Humboldt University of Berlin

About: Humboldt University of Berlin is a education organization based out in Berlin, Germany. It is known for research contribution in the topics: Population & Medicine. The organization has 33671 authors who have published 61781 publications receiving 1908102 citations. The organization is also known as: Humboldt-Universität zu Berlin & Universitas Humboldtiana Berolinensis.

E-privacy in 2nd generation E-commerce: privacy preferences versus actual behavior

Abstract: As electronic commerce environments become more and more interactive, privacy is a matter of increasing concern. Many surveys have investigated households' privacy attitudes and concerns, revealing a general desire among Internet users to protect their privacy. To complement these questionnaire-based studies, we conducted an experiment in which we compared self-reported privacy preferences of 171 participants with their actual disclosing behavior during an online shopping episode. Our results suggest that current approaches to protect online users' privacy, such as EU data protection regulation or P3P, may face difficulties to do so effectively. This is due to their underlying assumption that people are not only privacy conscious, but will also act accordingly. In our study, most individuals stated that privacy was important to them, with concern centering on the disclosure of different aspects of personal information. However, regardless of their specific privacy concerns, most participants did not live up to their self-reported privacy preferences. As participants were drawn into the sales dialogue with an anthropomorphic 3-D shopping bot, they answered a majority of questions, even if these were highly personal. Moreover, different privacy statements had no effect on the amount of information disclosed; in fact, the mentioning of EU regulation seemed to cause a feeling of 'false security'. The results suggest that people appreciate highly communicative EC environments and forget privacy concerns once they are 'inside the Web'.

Changing the antigen binding specificity by single point mutations of an anti-p24 (HIV-1) antibody.

Abstract: The murine mAb CB4-1 raised against p24 (HIV-1) recognizes a linear epitope of the HIV-1 capsid protein Additionally, CB4-1 exhibits cross-reactive binding to epitope-homologous peptides and polyspecific reactions to epitope nonhomologous peptides Crystal structures demonstrate that the epitope peptide (e-pep) and the nonhomologous peptides adopt different conformations within the binding region of CB4-1 Site-directed mutagenesis of the fragment variable (Fv) region was performed using a single-chain (sc)Fv construct of CB4-1 to analyze binding contributions of single amino acid side chains toward the e-pep and toward one epitope nonhomologous peptide The mutations of Ab amino acid side chains, which are in direct contact with the Ag, show opposite influences on the binding of the two peptides Whereas the affinity of the e-pep to the CB4-1 scFv mutant heavy chain variable region Tyr32Ala is decreased 250-fold, the binding of the nonhomologous peptide remains unchanged In contrast, the mutation light chain variable region Phe94Ala reduces the affinity of the nonhomologous peptide 10-fold more than it does for the e-pep Thus, substantial changes in the specificity can be observed by single amino acid exchanges Further characterization of the scFv mutants by substitutional analysis of the peptides demonstrates that the effect of a mutation is not restricted to contact residues This method also reveals an inverse compensatory amino acid exchange for the nonhomologous peptide which increases the affinity to the scFv mutant light chain variable region Phe94Ala up to the level of the e-pep affinity to the wild-type scFv

Land management and land-cover change have impacts of similar magnitude on surface temperature

Abstract: The direct effects of land-cover change on surface climate are increasingly well understood, but fewer studies have investigated the consequences of the trend towards more intensive land management practices. Now, research investigating the biophysical effects of temperate land-management changes reveals a net warming effect of similar magnitude to that driven by changing land cover. Anthropogenic changes to land cover (LCC) remain common, but continuing land scarcity promotes the widespread intensification of land management changes (LMC) to better satisfy societal demand for food, fibre, fuel and shelter1. The biophysical effects of LCC on surface climate are largely understood2,3,4,5, particularly for the boreal6 and tropical zones7, but fewer studies have investigated the biophysical consequences of LMC; that is, anthropogenic modification without a change in land cover type. Harmonized analysis of ground measurements and remote sensing observations of both LCC and LMC revealed that, in the temperate zone, potential surface cooling from increased albedo is typically offset by warming from decreased sensible heat fluxes, with the net effect being a warming of the surface. Temperature changes from LMC and LCC were of the same magnitude, and averaged 2 K at the vegetation surface and were estimated at 1.7 K in the planetary boundary layer. Given the spatial extent of land management (42–58% of the land surface) this calls for increasing the efforts to integrate land management in Earth System Science to better take into account the human impact on the climate8.

Disk Instantons, Mirror Symmetry and the Duality Web

Abstract: We apply the methods recently developed for computation of type IIA disk instantons using mirror symmetry to a large class of D-branes wrapped over Lagrangian cycles of non-compact Calabi-Yau 3-folds. Along the way we clarify the notion of "flat coordinates" for the boundary theory. We also discover an integer IR ambiguity needed to define the quantum theory of D-branes wrapped over non-compact Lagrangian submanifolds. In the large N dual Chem-Simons theory, this ambiguity is mapped to the UV choice of the framing of the knot. In a type IIB dual description involving (p, q) 5-branes, disk instantons of type IIA get mapped to (p, q) string instantons. The M-theory lift of these results lead to computation of superpotential terms generated by M2 brane instantons wrapped over 3-cycles of certain manifolds of G 2 holonomy.