Effect of sludge age on the bacterial diversity of bench scale sequencing batch reactors.

Sludge age or mean cell residence time (MCRT) plays a crucial role in design and operation of wastewater treatment plants. The change in performance, for example micropollutant removal, associated with changes in MCRT is often attributed to changes in microbial diversity. We operated four identical laboratory-scale sequencing batch reactors (two test and two control) in parallel for 212 days. Sludge age was decreased gradually (from 10.4to 2.6 days) in experimental reactors whereas it was kept constant (10.4 days) in control reactors. The reactor performance and biomass changed in a manner consistent with our understanding of the effect of sludge age on a reactors performance: the effluent quality and biomass declined with decreasing MCRT. The composition of the bacterial and ammonia-oxidizing bacterial communities in four reactors was analyzed using denaturing gradient gel electrophoresis (DGGE), and similarities in band patterns were measured using the Dice coefficient. The overall similarity between the communities in reactors run at different sludge ages was indistinguishable from the similarity in communities in reactors run at identical sludge ages. This was true for both the general bacterial communities and putative AOB communities. The number of detectable bands in DGGE profiles was also unaffected by sludge age (p approximately 0.5 in both cases). Initially, the detectable diversity of activated sludge communities in all four reactors clustered with time, regardless of their designation or sludge age; however, these clusters were only weakly supported by bootstrap analysis. However, after 135 days, a sludge age specific clustering was observed in the bacterial community but not the putative ammonia-oxidizing bacterial community. The mean self-similarity of each reactor decreased, variance increased, and the number of detectable bands in DGGE profiles decreased over time in all reactors. The changes observed with time are consistent with ecological drift. Sludge age has a subtler and slower effect than we anticipated. However, we postulate that sludge age may be more evident in the taxa occurring below the detection limit of DGGE. New sequencing technology may help us address this hypothesis

Three years follow-up of screen-detected diabetic and non-diabetic subjects: who is better off? The ADDITION Netherlands study

Abstract Background People with non-diabetic hyperglycaemia might be at risk of lacking adequate control for cardiovascular risk factors. Our aim was to determine the extent of health care utilization and provision in primary care and to evaluate the risk of cardiovascular disease in persons with an elevated risk score in a stepwise diabetes screening programme. Methods A total of 56,978 non-diabetic patients, aged 50–70 years, from 79 practices in the Netherlands were invited to participate in a screening programme starting with a questionnaire. Those with an elevated score, underwent further glucose testing. Screened participants with type 2 diabetes (n = 64), impaired glucose tolerance (IGT) (n = 62), impaired fasting glucose (IFG) (n = 86), and normal glucose tolerance (NGT) (n = 142) were compared after three years regarding use of medication, care provider encounters and occurrence of CVD. Results In all glucose regulation categories cardiovascular medication was prescribed more frequently during follow-up with the strongest increase in diabetic patients. Number of practice visits was higher in diabetic patients compared to those in the other categories. Glucose, lipids, and blood pressure were measured most frequently in diabetic patients. Numbers of cardiovascular events in participants with NGT, IFG, IGT and diabetes were 16.7, 32.6, 17.3 and 15.7 per 1,000 person-years (non significant), respectively. Conclusion After three years of follow-up, screened non-diabetic participants with an elevated risk score had cardiovascular event rates comparable with diabetic patients. Screened non-diabetic persons are at risk of lacking optimal control for cardiovascular risk factors while screen-detected diabetic patients were controlled adequately.</p

