Showing papers by "University of Amsterdam published in 2000"
TL;DR: The working conditions of content-based retrieval: patterns of use, types of pictures, the role of semantics, and the sensory gap are discussed, as well as aspects of system engineering: databases, system architecture, and evaluation.
Abstract: Presents a review of 200 references in content-based image retrieval. The paper starts with discussing the working conditions of content-based retrieval: patterns of use, types of pictures, the role of semantics, and the sensory gap. Subsequent sections discuss computational steps for image retrieval systems. Step one of the review is image processing for retrieval sorted by color, texture, and local geometry. Features for retrieval are discussed next, sorted by: accumulative and global features, salient points, object and shape features, signs, and structural combinations thereof. Similarity of pictures and objects in pictures is reviewed for each of the feature types, in close connection to the types and means of feedback the user of the systems is capable of giving by interaction. We briefly discuss aspects of system engineering: databases, system architecture, and evaluation. In the concluding section, we present our view on: the driving force of the field, the heritage from computer vision, the influence on computer vision, the role of similarity and of interaction, the need for databases, the problem of evaluation, and the role of the semantic gap.
6,447 citations
TL;DR: In this paper, the authors briefly review the contemporary literature on relationship banking and discuss how relationship banking fits into the core economic services provided by banks and point at its costs and benefits.
2,302 citations
TL;DR: An analysis of response latencies shows that when an image is presented to the visual system, neuronal activity is rapidly routed to a large number of visual areas, but the activity of cortical neurons is not determined by this feedforward sweep alone.
2,148 citations
TL;DR: The authors investigated the prevalence of five news frames identified in earlier studies on framing and framing effects: attribution of responsibility, conflict, human interest, economic consequences, and morality, and found that the use of news frames depended on both the type of outlet and the topic most significant differences were not between media (television vs the press) but between sensationalist vs serious types of news outlets.
Abstract: We investigated the prevalence of 5 news frames identified in earlier studies on framing and framing effects: attribution of responsibility, conflict, human interest, economic consequences, and morality We content analyzed 2,601 newspaper stories and 1,522 television news stories in the period surrounding the Amsterdam meetings of European heads of state in 1997 Our results showed that, overall, the attribution of responsibility frame was most commonly used in the news, followed by the conflict, economic consequences, human interest, and morality frames, respectively The use of news frames depended on both the type of outlet and the type of topic Most significant differences were not between media (television vs the press) but between sensationalist vs serious types of news outlets Sober and serious newspapers and television news programs more often used the responsibility and conflict frames in the presentation of news, whereas sensationalist outlets more often used the human interest frame
2,006 citations
TL;DR: This article showed that as interbank competition increases, banks make more relationship loans, but each has lower added value for borrowers, while capital market competition reduces relationship lending and bank lending shrinks.
Abstract: How will banks evolve as competition increases from other banks and from the capital market? Will banks become more like capital market underwriters and offer passive transaction loans or return to their roots as relationship lending experts? These are the questions we address. Our key result is that as interbank competition increases, banks make more relationship loans, but each has lower added value for borrowers. Capital market competition reduces relationship lending ~and bank lending shrinks!, but each relationship loan has greater added value for borrowers. In both cases, welfare increases for some borrowers but not necessarily for all. RAPID CHANGES IN F INANCIAL SERVICES ARE threatening commercial banks. In the United States, mutual funds such as Fidelity and Merrill Lynch compete for banks’ core deposits. Investment banks, armed with a variety of financial market innovations, challenge banks’ traditional lending products. Banks also find themselves in greater competition with one another as globalization and deregulation weaken geographic boundaries and encourage crossborder ~Europe! and interstate ~U.S.! banking. These developments raise numerous fundamental questions. Will the relationship-oriented European bank system survive competitive pressures in this changing environment? Will U.S. banks focus more on “relationship banking” 1 —whereby banks invest in building relationships with borrowers—or on “transaction banking,” which involves “arm’s length” transactions rather
1,458 citations
TL;DR: The results demonstrate that distinct classes of PI3K control the macroautophagic pathway in opposite directions.
