83 research outputs found
Relationships between the physicochemical parameters and zooplankton in Eğirdir Lake (Turkey)
The zooplankton community structure in Eğirdir Lake (Isparta-Turkey) was studied monthly throughout an annual cycle (January 2010-December 2010). The zooplankton community was represented by three main groups: Rotifera, Cladocera and Copepoda, respectively comprised 89.62%, 7.78% and 2.60% of the total zooplankton abundance. Eğirdir Lake was dominated by the rotifera Polyarthra dolichoptera in September and October, that succeeded by cladocera Bosmina longirostris species during December. Canonical correspondance analysis (CCA) was used to relate species distribution to environmental factors. The variation in the species data was significantly (p<0.05) related to a set of environmental variables (conductivity, carbonate, pH, ammonium, organic substances, dissolved oxygen, saturation of dissolved oxygen, chloride and temperature). According to the CCA result, variables were able to explain 81.9% of the total variation suggesting a significant result. The rotifer, Asplanchna priodonta, and the crustaceans, B. longirostris and Nauplius larvae seemed to be affected by environmental gradients
The effects of physicochemical parameters on fish distribution in Eğirdir Lake, Turkey
The present study was conducted based on the fish species and physicochemical parameters of Eğirdir Lake. Sampling was carried out monthly from January through December 2010 between 9 am and 11 am. The parameters measured were water temperature, depth, secchi disk depth, turbidity, dissolved oxygen, saturation of dissolved oxygen, pH, conductivity, chloride, hardness, calcium, magnesium, bicarbonate, carbonate, nitrate, nitrite, ammonium, sulphate, phosphate, silica, organic substance, acid power (SBV) and chlorophyll-a. Monthly sampling was performed at four stations at different depths. Water temperature ranged from 6.9±0.5 °C in February to 26.8±0.4 °C in August. Minimum secchi disk depth recorded was 0.5 m while the maximum was 2.4 m. Dissolved oxygen ranged from 4.2±0.2 to 12.6±0.6 mgL^-1. The pH values ranged from 8.4 to 9.6. In this study, 15 fish species, belonging to eight families were identified. Among the 15 fish species recorded, Cyprinidae was the dominant family followed by Percidae (3%). According to detrended correspondence analysis (DCA), variables were able to explain 90% of total variation suggesting a significant result. The results showed that water temperature, dissolved oxygen and saturation of dissolved oxygen were the most important physicochemical parameters affecting fish distribution. Other physicochemical parameters of this lake did not show any significant statistical differences in determining fish distribution
Comparison of sirolimus and colchicine treatment on the development of peritoneal fibrozis in rats having peritoneal dialysis
Background: Continuous ambulatory peritoneal dialysis is a successful treatment modality for patients with end-stage renal disease. Peritoneal fibrosis (PF) is the most critical complication of long-term peritoneal di- alysis (PD). Aims: In our study, we aimed to compare the effects of colchicine and sirolimus on PF induced by hypertonic peritoneal dialysis solutions in rats. Study Design: Animal experiment. Methods: Twenty-four rats were randomly divided into three groups. The control group received an intraperitoneal injection (ip) of saline. The sirolimus group received the PD solution, plus 1.0 mg/kg/day Rapamune®. The colchicine group received the PD solution ip plus 1.0 mg/kg/day of colchicine. Blood sam- ples were taken to measure the serum levels of VEGF, TGF-&#946;, and TNF-&#945;. Peritoneal tissue samples were taken for histopathological evaluation. Results: TGF-&#946; and TNF-&#945; values in the sirolimus group were found to be statistically significantly lower than in the control and colchicine groups, but the differences between the control and colchicine groups were not statistically significant. No statistically significant differences were found between the groups regarding the VEGF values. Vascular neogenesis and peritoneal thickness were compared; the values in the sirolimus group were statistically reduced compared to the values in the control group. Mild fibrosis developed in 75% of all animals in the sirolimus group; there was no moderate or severe fibrosis observed. Fibrosis developed to varying degrees in 100% of the animals in the control and colchicine groups. Conclusion: The present study demonstrates that sirolimus might be beneficial for preventing or delaying the progression of PF and neoangiogenesis. These alterations in the peritoneal membrane may be connected with reduced TNF-&#945; and TGF-&#946; levels
Biomedical image time series registration with particle filtering (Parçacık süzgeci ile biyomedikal görüntü zaman serisi çakıştırma)
We propose a family of methods for biomedical image time series registration based on Particle filtering. The first method applies an intensity-based information-theoretic approach to calculate importance weights. An effective second group of methods use landmark-based approaches for the same purpose by automatically detecting intensity maxima or SIFT interest points from image time series. A brute-force search for the best alignment usually produces good results with proper cost functions, but becomes computationally expensive if the whole search space is explored. Hill climbing optimizations seek local optima. Particle filtering avoids local solutions by introducing randomness and sequentially updating the posterior distribution representing probable solutions. Thus, it can be more robust for the registration of image time series. We show promising preliminary results on dendrite image time series
Fabrication of quantum emitters in aluminium nitride by Al-ion implantation and thermal annealing
Single-photon emitters (SPEs) within wide-bandgap materials represent an
appealing platform for the development of single-photon sources operating at
room temperatures. Group III- nitrides have previously been shown to host
efficient SPEs which are attributed to deep energy levels within the large
bandgap of the material, in a way that is similar to extensively investigated
colour centres in diamond. Anti-bunched emission from defect centres within
gallium nitride (GaN) and aluminium nitride (AlN) have been recently
demonstrated. While such emitters are particularly interesting due to the
compatibility of III-nitrides with cleanroom processes, the nature of such
defects and the optimal conditions for forming them are not fully understood.