Effect of wastewater composition on archaeal population diversity

Distribution and occurrence of Archaea and methanogenic activity in a laboratory scale, completely mixed anaerobic reactor treating pharmaceutical wastewaters were investigated and associated with reactor performance. The reactor was initially seeded with anaerobic digester sludge from an alcohol distillery wastewater treatment plant and was subjected to a three step feeding strategy. The feeding procedure involved gradual transition from a glucose containing feed to a solvent stripped pharmaceutical wastewater and then raw pharmaceutical wastewater. During the start-up period, over 90% COD removal efficiency at an organic loading rate (OLR) of 6 kg COD m-3 d -1 was achieved with glucose feeding, and acetoclastic methanogenic activity was 336 ml CH4 gTVS-1 d-1. At the end of the primary loading, when the feed contained solvent stripped pharmaceutical wastewater at full composition, 71% soluble COD removal efficiency was obtained and acetoclastic methanogenic activity decreased to half of the rate under glucose feed (166 ml CH4 gTVS-1 d-1). At the end of secondary loading with 60% (w/v) raw pharmaceutical wastewater, COD removal dropped to zero and acetoclastic methanogenic activity fell to less than 10 ml CH4 gTVS-1 d-1. Throughout the course of the experiment, microbial community structure was monitored by DGGE analysis of 16S rRNA gene fragments. Five different archaeal taxa were identified and the predominant archaeal sequences belonged to methanogenic Archaea. Two of these showed greatest sequence identity with Methanobacterium formicicum and Methanosaeta concilii. The types of Archaea present changed little in response to changing feed composition but the relative contribution of different organisms identified in the archaeal DGGE profiles did change. \ua9 2005 Elsevier Ltd. All rights reserved

Gyllene snittet och geometriförståelse på gymnasiet

Abstrakt Examensarbete i matematik för lärare, Titel: Gyllene snittet och geometriförståelse på gymnasiet. Författare: Simon Larsson Termin och år: VT 2015 Kursansvarig institution: Matematiska Vetenskaper Handledare: Jonny Lindström Examinator: Laura Fainsilber Rapportnummer: Nyckelord: Matematik, geometri, gyllene snittet, matematiska begrepp, Van Hiele-nivåer, förståelse, inlärning. Syftet med mitt arbete är att utreda vad det gyllene snittet innebär, samtidigt som detta förhoppningsvis ger mig en grund för att senare i arbetslivet kunna använda mig av denna kunskap för att konstruera matematikuppgifter som dels innefattar den mystik som finns kring gyllene snittet, men även ta ut eleverna mer i verkligheten och genom gyllene snittet visa hur matematik dyker upp på oväntade platser omkring oss där deras förmåga att analysera geometri blir bättre. Speciellt som både matematik- och naturkunskapslärare är det av intresse för mig, då naturen är en vanlig plats där detta snitt dyker upp. Den andra delen av uppgiften går dels ut på att undersöka hur elever i gymnasiet, årskurs två tolkar och utför geometri men även hur lärare utför och förhåller sig till geometriundervisningen. Uppgiften som eleverna löste var i grupper av tre, där jag spelade in elevernas samtal för att sedan kunna analysera dem. Jag kommer med hjälp av Van Hielenivåer försöka kategorisera var deras förståelse ligger samtidigt som jag isolerar vilken nivå som det möjligtvis finns kunskapsbrister på och föreslå vad som kan göras för att åtgärda dessa brister. Det framkom tydligt hur elevernas förmåga att ta fram tidigare inhämtad kunskap i en situation utan instruktioner var svårt för dem, där brist i deras analytiska förmåga var mest framträdande

CYSTIC-FIBROSIS PATIENTS FROM THE BLACK-SEA REGION - THE 1677DELTA MUTATION

A 2 bp deletion in exon 10 of the CFTR gene, 1677delTA, which is very rare among CF chromosomes worldwide, was found to be a relatively common cause of cystic fibrosis in countries located in the region of the Black Sea. The frequency of the mutation was compared among cystic fibrosis patients from several populations, namely Bulgarians, Turks, Greek-Cypriots, Georgians, and Russians. The deletion is most common among Georgian CF patients and gradually declines in frequency in neighbouring populations. It is invariably related to a common polymorphic haplotype which is rare among normal chromosomes in Bulgaria but was found to be common in Turkey. The geographic gradient in the frequency of the mutation, along with findings on polymorphic haplotype distribution, suggest that the mutation is relatively young in evolutionary terms and spread as the result of west and south-bound migrations originating from Georgia. The 1677delTA mutation is related to a severe clinical phenotype with a high early mortality rate among homozygotes and possibly to an increased risk of meconium ileus. (C) 1994 Wiley-Liss, Inc