1,194 citations
TL;DR: For pharmaceutical development purposes, it seems logical to restrict the development of new innovative compounds to a MW of under 500 Dalton, when topical dermatological therapy or percutaneous systemic therapy or vaccination is the objective.
Abstract: Human skin has unique properties of which functioning as a physicochemical barrier is one of the most apparent. The human integument is able to resist the penetration of many molecules. However, especially smaller molecules can surpass transcutaneously. They are able to go by the corneal layer, which is thought to form the main deterrent. We argue that the molecular weight (MW) of a compound must be under 500 Dalton to allow skin absorption. Larger molecules cannot pass the corneal layer. Arguments for this "500 Dalton rule" are; 1) virtually all common contact allergens are under 500 Dalton, larger molecules are not known as contact sensitizers. They cannot penetrate and thus cannot act as allergens in man; 2) the most commonly used pharmacological agents applied in topical dermatotherapy are all under 500 Dalton; 3) all known topical drugs used in transdermal drug-delivery systems are under 500 Dalton. In addition, clinical experience with topical agents such as cyclosporine, tacrolimus and ascomycins gives further arguments for the reality of the 500 Dalton rule. For pharmaceutical development purposes, it seems logical to restrict the development of new innovative compounds to a MW of under 500 Dalton, when topical dermatological therapy or percutaneous systemic therapy or vaccination is the objective.
1,132 citations
TL;DR: In this paper, regularities in the incidence of over-and undereducation are outlined, as well as consequences for individual earnings, using empirical studies from five countries spanning an interval of two decades, and the results are confronted with three theoretical models (search, human capital and assignment), but none of these is convincingly related to the specification of the earnings function.
953 citations
TL;DR: In this article, a direct correspondence between the classical evolution equations of supergravity and the renormalization group (RG) equations of the dual $4-d$ large $N$ gauge theory was proposed.
Abstract: We propose a direct correspondence between the classical evolution equations of $5-d$ supergravity and the renormalization group (RG) equations of the dual $4-d$ large $N$ gauge theory. Using standard Hamilton-Jacobi theory, we derive first order flow equations for the classical supergravity action $S$, that take the usual form of the Callan-Symanzik equations, including the corrections due to the conformal anomaly. This result gives direct support for the identification of $S$ with the quantum effective action of the gauge theory. In addition we find interesting new relations between the beta-functions and the counterterms that affect the $4-d$ cosmological and Newton constant.
910 citations
TL;DR: In this paper, the importance of work-group identification relative to organizational identification (OID) was investigated and the work group identification was predicted to be stronger than OID as well as more predictive of organizational attitudes and behaviour.
Abstract: Adopting the social identity perspective on organizational identification proposed by Ashforth and Mael (1989), the present study tested two hypotheses concerning the importance of work-group identification (WID) relative to organizational identification (OID). WID was predicted to be stronger than OID as well as more predictive of organizational attitudes and behaviour. Data about employees’ WID, OID, job satisfaction, turnover intentions, job involvement, and job motivation from two samples (N = 76 and N = 163) supported these predictions. We conclude that our understanding of organizational attitudes and behaviour has much to gain by an open eye for the multiple foci of identification that are associated with organizational membership, and that managerial practice may benefit from an increased focus on the work group.
897 citations
TL;DR: In this paper, the authors argue that institutional factors have a greater impact on wind energy facility siting, and discuss two examples of how institutional factors shape the level of support when implementing wind power.
TL;DR: The history of “ligand effects” in catalysis, a range of reactions for which a notable effect has been observed, and some of the established examples of bite angle effects involve diphosphine ligands.
