Impact of nitrate addition on biofilm properties and activities in rising main sewers

Anaerobic sewer biofilm is a composite of many different microbial populations, including sulfate reducing bacteria (SRB), methanogens and heterotrophic bacteria. Nitrate addition to sewers in an attempt to control hydrogen sulfide concentrations affects the behaviour of these populations, which in turn impacts on wastewater characteristics. Experiments were carried out on a laboratory reactor system simulating a rising main to determine the impact of nitrate addition on the microbial activities of anaerobic sewer biofilm. Nitrate was added to the start of the rising main during sewage pump cycles at a concentration of 30 mg-N L(-1) for over 5 months. While it reduced sulfide levels at the outlet of the system by 66%, nitrate was not toxic or inhibitory to SRB activity and did not affect the dominant SRB populations in the biofilm. Long-term nitrate addition in fact stimulated additional SRB activity in downstream biofilm. Nitrate addition also stimulated the activity of nitrate reducing, sulfide oxidizing bacteria that appeared to be primarily responsible for the prevention of sulfide build up in the wastewater in the presence of nitrate. A short adaptation period of three to four nitrate exposure events (approximately 10 h) was required to stimulate biological sulfide oxidation, beyond which no sulfide accumulation was observed under anoxic conditions. Nitrate addition effectively controlled methane concentrations in the wastewater. The nitrate uptake rate of the biofilm increased with repeated exposure to nitrate, which in turn increased the consumption of biodegradable COD in the wastewater. These results provide a comprehensive understanding of the impact of nitrate addition on wastewater composition and sewer biofilm microbial activities, which will facilitate optimization of nitrate dosing for effective sulfide control in rising main sewers.

Impact of a positive family history on diagnosis, management, and survival of breast cancer: different effects across socio-economic groups

BACKGROUND

This study aims to investigate whether increased awareness of breast cancer, due to a positive family history (FH), reduces diagnostic, therapeutic, and survival differences between women of low versus high socio-economic status (SES).

METHODS

All breast cancer patients registered between 1990 and 2005 at the population-based Geneva Cancer Registry were included. With multivariate logistic and Cox regression analysis, we estimated the impact of SES and FH on method of detection, treatment, and mortality from breast cancer.

RESULTS

SES discrepancies in method of detection and suboptimal treatment, as seen among women without a FH, disappeared in the presence of a positive FH. SES differences in stage and survival remained regardless of the presence of a positive FH. Overall, positive FH was associated with better survival. This effect was the strongest in women of high SES (age-adjusted Hazard Ratio [HR(ageadj)] 0.54 [0.3-1.0]) but less pronounced in women of middle (0.77 [0.6-1.0]), and absent in women of low SES (0.80 [0.5-1.2]).

CONCLUSION

A positive FH of breast cancer may reduce SES differences in access to screening and optimal treatment. However, even with better access to early detection and optimal treatment, women of low SES have higher risks of death from their disease than those of high SES.

A protein encoded by a new family of mobile elements from Euryarchaea exhibits three domains with novel folds

We present here the 2.6A resolution crystal structure of the pT26-6p protein, which is encoded by an ORF of the plasmid pT26-2, recently isolated from the hyperthermophilic archaeon, Thermococcus sp. 26,2. This large protein is present in all members of a new family of mobile elements that, beside pT26-2 include several virus-like elements integrated in the genomes of several Thermococcales and Methanococcales (phylum Euryarchaeota). Phylogenetic analysis suggested that this protein, together with its nearest neighbor (organized as an operon) have coevolved for a long time with the cellular hosts of the encoding mobile element. As the sequences of the N and C-terminal regions suggested a possible membrane association, a deletion construct (739 amino acids) was used for structural analysis. The structure consists of two very similar beta-sheet domains with a new topology and a five helical bundle C-terminal domain. Each of these domains corresponds to a unique fold that has presently not been found in cellular proteins. This result supports the idea that proteins encoded by plasmid and viruses that have no cellular homologues could be a reservoir of new folds for structural genomic studies.

Do we need gastric acid?

Evidence from comparative anatomy and physiology studies indicates that gastric acid secretion developed during the evolution of vertebrates approximately 350 million years ago. The cellular mechanisms that produce gastric acid have been conserved over the millennia and therefore proton pump inhibitors have pharmacological effects in almost all relevant species. These observations suggest that gastric acid provides an important selective advantage; however, in modern-day humans the need for gastric acid can be questioned in light of the widespread use of safe and effective pharmacologic acid suppression. The Kandahar Working Group addressed questions concerning the need, production and effects of gastric acid, specifically: (1) motility in the upper gastrointestinal (GI) tract; (2) neuroendocrine factors; (3) digestive and mucosal processes; (4) microbiology, and (5) central processes and psychological involvement. We addressed each topic with the individual models available to answer our questions including animal versus human studies, pharmacologic, surgical as well as pathophysiologic states of acid suppression.

