Shedding Light on the Galaxy Luminosity Function

From as early as the 1930s, astronomers have tried to quantify the statistical nature of the evolution and large-scale structure of galaxies by studying their luminosity distribution as a function of redshift - known as the galaxy luminosity function (LF). Accurately constructing the LF remains a popular and yet tricky pursuit in modern observational cosmology where the presence of observational selection effects due to e.g. detection thresholds in apparent magnitude, colour, surface brightness or some combination thereof can render any given galaxy survey incomplete and thus introduce bias into the LF. Over the last seventy years there have been numerous sophisticated statistical approaches devised to tackle these issues; all have advantages -- but not one is perfect. This review takes a broad historical look at the key statistical tools that have been developed over this period, discussing their relative merits and highlighting any significant extensions and modifications. In addition, the more generalised methods that have emerged within the last few years are examined. These methods propose a more rigorous statistical framework within which to determine the LF compared to some of the more traditional methods. I also look at how photometric redshift estimations are being incorporated into the LF methodology as well as considering the construction of bivariate LFs. Finally, I review the ongoing development of completeness estimators which test some of the fundamental assumptions going into LF estimators and can be powerful probes of any residual systematic effects inherent magnitude-redshift data.Comment: 95 pages, 23 figures, 3 tables. Now published in The Astronomy & Astrophysics Review. This version: bring in line with A&AR format requirements, also minor typo corrections made, additional citations and higher rez images adde

The Era of Human-Induced Diseases

peer reviewe

First ciguatera outbreak in Germany in 2012

Im November 2012 traten in Deutschland nach dem Verzehr von importiertem Tropenfisch (Lutjanus spp.) 23 Vergiftungen mit der für Ciguatera typischen Kombination gastrointestinaler und neurologischer Symptome auf. Anhand eines Fragebogens wurden der Krankheitsverlauf und Informationen zum Fischverzehr erfasst. Alle Patienten litten an der pathognomonischen Kaltallodynie. Zwei Patienten hatten schwere Symptome, die anderen Fälle verliefen mittelschwer. Im Rahmen des 3‑Jahres-Follow-up berichteten sieben Patienten von länger als ein Jahr anhaltenden Parästhesien. Bei zwei Patienten konnten fast drei Jahre anhaltende Neuropathien detailliert dokumentiert werden. Die Patienten können acht Clustern in sieben deutschen Städten zugeordnet werden. Ein weiteres potenzielles Cluster wurde durch den geglückten Rückruf bereits verkaufter, Ciguatoxin-haltiger Ware verhindert. Drei Cluster wurden durch den Nachweis von Ciguatoxin in Rückruf- und Verdachtsproben objektiviert. Eine Hochrechnung auf der Basis Ciguatoxin-haltiger Proben ergab etwa 20 verhinderte Erkrankungsfälle. Im Rahmen der Ausbruchsaufklärung wurden irrtümlich widersprüchliche Kennzeichnungen auf den Lieferpapieren hinsichtlich der an den Einzelhandel gelieferten Fischart sowie deren Fanggebiet bekannt. Durch die uneinheitliche Vorgehensweise bei den Meldungen an Giftinformationszentren, Veterinär- und Gesundheitsämter erwiesen sich die Erfassung der Fälle und die Aufklärung des Ciguatera-Ausbruchs als schwierig. Vielen Ärzten in Deutschland ist das durch Tropenfisch verursachte Krankheitsbild bislang unzureichend bekannt. Das Auftreten weiterer Ausbrüche in den Folgejahren unterstreicht die zunehmende Bedeutung von Ciguatera in Deutschland.In November 2012, 23 cases of ciguatera with typical combinations of gastrointestinal and neurological symptoms occurred in Germany after consumption of imported tropical fish (Lutjanus spp.). A questionnaire was used to gather information on the disease course and fish consumption. All patients suffered from pathognomonic cold allodynia. Aside from two severe courses of illness, all other cases showed symptoms of moderate intensity. During a three-year follow-up, seven patients reported prolonged paresthesia for more than one year. Two of them reported further neuropathies over almost three years. This is the first time that long-term persistence of symptoms has been documented in detail. Outbreak cases were allocated to eight clusters in seven German cities. A further cluster was prevented by the successful recall of ciguatoxic fish. Three clusters were confirmed by the detection of ciguatoxin in samples of suspicious and recalled fish. An extrapolation on the basis of ciguatoxic samples revealed twenty prevented cases of ciguatera. Further officially unknown cases should be assumed. During the outbreak investigations, inadvertently falsely labelled fish species and fishing capture areas on import and retail level documents were observed. The ascertainment of cases and the outbreak investigations proved to be difficult due to inconsistent case reports to poisons centers, local health and veterinary authorities. In Germany, many physicians are unaware of the disease pattern of ciguatera and the risks caused by tropical fish. The occurrence of further outbreaks during the following years emphasizes the increasing significance of ciguatera in Germany

Optimization of Translation Profiles Enhances Protein Expression and Solubility

mRNA is translated with a non-uniform speed that actively coordinates co-translational folding of protein domains. Using structure-based homology we identified the structural domains in epoxide hydrolases (EHs) and introduced slow-translating codons to delineate the translation of single domains. These changes in translation speed dramatically improved the solubility of two EHs of metagenomic origin in Escherichia coli. Conversely, the importance of transient attenuation for the folding, and consequently solubility, of EH was evidenced with a member of the EH family from Agrobacterium radiobacter, which partitions in the soluble fraction when expressed in E. coli. Synonymous substitutions of codons shaping the slow-transiting regions to fast-translating codons render this protein insoluble. Furthermore, we show that low protein yield can be enhanced by decreasing the free folding energy of the initial 5'-coding region, which can disrupt mRNA secondary structure and enhance ribosomal loading. This study provides direct experimental evidence that mRNA is not a mere messenger for translation of codons into amino acids but bears an additional layer of information for folding, solubility and expression level of the encoded protein. Furthermore, it provides a general frame on how to modulate and fine-tune gene expression of a target protein