Here, we investigate Al implantation on a commercial AlN epilayer through
subsequent steps of thermal annealing and confocal microscopy measurements. We
observe a fluence-dependent increase in the density of the emitters, resulting
in creation of ensembles at the maximum implantation fluence. Annealing at 600
{\deg}C results in the optimal yield in SPEs formation at the maximum fluence,
while a significant reduction in SPE density is observed at lower fluences.
These findings suggest that the mechanism of vacancy formation plays a key role
in the creation of the emitters, and open new perspectives in the defect
engineering of SPEs in solid state.Comment: 11 pages, 7 figure
Evanescent-field assisted photon collection from quantum emitters under a solid immersion lens
Solid-state quantum light sources are being intensively investigated for applications in quantum technology. A key challenge is to extract light from host materials with high refractive index, where efficiency is limited by refraction and total internal reflection. Here we show that an index-matched solid immersion lens can, if placed sufficiently close to the semiconductor, extract light coupled through the evanescent field at the surface. Using both numerical simulations and experiments, we investigate how changing the thickness of the spacer between the semiconductor and lens impacts the collection efficiency (CE). Using automatic selection and measurement of 100 s of individually addressable colour centres in several aluminium nitride samples we demonstrate spacer-thickness dependent photon CE enhancement, with a mean enhancement factor of 4.2 and a highest measured photon detection rate of 743±4kcps
The Offshoring of Production Activities in European Manufacturing
We investigate production offshoring – the relocation of production activities to locations abroad – of European firms. The analysis employs data from the European Manufacturing Survey (EMS).
Offshoring activity is declining across most countries, sectors, and firm sizes between the periods 2004/06 and 2007/09. Regression analysis reveals that this decline is also significant after controlling for firm characteristics. Long-term data for Germany indicate that this decrease is part of a longer trend which already started in 2003.
Despite the general decrease in offshoring, far-shoring to Asia in general and to China in particular has increased. In contrast, near-shoring to EU member states in Middle and Eastern Europe (EU-12) became less attractive. The EU-12, however, is still the most important target region for offshoring activities of European firms.
The dominant motive for offshoring is the wish to reduce labour costs. Expected labour cost reductions explain offshoring to the EU-12, Asia and China in particular. Vicinity to customers and market expansion follow as a motive with a wide margin. However, in contrast to the EU-12, where the offshoring decision is solely dominated by potential labour cost savings, offshoring activities to Asia and China are also significantly related to market expansion motives
Post-Covid-19 Irritable Bowel Syndrome
Objectives The long-term consequences of COVID-19 infection on the gastrointestinal tract remain unclear. Here, we aimed to evaluate the prevalence of gastrointestinal symptoms and post-COVID-19 disorders of gut-brain interaction after hospitalisation for SARS-CoV-2 infection. Design GI-COVID-19 is a prospective, multicentre, controlled study. Patients with and without COVID-19 diagnosis were evaluated on hospital admission and after 1, 6 and 12 months post hospitalisation. Gastrointestinal symptoms, anxiety and depression were assessed using validated questionnaires. Results The study included 2183 hospitalised patients. The primary analysis included a total of 883 patients (614 patients with COVID-19 and 269 controls) due to the exclusion of patients with pre-existing gastrointestinal symptoms and/or surgery. At enrolment, gastrointestinal symptoms were more frequent among patients with COVID-19 than in the control group (59.3% vs 39.7%, p < 0.001). At the 12-month follow-up, constipation and hard stools were significantly more prevalent in controls than in patients with COVID-19 (16% vs 9.6%, p=0.019 and 17.7% vs 10.9%, p=0.011, respectively). Compared with controls, patients with COVID-19 reported higher rates of irritable bowel syndrome (IBS) according to Rome IV criteria: 0.5% versus 3.2%, p=0.045. Factors significantly associated with IBS diagnosis included history of allergies, chronic intake of proton pump inhibitors and presence of dyspnoea. At the 6-month follow-up, the rate of patients with COVID-19 fulfilling the criteria for depression was higher than among controls. Conclusion Compared with controls, hospitalised patients with COVID-19 had fewer problems of constipation and hard stools at 12 months after acute infection. Patients with COVID-19 had significantly higher rates of IBS than controls
Data Descriptor : A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins
Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.Peer reviewe
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