Search results for " effect"

Interspecific extrinsic and intrinsic competitive interactions in egg parasitoids

2012

Interspecific competitive interactions can occur either between adult parasitoids searching/exploiting hosts (extrinsic competition) or between parasitoid larvae developing within the same host (intrinsic competition). Understanding how interspecific competition between parasitoids can affect pest suppression is important for improving biological pest control. The purpose of this work was to review both extrinsic and intrinsic competition between egg parasitoid species. These are organisms that are often candidates for biological control programs due to their ability to kill the pest before the crop feeding stage. We first reviewed the literature about interspecific competitive abilities of…

On Transition Structures for Hydride Transfer Step: A Theoretical Study of the Reaction Catalyzed by Dihydrofolate Reductase Enzyme

1996

Abstract A theoretical study is presented of the catalytic mechanism of dihydrofolate reductase (DHFR) enzyme based upon the characterization of the transition structure (TS) for the hydride transfer step. Analytical gradients at AM1 and PM3 semiempirical levels have been used to characterize the saddle point of index one (SPi-1) on global energy hypersurface for the hydride transfer in the active site of DHFR enzyme. The geometry, stereochemistry, electronic structure, and transition vector (TV) components associated to SPi-1 are qualitatively computational level independent. The TV amplitudes show primary and secondary isotope effects to be strongly coupled. The geometrical arrangement of…

Bacteria and Complement — A Historical Review

1985

In the second half of the nineteenth century, shortly after it became clear from the work of Louis Pasteur (1822–1895) and Robert Koch (1843–1910) that microorganisms cause infectious diseases, extensive studies were untertaken to elucidate the mechanisms of protection from and resistance to infections. This early history of the investigation of immunity is characterized by the dispute between two opposing schools, the protagonists of the “cellular” and the “humoral” theories. Eli Metchnikoff (1845–1919) was the first to recognize the general significance of the phenomenon of phagocytosis in animal tissues. In 1883, he published his first papers in the presentation of the theory of phagocyt…

Hydrophobically Directed Aldol Reactions: Polystyrene-SupportedL-Proline as a Recyclable Catalyst for Direct Asymmetric Aldol Reactions in the Presen…

2007

The cover picture shows the aldol reaction between ketones and arylaldehydes carried out by using a polystyrene-supported L-proline catalyst. This material furnishes aldol products in high yields and stereoselectivities. Screening of solvents showed that these reactions take place only in the presence of water. This solvent effect, coupled with the high stereoselectivities observed, has been explained by the formation of a hydrophobic core in the inner surface of the resin with the hydrophilic proline moiety in the resin/water interface. Such a microenvironment promotes the aldol reaction and increases the stereoselectivity. Recycling investigations have shown that this material can be reus…

Study of Pinna nobilis growth from inner record: How biased are posterior adductor muscle scars estimates?

2011

abstract Article history:Received 14 June 2011Received in revised form 19 July 2011Accepted 20 July 2011Available online 17 August 2011Keywords:BivalviaEndangered speciesMediterraneanSclerochronologySpain Previous studies have shown that the external growth records of the posterior adductor muscle scar (PAMS)ofthe bivalve Pinna nobilisareincomplete and donot produce accurate ageestimations. We havedeveloped anew methodology to study age and growth using the inner record of the PAMS, which avoids the necessity ofcostly in situ shell measurements or isotopic studies. Using the inner record we identified the positions ofPAMS previously obscured by nacre and estimated the number of missing recor…

Online Hate Does Not Stay Online – How Implicit and Explicit Attitudes Mediate the Effect of Civil Negativity and Hate in User Comments on Prosocial …

2020

Abstract Incivility and hateful language in user comments are met with growing concern among politicians, the general public, and scholars. There are fears that such comments may decrease social cohesion and ultimately result in less prosocial behavior among citizens. We investigate whether hate, or even civil negativity in user comments alone, inhibit actual prosocial behavior through recipients’ explicit and implicit attitudes. In an online experiment, 253 participants read user comments (neutral, civil-negative, hateful) about refugees and received five Euros which they could donate for a refugee aid organization or keep for themselves. The results show that participants confronted with …

Use of molecular topology in the selection of new cytostatic drugs

2000

Abstract Connectivity indices are the topological descriptors that are able to predict different chemical and biological properties of the organic compounds. Recently, our research group has demonstrated their usefulness in selecting new cytostatic compounds, all of them showing antibacterial activity. In this paper we realize that this ability is considerably increased by using our home-made pharmacological distribution diagrams (PDDs) together with the topological charge indices, so that the efficient selection of new candidates within heterogeneous sets of compounds is possible. This is a straightforward way for the design and/or selection of new active compounds on virtually any type of…

2015

Chemical ligation has been used to alter motions in specific regions of dihydrofolate reductase from E. coli and to investigate the effects of localized motional changes on enzyme catalysis. Two isotopic hybrids were prepared; one with the mobile N-terminal segment containing heavy isotopes (2H, 13C, 15N) and the remainder of the protein with natural isotopic abundance, and the other one with only the C-terminal segment isotopically labeled. Kinetic investigations indicated that isotopic substitution of the N-terminal segment affected only a physical step of catalysis, whereas the enzyme chemistry was affected by protein motions from the C-terminal segment. QM/MM studies support the idea th…

Neutralizing human antibodies against CD55 and CD59 targeted to lymphoma cells in vivo potentiate the therapeutic effect of Rituximab

2007

Linking Economic Stress to Marital Quality Among Finnish Marital Couples

1998

Structural equation modeling was used to test the mediators of economic circumstances on marital quality using a sample of married or cohabiting 36-year-old Finnish men ( n = 133) and women ( n = 117). The model tested was an adapted version of the model presented by Conger, Ge, and Lorenz. For the men, the results were consistent with the proposed model: Poor employment status caused economic strain and affected the lives of the men to the extent that current economic strain increased expected financial strain, leading to greater depression and greater hostility in the marriage, both of which, in turn, predicted poor marital quality. For the women, poor economic circumstances and, in part…