Experiment LEND of the NASA Lunar Reconnaissance Orbiter for high-resolution mapping of neutron emission of the Moon

The scientific objectives of neutron mapping of the Moon are presented as 3 investigation tasks of NASA's Lunar Reconnaissance Orbiter mission. Two tasks focus on mapping hydrogen content over the entire Moon and on testing the presence of water-ice deposits at the bottom of permanently shadowed craters at the lunar poles. The third task corresponds to the determination of neutron contribution to the total radiation dose at an altitude of 50 km above the Moon. We show that the Lunar Exploration Neutron Detector (LEND) will be capable of carrying out all 3 investigations. The design concept of LEND is presented together with results of numerical simulations of the instrument's sensitivity for hydrogen detection. The sensitivity of LEND is shown to be characterized by a hydrogen detection limit of about 100 ppm for a polar reference area with a radius of 5 km. If the presence of ice deposits in polar "cold traps" is confirmed, a unique record of many millions of years of lunar history would be obtained, by which the history of lunar impacts could be discerned from the layers of water ice and dust. Future applications of a LEND-type instrument for Mars orbital observations are also discussed.

Flow and regulatory compatibility: an experimental approach to the flow model of intrinsic motivation

The authors propose that the experience of flow (Csikszentmihalyi, 2000) as reflected in the deep involvement in an activity perceived as intrinsically rewarding represents a regulatory compatibility experience. The research addresses the notion that the compatibility of critical person (e.g., skills) and environmental factors (e.g., demands) involved in a given activity elicits subjective experiences that render the respective activity rewarding. Two studies are reported that investigate the consequences of compatibility of skills and task demands during task engagement. Departing from correlational research, the present studies employ a newly developed experimental paradigm to document the causal impact of such a skills/demands compatibility on the emergence of flow. Experiment 2 revealed that individuals characterized by a strong habitual action-orientation were most sensitive to the manipulation of the skills-demands compatibility.

The role of calcitonin and alpha-calcitonin gene-related peptide in bone formation

The Calca gene encodes two polypeptides, calcitonin (CT) and alpha-calcitonin gene-related peptide (alpha-CGRP), generated through alternative splicing. While CT, a hormone mainly produced by thyroidal C cells, has been described as a major regulator of bone resorption, alpha-CGRP, a neuropeptide expressed in the cells of the central and peripheral nervous system, is mostly known as a regulator of vascular tone. Surprisingly, the generation and skeletal analyses of two mouse deficiency models has recently uncovered a physiological function for both peptides in the regulation of bone formation. In the first model, where the replacement of exons 2-5 of the Calca gene resulted in the combined deficiency of CT and alpha-CGRP, an increased bone formation rate (BFR) was observed, whereas decreased BFR was found in the second model, where the introduction of a translational termination codon into exon 5 of the Calca gene resulted in the specific absence of alpha-CGRP.

Continuous measurement of dissolved sulfide in sewer systems

Sulfides are particularly problematic in the sewage industry. Hydrogen sulfide causes corrosion of concrete infrastructure, is dangerous at high concentrations and is foul smelling at low concentrations. Despite the importance of sulfide monitoring there is no commercially available system to quantify sulfide in waste water. In this article we report on our use of an in situ spectrometer to quantify bisulfide in waste water and additional analysis with a pH probe to calculate total dissolved sulfide. Our results show it is possible to use existing commercially available and field proven sensors to measure sulfide to mg/l levels continuously with little operator intervention and no sample preparation.

Microbial fuel cell cathodes: from bottleneck to prime opportunity?

Microbial fuel cells that can generate energy out of wastewaters are close to pilot scale testing. As such, MFC technology is complementary to methane generation due to the possibility to rapidly convert organic acids, polish effluents and work at low substrate concentrations. The main bottleneck perceived at the moment is the cathodic electron transfer. A variety of catalysts has been investigated for the direct transfer of electrons from the cathode to oxygen in the air. Overlooked in this context were bacteria. Bacteria could indeed be worthwhile to replace chemical catalysts. Moreover, their versatility enables us to not only target at oxygen, but also at nitrous oxides and contaminants as possible drivers of electricity generation, nutrient removal and bioremediation. This paper addresses several recent developments in MFC cathode research, and demonstrates that energy generation is but an aspect of this versatile technology.

When Negative Stereotypic Expectancies Turn Into Challenge or Threat: The Moderating Role of Regulatory Focus

The impact of negative stereotypic expectations on men’s verbal performance was investigated in an experimental study. The study was designed to test a theoretical perspective that relates self-regulatory processes as postulated in Regulatory Focus Theory (Higgins, 1998) to stereotypic expectancy effects on test performance as previously documented in research on stereotype threat. It is argued that negative stereotypic expectancies (e.g., “Men are bad at verbal tasks”) are more likely to result in a threat experience and poorer test performance when a prevention focus and in turn a special sensitivity to potential negative outcomes is activated whereas negative stereotypic expectancies are more likely to result in a challenge experience and better test performance when a promotion focus has been induced. The results indicate that expectancy effects on test performance are indeed moderated by the mode of self-regulation activated in the testing situation.

Empfehlungen zur Anorektalen Manometrie im Erwachsenenalter

This document contains the guidelines of the German Societies of Neurogastroenterology and Motility, Gastroenterology (committee for proctology), Abdominal Surgery (coloproctology working group), and Coloproctology for anorectal manometry in adults. Recommendations are given about technical notes, study preparation (equipment; patient), technique for performing manometry and data analysis, reproducibility, and indications. Minimum standards for anorectal manometry are measurement of resting and squeeze pressure, testing of rectoanal inhibitory reflex, determination of rectal sensation (first perception and urge), and calculation of rectal compliance. Anorectal manometry is indicated in patients with fecal incontinence and constipation in the context of a structured programme.