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Institution

University of Hamburg

EducationHamburg, Germany
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.


Papers
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Journal ArticleDOI
TL;DR: It is reported that, surprisingly, key NOB of many ecosystems (Nitrospira) convert urea, an important ammonia source in nature, to ammonia and CO2, leading to a reciprocal feeding interaction of nitrifiers.
Abstract: Nitrospira are a diverse group of nitrite-oxidizing bacteria and among the environmentally most widespread nitrifiers. However, they remain scarcely studied and mostly uncultured. Based on genomic and experimental data from Nitrospira moscoviensis representing the ubiquitous Nitrospira lineage II, we identified ecophysiological traits that contribute to the ecological success of Nitrospira. Unexpectedly, N. moscoviensis possesses genes coding for a urease and cleaves urea to ammonia and CO2. Ureolysis was not observed yet in nitrite oxidizers and enables N. moscoviensis to supply ammonia oxidizers lacking urease with ammonia from urea, which is fully nitrified by this consortium through reciprocal feeding. The presence of highly similar urease genes in Nitrospira lenta from activated sludge, in metagenomes from soils and freshwater habitats, and of other ureases in marine nitrite oxidizers, suggests a wide distribution of this extended interaction between ammonia and nitrite oxidizers, which enables nitrite-oxidizing bacteria to indirectly use urea as a source of energy. A soluble formate dehydrogenase lends additional ecophysiological flexibility and allows N. moscoviensis to use formate, with or without concomitant nitrite oxidation, using oxygen, nitrate, or both compounds as terminal electron acceptors. Compared with Nitrospira defluvii from lineage I, N. moscoviensis shares the Nitrospira core metabolism but shows substantial genomic dissimilarity including genes for adaptations to elevated oxygen concentrations. Reciprocal feeding and metabolic versatility, including the participation in different nitrogen cycling processes, likely are key factors for the niche partitioning, the ubiquity, and the high diversity of Nitrospira in natural and engineered ecosystems.

392 citations

Proceedings ArticleDOI
01 Aug 2015
TL;DR: This paper introduces several probabilistic techniques to classify app reviews into four types: bug reports, feature requests, user experiences, and ratings, and conducts a series of experiments to compare the accuracy of the techniques and compared them with simple string matching.
Abstract: App stores like Google Play and Apple AppStore have over 3 Million apps covering nearly every kind of software and service. Billions of users regularly download, use, and review these apps. Recent studies have shown that reviews written by the users represent a rich source of information for the app vendors and the developers, as they include information about bugs, ideas for new features, or documentation of released features. This paper introduces several probabilistic techniques to classify app reviews into four types: bug reports, feature requests, user experiences, and ratings. For this we use review metadata such as the star rating and the tense, as well as, text classification, natural language processing, and sentiment analysis techniques. We conducted a series of experiments to compare the accuracy of the techniques and compared them with simple string matching. We found that metadata alone results in a poor classification accuracy. When combined with natural language processing, the classification precision got between 70–95% while the recall between 80–90%. Multiple binary classifiers outperformed single multiclass classifiers. Our results impact the design of review analytics tools which help app vendors, developers, and users to deal with the large amount of reviews, filter critical reviews, and assign them to the appropriate stakeholders.

392 citations

Journal ArticleDOI
Felix R. Day1, Deborah J. Thompson1, Hannes Helgason2, Hannes Helgason3  +241 moreInstitutions (67)
TL;DR: In this article, the authors used 1000 Genomes Project-imputed genotype data in up to ∼370,000 women to identify 389 independent signals (P < 5 × 10-8) for age at menarche, a milestone in female pubertal development.
Abstract: The timing of puberty is a highly polygenic childhood trait that is epidemiologically associated with various adult diseases. Using 1000 Genomes Project-imputed genotype data in up to ∼370,000 women, we identify 389 independent signals (P < 5 × 10-8) for age at menarche, a milestone in female pubertal development. In Icelandic data, these signals explain ∼7.4% of the population variance in age at menarche, corresponding to ∼25% of the estimated heritability. We implicate ∼250 genes via coding variation or associated expression, demonstrating significant enrichment in neural tissues. Rare variants near the imprinted genes MKRN3 and DLK1 were identified, exhibiting large effects when paternally inherited. Mendelian randomization analyses suggest causal inverse associations, independent of body mass index (BMI), between puberty timing and risks for breast and endometrial cancers in women and prostate cancer in men. In aggregate, our findings highlight the complexity of the genetic regulation of puberty timing and support causal links with cancer susceptibility.

392 citations

Journal ArticleDOI
TL;DR: In this article, the authors consider specific additive decompositions d = d 1 + … + d n of metrics, defined on a finite set X (where a metric may give distance zero to pairs of distinct points).

392 citations

Journal ArticleDOI
01 Nov 2006-Pain
TL;DR: The hypothesis that ongoing nociception is associated with cortical and subcortical reorganisation on a structural level, which may play an important role in the process of the chronification of pain, is supported.
Abstract: Although chronic back pain is one of the most frequent reasons for permanent impairment in people under 65, the neurobiological mechanisms of chronification remain vague. Evidence suggests that cortical reorganisation, so-called functional plasticity, may play a role in chronic back pain patients. In the search for the structural counterpart of such functional changes in the CNS, we examined 18 patients suffering from chronic back pain with voxel-based morphometry and compared them to 18 sex and age matched healthy controls. We found a significant decrease of gray matter in the brainstem and the somatosensory cortex. Correlation analysis of pain unpleasantness and the intensity of pain on the day of scanning revealed a strong negative correlation (i.e. a decrease in gray matter with increasing unpleasantness/increasing intensity of pain) in these areas. Additionally, we found a significant increase in gray matter bilaterally in the basal ganglia and the left thalamus. These data support the hypothesis that ongoing nociception is associated with cortical and subcortical reorganisation on a structural level, which may play an important role in the process of the chronification of pain.

392 citations


Authors

Showing all 46072 results

NameH-indexPapersCitations
Rudolf Jaenisch206606178436
Bruce M. Psaty1811205138244
Stefan Schreiber1781233138528
Chris Sander178713233287
Dennis J. Selkoe177607145825
Daniel R. Weinberger177879128450
Ramachandran S. Vasan1721100138108
Bradley Cox1692150156200
Anders Björklund16576984268
J. S. Lange1602083145919
Hannes Jung1592069125069
Andrew D. Hamilton1511334105439
Jongmin Lee1502257134772
Teresa Lenz1501718114725
Stefanie Dimmeler14757481658
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023282
2022817
20215,784
20205,491
20194,994
20184,587