Abstract: phinoethane) seemed mainly to stabilize intermediates, and often the catalytic reactions were slower when dppe was used instead of the most common monodentate triphenylphosphine. We will briefly review the history of “ligand effects” in catalysis before discussing a range of reactions for which a notable effect has been observed. It has taken quite some time before the positive effect that bidentates can have on selectivities and rates of catalytic reactions was fully recognized. Most of the established examples of bite angle effects involve diphosphine ligands. Therefore, many important catalysts containing a chelate ligand such as bipyridine and diimine will fall outside the scope of this review. The connecting bridge in these bidentates does play a dominant role in the performance of these catalysts, but systematic studies have not been published. The effects of phosphine ligands in catalysis have been known for quite some time. One of the first reports involves the use of triphenylphosphine in the “Reppe” chemistry, the reactions of alkynes, alcohols, and carbon monoxide.1 It was found that formation of acrylic esters was much more efficient using NiBr2(PPh3)2 than NiBr2 without ligand. In the commercial system, though, a phosphine-free catalyst is used. While the reaction was not yet understood mechanistically, the use of phosphines in catalysis attracted the attention of the petrochemical industry worldwide. An early example of a phosphine ligand modified catalytic process is the Shell process for alkene hydroformylation using a cobalt catalyst containing a trialkylphoshine.2 The reaction requires higher temperatures, but it leads to more linear product as compared to the unmodified catalyst. The general mechanism of the hydroformylation reaction has been known for a long time.3 Hydrocyanation as used by Du Pont is another early example of an industrially applied catalytic reaction employing ligands.4 It is a nickel-catalyzed reaction in which aryl phosphite ligands are used for the production of adiponitrile. The development of this process has played a key role in the introduction of the now very common study of “ligand effects” in the field of homogeneous catalysis by organometallic complexes.5 While several industries were working on new homogeneous catalysts, important contributions to the new field were made in academia in the early 1960s with the appearance of the first phosphinemodified hydrogenation catalysts. An early example of a phosphine-free ruthenium catalyst was published by Halpern.6 Triphenylphosphine-modified platinumtin catalysts for the hydrogenation of alkenes were reported by Cramer from Du Pont in 1963.7 In the same year Breslow (Hercules) included a few phosFigure 1. Bite angle: The ligand-metal-ligand angle of bidentate ligands. 2741 Chem. Rev. 2000, 100, 2741−2769
TL;DR: Work motivation and performance were analyzed from the perspective of social identity theory and self-categorisation theory as mentioned in this paper, and the relation of organisational identification with the motivation to exert effort on behalf of the collective.
Abstract: Work motivation and performance were analysed from the perspective of social identity theory and self-categorisation theory. Central in this analysis is the relation of organisational identification with the motivation to exert effort on behalf of the collective. A theoretical analysis as well as a review of empirical studies of the relationship of organisational identification with motivation and performance leads to the conclusion that identification is positively related to work motivation, task performance, and contextual performance to the extent that (a) social identity is salient, and (b) high performance is perceived to be in the group’s or organisation’s interest.
TL;DR: In this article, the authors give rigorous definitions of the rebound effect not only in the well described single commodity case, but also for a multiple commodity case and show that the familiar laws for the single case do not hold for the multiple case.
TL;DR: The authors compare a partners condition where the same small group of subjects play a repeated publi c good game to a strangers condition where subjects play this game in changing group formations and interpret subjects' behavior in terms of conditional cooperation which is characterized by both futureoriented and reactive behavior.
Abstract: We compare a partners condition where the same small group of subjects plays a repeated publi c good game to a strangers condition where subjects play this game in changing group formations. Subjects in the partners conditi on contribute from t he first period on significantly more to the publi c good than subjects in the strangers conditi on. In the strangers conditi on, contributions show a continual decay, whil e in the partners conditi on, contributions fluctuate on a high level until t hey decrease in the final periods. We interpret subjects’ behavior in terms of conditional cooperation which is characterized by both future-oriented and reactive behavior.
