is based on visual cues are more susceptible to suffer in competition. The main aim of the thesis was to demonstrate the effects of water colour on European perch (Perca fluviatilis) in humic lakes. The contribution of water colour to diet, feeding, growth and competitive interactions of fish was studied both in laboratory and in small humic lakes with varying levels of water colour. The main findings of the thesis were that water colour has different effects on species, depending on species-specific life-history traits and trophic interactions. Water colour affected visually-oriented perch feeding and growth negatively, and the prolonged benthic feeding phase of perch resulting from the increased water colour could increase intraspecific competition in perch populations and may result in a partial bottleneck in growth for perch. Moreover, water colour may act as a proximate factor behind the population dependency of sexual growth dimorphism in perch.

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Six crystal structures of substituted 2-chloroquinoline derivatives have been analysed to evaluate the role of Cl atom as a self recognizing unit resulting in the formation of Cl center dot center dot center dot Cl and C-H center dot center dot center dot Cl interactions to generate supramolecular assembly in the solid state. The features of Type I and Type II geometries associated with Cl center dot center dot center dot Cl interactions have been analysed to show directional preferences leading to differences in the packing motifs in these crystal structures. C-H center dot center dot center dot Cl interactions are generated exclusively in structures depicting Type II Cl center dot center dot center dot Cl interaction have been observed in these structures.

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Use of adverse drug combinations, abuse of medicinal drugs and substance abuse are considerable social problems that are difficult to study. Prescription database studies might fail to incorporate factors like use of over-the-counter drugs and patient compliance, and spontaneous reporting databases suffer from underreporting. Substance abuse and smoking studies might be impeded by poor participation activity and reliability. The Forensic Toxicology Unit at the University of Helsinki is the only laboratory in Finland that performs forensic toxicology related to cause-of-death investigations comprising the analysis of over 6000 medico-legal cases yearly. The analysis repertoire covers most commonly used drugs and drugs of abuse, and the ensuing database contains also background information and information extracted from the final death certificate. In this thesis, the data stored in this comprehensive post-mortem toxicology database was combined with additional metabolite and genotype analyses that were performed to complete the profile of selected cases. The incidence of drug combinations possessing serious adverse drug interactions was generally low (0.71%), but it was notable for the two individually studied drugs, a common anticoagulant warfarin (33%) and a new generation antidepressant venlafaxine (46%). Serotonin toxicity and adverse cardiovascular effects were the most prominent possible adverse outcomes. However, the specific role of the suspected adverse drug combinations was rarely recognized in the death certificates. The frequency of bleeds was observed to be elevated when paracetamol and warfarin were used concomitantly. Pharmacogenetic factors did not play a major role in fatalities related to venlafaxine, but the presence of interacting drugs was more common in cases showing high venlafaxine concentrations. Nicotine findings in deceased young adults were roughly three times more prevalent than the smoking frequency estimation of living population. Contrary to previous studies, no difference in the proportion of suicides was observed between nicotine users and non-nicotine users. However, findings of abused substances, including abused prescription drugs, were more common in the nicotine users group than in the non-nicotine users group. The results of the thesis are important for forensic and clinical medicine, as well as for public health. The possibility of drug interactions and pharmacogenetic issues should be taken into account in cause-of-death investigations, especially in unclear cases, medical malpractice suspicions and cases where toxicological findings are scarce. Post-mortem toxicological epidemiology is a new field of research that can help to reveal problems in drug use and prescription practises.

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The structures of [Nd-2(Acc(6))(H2O)(6)](ClO4)(6) .(H2O)(6) (1) [Er-2(Acc(6))(4)(H2O)(8)](ClO4)(6) .(H2O)(11) (2) and [Ca-5(Acc(6))(12)(H2O)(6)](ClO4)(10).(H2O)(4) (3) (Acc(6) = 1-aminocyclohexane-1-carboxylic acid) have been determined by X-ray crystallography. The lanthanide complexes 1 and 2 are dimeric in which two lanthanide cations are bridged by four carboxylato groups of Acc(6) molecules. In addition, the neodymium complex (1) features the unidentate coordination of the carboxyl group of an Acc(6) molecule in place of a water molecule in the erbium complex (2). The coordination number in both 1 and 2 is eight. The calcium Acc(6) complex (3) is polymeric; three different calcium environments are observed in the asymmetric unit. Two calcium ions are hexa-coordinated and one is hepta-coordinated. Considerable differences are observed between the solid state structures of Ln(III) and Ca-II complexes of Acc(6