University of Hamburg

About: University of Hamburg is a education organization based out in Hamburg, Germany. It is known for research contribution in the topics: Population & Laser. The organization has 45564 authors who have published 89286 publications receiving 2850161 citations. The organization is also known as: Hamburg University.

Digitalization: Opportunity and Challenge for the Business and Information Systems Engineering Community

Abstract: The convergence of the so-called SMAC technologies – social, mobile, analytics, and cloud computing – has led to an unprecedented wave of digitalization that is currently fueling innovation in business and society. As digitalization is embracing all aspects of our private and professional lives, it is becoming a priority for managers and policymakers, and has made it into the headlines of newspapers, magazines, and practitioner conferences. This wave of digitalization is creating opportunities for the BISE community to engage in innovative research activities and to increase the discipline’s visibility. However, since BISE researchers have investigated the increasing exploitation and integration of digital technologies over several decades, they also naturally react with ambivalence when others claim that going digital is a new phenomenon.

Spectroscopy of electronic states in InSb quantum dots.

Abstract: We have realized arrays of quantum dots on InSb and observe intraband transitions between their discrete (zero-dimensional) electronic states with far-infrared magnetospectroscopy. In our devices, the number of electrons can be adjusted by a gate voltage and less than 5 electrons per dot are detectable.

Dynamic Distribution of Growth Rates within the Ensembles of Colloidal II−VI and III−V Semiconductor Nanocrystals as a Factor Governing Their Photoluminescence Efficiency

Abstract: The distribution of properties within ensembles of colloidally grown II-VI and III-V semiconductor nanocrystals was studied. A drastic difference in the photoluminescence efficiencies of size-selected fractions was observed for both organometallically prepared CdSe and InAs colloids and for CdTe nanocrystals synthesized in aqueous medium, indicating a general character of the phenomenon observed. The difference in the photoluminescence efficiencies is attributed to different averaged surface disorder of the nanocrystals originating from the Ostwald ripening growth mechanism when larger particles in the ensemble grow at the expense of dissolving smaller particles. At any stage of growth, only a fraction of particles within the ensemble of growing colloidal nanocrystals has the most perfect surface and, thus, shows the most efficient photoluminescence. This is explained by a theoretical model describing the evolution of an ensemble of nanocrystals in a colloidal solution. In an ensemble of growing nanocrystals, the fraction of particles with the highest photoluminescence corresponds to the particle size having nearly zero average growth rate. The small average growth rate leads to the lowest possible degree of surface disorder at any given reaction conditions.

Voltage-dependent electrogenic chloride/proton exchange by endosomal CLC proteins.

Abstract: Eukaryotic members of the CLC gene family function as plasma membrane chloride channels, or may provide neutralizing anion currents for V-type H+-ATPases that acidify compartments of the endosomal/lysosomal pathway1. Loss-of-function mutations in the endosomal protein ClC-5 impair renal endocytosis2 and lead to kidney stones3, whereas loss of function of the endosomal/lysosomal protein ClC-7 entails osteopetrosis4 and lysosomal storage disease5. Vesicular CLCs have been thought to be Cl- channels, in particular because ClC-4 and ClC-5 mediate plasma membrane Cl- currents upon heterologous expression6,7. Here we show that these two mainly endosomal CLC proteins instead function as electrogenic Cl-/H+ exchangers (also called antiporters), resembling the transport activity of the bacterial protein ClC-e1 (ref. 8), the crystal structure of which has already been determined9. Neutralization of a critical glutamate residue not only abolished the steep voltage-dependence of transport7, but also eliminated the coupling of anion flux to proton counter-transport. ClC-4 and ClC-5 may still compensate the charge accumulation by endosomal proton pumps, but are expected to couple directly vesicular pH gradients to Cl- gradients.

Estimates of the Damage Costs of Climate Change, Part II. Dynamic Estimates

Abstract: Monetised estimates of the impact of climate change are derived. Impacts are expressed as functions of climate change and 'vulnerability'. Vulnerability is measured by a series of indicators, such as per capita income, population above 65, and economic structure. Impacts are estimated for nine world regions, for the period 2000-2200, for agriculture, forestry, water resources, energy consumption, sea level rise, ecosystems, fatal vector- borne diseases, and fatal cardiovascular and respiratory disorders. Uncertainties are large, often including sign switches. In the short term, the estimated sensitivity of a sector to climate change is found to be the crucial parameter. In the longer term, the change in the vulnerability of the sector is often more important for the total impact. Impacts can be negative or positive, depending on the time, region, and sector one is looking at. Negative impacts tend to dominate in the later years and in the poorer regions.