TL;DR: In this article, the integration of intellectual ability, learning style, personality and achievement motivation as predictors of academic success in higher education in the Netherlands was investigated. But no positive association with academic success was detected for the meaning directed, reproduction directed and application directed learning style.
TL;DR: Reducing the rate of substrate formation by OGT 918 improves key clinical features of non-neuronopathic Gaucher's disease and justifies further trials in this and other glycosphingolipid storage disorders.
TL;DR: Although adequately dosed vitamin K antagonists are effective in patients with malignant disease, the incidence of thrombotic and bleeding complications remains higher than in patients without malignancy.
Abstract: PURPOSE: Initial heparinization followed by vitamin K antagonists is the treatment of choice for patients with venous thromboembolism. There is controversy whether known malignancy is a risk factor for recurrences and bleeding complications during this treatment. Furthermore, the incidence of such events in these patients is dependent on the achieved International Normalized Ratio (INR). The aim of this study was to assess the incidence of venous thromboembolic recurrence and major bleeding among patients with venous thromboembolism in relation to both malignancy and the achieved INR. PATIENTS AND METHODS: In a retrospective analysis, the INR-specific incidence of venous thromboembolic and major bleeding events during oral anticoagulant therapy was calculated separately for patients with and without malignancy. Eligible patients participated in two multicenter, randomized clinical trials on the initial treatment of venous thromboembolism. Patients were initially treated with heparin (standard or low-molec...
TL;DR: The design and operation issues for reactive distillation systems are considerably more complex than those involved for either conventional reactors or conventional distillation columns as discussed by the authors, and the introduction of an in situ separation function within the reaction zone leads to complex interactions between vapor-liquid equilibrium, vapor−liquid mass transfer, intra-catalyst diffusion, and chemical kinetics.
TL;DR: The in vivo behavior of yeast glycolysis can be understood in terms of the in vitro kinetic properties of the constituent enzymes in nongrowing, anaerobic, compressed Saccharomyces cerevisiae.
Abstract: This paper examines whether the in vivo behavior of yeast glycolysis can be understood in terms of the in vitro kinetic properties of the constituent enzymes. In nongrowing, anaerobic, compressed Saccharomyces cerevisiae the values of the kinetic parameters of most glycolytic enzymes were determined. For the other enzymes appropriate literature values were collected. By inserting these values into a kinetic model for glycolysis, fluxes and metabolites were calculated. Under the same conditions fluxes and metabolite levels were measured. In our first model, branch reactions were ignored. This model failed to reach the stable steady state that was observed in the experimental flux measurements. Introduction of branches towards trehalose, glycogen, glycerol and succinate did allow such a steady state. The predictions of this branched model were compared with the empirical behavior. Half of the enzymes matched their predicted flux in vivo within a factor of 2. For the other enzymes it was calculated what deviation between in vivo and in vitro kinetic characteristics could explain the discrepancy between in vitro rate and in vivo flux.
TL;DR: Results showed that negotiators were less contentious, engaged in more problem solving, and achieved higher joint outcomes when they had a prosocial rather than egoistic motive, but only when resistance to yielding was high (or unknown) rather than low.
Abstract: A meta-analysis of 28 studies examined support for the Theory of Cooperation and Competition (M. Deutsch, 1973) and Dual Concern Theory (D. G. Pruitt & J. Z. Rubin, 1986). Effects of social motive (prosocial vs. egoistic) and resistance to yielding (high vs. low vs. unknown) on contenting, problem solving, and joint outcomes were examined. Consistent with Dual Concern Theory, results showed that negotiators were less contentious, engaged in more problem solving, and achieved higher joint outcomes when they had a prosocial rather than egoistic motive, but only when resistance to yielding was high (or unknown) rather than low. The authors also explored the moderating effects of study characteristics and found effects for participation inducement (class exercise, participant pool), for publication status, and for treatment of no-agreement dyads.
TL;DR: A central role for microphytobenthos in moderating carbon flow in coastal sediments is indicated, and C-13 assimilation increased until day 3, and carbon isotope analysis of polar lipid derived fatty acids specific for bacteria showed rapid, significant transfer from benthic algae to bacteria.
Abstract: At two intertidal sites (one sandy and one silty, in the Scheldt estuary, The Netherlands), the fate of microphytobenthos was studied through an in situ C-13 pulse- chase experiment. Label was added at the beginning of low tide, and uptake of C-13 by algae was linear during the whole period of tidal exposure (about 27 mg m(-2) h(-1) in the top millimeter at both sites). The C-13 fixed by microphytobenthos was rapidly displaced toward deeper sediment layers (down to 6 cm), in particular at the dynamic, sandy site. The residence times of microphytobenthos with respect to external losses (resuspension and respiration) were about 2.4 and 5.6 d at the sandy and silly stations, respectively. The transfer of carbon from microphytobenthos to benthic consumers was estimated from the appearance of C-13 in bacterial biomarkers, handpicked nematodes, and macrofauna. The incorporation of C-13 into bacterial biomass was quantified by carbon isotope analysis of polar lipid derived fatty acids specific for bacteria. The bacterial polar lipid-derived fatty acids (i14:0, i15:0, a15:0, i16:0, and 18:1 omega 7c) showed rapid, significant transfer from benthic algae to bacteria with maximum labeling after 1 d. Nematodes became enriched after 1 h, and C-13 assimilation increased until day 3. Microphytobenthos carbon entered all heterotrophic components in proportion to heterotrophic biomass distribution (bacteria > macrofauna > meiofauna). Our results indicate a central role for microphytobenthos in moderating carbon flow in coastal sediments. [KEYWORDS: Water marine habitats; microbenthic communities; westerschelde estuary; microbial biomass; epipelic diatoms; ecological role; organic-matter; grazing rates; chlorophyll-a; secret garden]
TL;DR: Comparing the QL of a wide range of chronic disease patients found that patients who were older, female, had a low level of education, were not living with a partner, and had at least one comorbid condition, in general, reported the poorest level of QL.
TL;DR: 5-FC is a synthetic antimycotic compound that has no intrinsic antifungal capacity, but after it has been taken up by susceptible fungal cells, it is converted into 5-fluorouracil (5-FU), which is further converted to metabolites that inhibit fungal RNA and DNA synthesis.
Abstract: Flucytosine (5-FC) is a synthetic antimycotic compound, first synthesized in 1957. It has no intrinsic antifungal capacity, but after it has been taken up by susceptible fungal cells, it is converted into 5-fluorouracil (5-FU), which is further converted to metabolites that inhibit fungal RNA and DNA synthesis. Monotherapy with 5-FC is limited because of the frequent development of resistance. In combination with amphotericin B, 5-FC can be used to treat severe systemic mycoses, such as cryptococcosis, candidosis, chromoblastomycosis and aspergillosis. Recently, 5-FC has been combined with newer azole antifungal agents; it also plays an important role in a new approach to the treatment of cancer. The severe side effects of 5-FC include hepatotoxicity and bone-marrow depression. In most patients, these side effects are concentration dependent, predictable, possibly avoidable with close monitoring to maintain 5-FC concentrations at <100 mg/L, and reversible with drug discontinuation or reduction of dose. 5-FC is well absorbed after oral administration, penetrates into body tissues well and is excreted mainly by the kidneys. In renal failure, major dose adjustments have to be made. The most important drug interaction of 5-FC occurs with concomitant administration of 5-FC and nephrotoxic drugs, especially amphotericin B. Owing to the crucial role of glomerular filtration in 5-FC elimination, drugs that impair this mechanism will decrease the elimination of 5-FC and thus prolong its half-life.
TL;DR: In this paper, the authors discuss the role played by negative affectivity (NA) in the job stress process and demonstrate that it should not just be considered a bias in need of statistical control.
Abstract: In 1987 Watson, Pennebaker, and Folger wrote an in uential paper in which they noted the potential importance of negative aectivity (NA) in job stress research, going so far as to suggest the provocative hypothesis that NA biased self-reports of most job stressors (and other measures of work conditions) and job strains. A number of concerned researchers, noting correlations between NA and other variables, have recommended that we statistically control for NA bias in general stress (McCrae, 1990) and job stress (e.g., Brief et al., 1988; Payne, 1988) studies with some form of partialling. While we agree that aective dispositions are important, we disagree that it should become routine to treat them as bias factors to be statistically controlled. Although a number of researchers have noted possible non-bias or substantive roles for NA (e.g., Moyle, 1995; Schaubroeck, Ganster and Fox, 1992; Spector and O'Connell, 1994; Williams, Gavin and Williams, 1996), many researchers have started to routinely control for a NA bias in their studies. However, if indeed NA has a substantive role, one should not partial it as this can lead to removing the eects of the very variables one wishes to study. In this paper we will present arguments that partialling or related statistical techniques merely provide unrealistic hopes and illogical inferences in studying the potential biasing eect. Moreover, we will discuss the role played by NA in the job stress process and demonstrate that it should not just be considered a bias in need of statistical control. Rather NA can play a variety of substantive roles in the job stress process.
TL;DR: Allergens have no characteristic structural features other than that they need to be able to reach (and stimulate) immune cells and mast cells, and within this constraint, any antigen may be allergenic, particularly if it avoids activation of T(H)2-suppressive mechanisms.
Abstract: One of the major challenges of molecular allergy is to predict the allergenic potential of a protein, particularly in novel foods. Two aspects have to be distinguished: immunogenicity and cross-reactivity. Immunogenicity reflects the potential of a protein to induce IgE antibodies, whereas cross-reactivity is the reactivity of (usually preexisting) IgE antibodies with the target protein. In addition to these two issues, the relation between IgE-binding potential and clinical symptoms is of interest. This is influenced by physical properties (eg, stability and size) and immunologic properties (affinity and epitope valence). Discussions on immunogenicity and cross-reactivity of allergens rely on the establishment of structural similarities and differences among allergens and between allergens and nonallergens. For comparisons between the 3-dimensional protein folds, the representation as 2-dimensional proximity plots provides a convenient visual aid. Analysis of approximately 40 allergenic proteins (or parts of these proteins), of which the protein folds are either known or can be predicted on the basis of homology, indicates that most of these can be classified into 4 structural families: (1) antiparallel beta-strands: the immunoglobulin-fold family (grass group 2, mite group 2), serine proteases (mite group 3, 6, and 9), and soybean-type trypsin inhibitor (Ole e 1, grass group 11); (2) antiparallel beta-sheets intimately associated with one or more alpha-helices: tree group 1, lipocalin, profilin, aspartate protease (cockroach group 2); (3) (alpha+beta) structures, in which the alpha- and beta-structural elements are not intimately associated: mite group 1, lysozyme/lactalbumin, vespid group 5; and (4) alpha-helical: nonspecific lipid transfer protein, seed 2S protein, insect hemoglobin, fish parvalbumin, pollen calmodulin, mellitin from bee venom, Fel d 1 chain 1, serum albumin. Allergens with parallel beta-strands (in combination with an alpha-helix linking the two strands, a motif commonly found in, for example, nucleotide-binding proteins) seem to be underrepresented. The conclusion is that allergens have no characteristic structural features other than that they need to be able to reach (and stimulate) immune cells and mast cells. Within this constraint, any antigen may be allergenic, particularly if it avoids activation of T(H)2-suppressive mechanisms (CD8 cells and T(H)1 cells).
TL;DR: This paper conducted a meta-analysis of studies on overeducation and undereducation in the labor market and found that of the four different definitions of OO distinguished in the literature, only the one based on variation in years of education within occupational groups appears to yield significantly lower than average rates of oO.
TL;DR: A systematic review of randomized controlled trials was performed in this article to evaluate the effectiveness of exercise therapy for low back pain with regard to pain intensity, functional status, overall improvement, and return to work.
Abstract: Study design A systematic review of randomized controlled trials was performed. Summary of background data Exercise therapy is a widely used treatment for low back pain. Objectives To evaluate the effectiveness of exercise therapy for low back pain with regard to pain intensity, functional status, overall improvement, and return to work. Methods The Cochrane Controlled Trials Register, Medline, Embase, PsycLIT, and reference lists of articles were searched. Randomized trials testing all types of exercise therapy for subjects with nonspecific low back pain with or without radiation into the legs were included. Two reviewers independently extracted data and assessed trial quality. Because trials were considered heterogeneous with regard to study populations, interventions, and outcomes, it was decided not to perform a meta-analysis, but to summarize the results using a rating system of four levels of evidence: strong, moderate, limited, or none. Results In this review, 39 trials were identified. There is strong evidence that exercise therapy is not more effective for acute low back pain than inactive or other active treatments with which it has been compared. There is conflicting evidence on the effectiveness of exercise therapy compared with inactive treatments for chronic low back pain. Exercise therapy was more effective than usual care by the general practitioner and just as effective as conventional physiotherapy for chronic low back pain. Conclusions The evidence summarized in this systematic review does not indicate that specific exercises are effective for the treatment of acute low back pain. Exercises may be helpful for patients with chronic low back pain to increase return to normal daily activities and work.
TL;DR: A disulfide bond is introduced between the C-terminal region of gp120 and the immunodominant segment of the gp41 ectodomain, producing a properly folded envelope glycoprotein complex which has antigenic properties which resemble those of the virion-associated complex.
Abstract: The few antibodies that can potently neutralize human immunodeficiency virus type 1 (HIV-1) recognize the limited number of envelope glycoprotein epitopes exposed on infectious virions. These native envelope glycoprotein complexes comprise three gp120 subunits noncovalently and weakly associated with three gp41 moieties. The individual subunits induce neutralizing antibodies inefficiently but raise many nonneutralizing antibodies. Consequently, recombinant envelope glycoproteins do not elicit strong antiviral antibody responses, particularly against primary HIV-1 isolates. To try to develop recombinant proteins that are better antigenic mimics of the native envelope glycoprotein complex, we have introduced a disulfide bond between the C-terminal region of gp120 and the immunodominant segment of the gp41 ectodomain. The resulting gp140 protein is processed efficiently, producing a properly folded envelope glycoprotein complex. The association of gp120 with gp41 is now stabilized by the supplementary intermolecular disulfide bond, which forms with approximately 50% efficiency. The gp140 protein has antigenic properties which resemble those of the virion-associated complex. This type of gp140 protein may be worth evaluating for immunogenicity as a component of a multivalent HIV-1 vaccine.
TL;DR: In this paper, the formation of group norms in computer-mediated communication (CMC) was examined among students who used e-mail as part of a course and a network analysis of group structures revealed that content and form of communication is normative, group norms defining communication patterns within groups, conformity to group norms increases over time, and communication outside the group is governed by different social norms.
Abstract: The formation of group norms in computer-mediated communication (CMC) was examined among students who used e-mail as part of a course. A network analysis of group structures revealed that (a) content and form of communication is normative, group norms defining communication patterns within groups, (b) conformity to group norms increases over time, (c) communication outside the group is governed by different social norms. Results show that norms prescribing a particular use of technology are socially constructed over time at the level of locally defined groups and also show that the influence of these norms is limited to the boundaries of the group. It is concluded that the process of social construction is restrained by social identities that become salient over the course of interaction via CMC. These findings complement experimental evidence that stresses the importance of normative influence in CMC.