1,961 research outputs found
Short communication: Study on epilithic diatoms in the Kozluk Creek (Arapgir-Malatya, Turkey)
Being the most important members of phytoplankton and phytobenthos, both of which are the primary producers of surface water resources, algae play a very important role in the biological productivity of waters with their oxygen production through photosynthesis and they synthesize the organic materials. Furthermore, with their high levels of protein, algae are used as human and animal food as well as being used in the production of organic fertilizers and organic vitamins. Another reason for algae currently being among the most researched organisms is their easy and inexpensive productions in culture media. With the recognition of the importance of algae in standing waters and streams, the number of studies conducted on these organisms has rapidly increased. In Turkey, the number of studies on algae in streamsis quite high [(Altuner and Gurbuz (1989), Altuner and Gurbuz (1991) Yıldız (1991) , Yildiz and Ozkiran (1994), Ertan and Morkoyunlu (1998), Sahin (1998), Cetin and Yavuz (2001), Solak et al. (2012), Sivaci and Dere (2007), Mumcu et al. (2009), Pala and Caglar (2008)]
In vivo MRI with Concurrent Excitation and Acquisition using Automated Active Analog Cancellation
Magnetic resonance imaging (MRI) provides excellent cross-sectional images of the soft tissues in patients. Unfortunately, MRI is intrinsically slow, it exposes patients to severe acoustic noise levels, and is limited in the visualization of certain tissues such as bone. These limitations are partly caused by the timing structure of the MRI exam which first generates the MR signal by a strong radio-frequency excitation and later acquires the weak MRI signal. Concurrent excitation and acquisition (CEA) can overcome these limitations, but is extremely challenging due to the huge intensity difference between transmit and receive signal (up to 100 dB). To suppress the strong transmit signals during signal reception, a fully automated analog cancellation unit was designed. On a 3 Tesla clinical MRI system we achieved an on-resonance analog isolation of 90 dB between the transmit and receive path, so that CEA images of the head and the extremities could be acquired with an acquisition efficiency of higher than 90% at sound pressure levels close to background noise. CEA with analog cancellation might provide new opportunities for MRI in tissues with very short T2 relaxation times, and it offers a silent and time-efficient MRI acquisition
Short communication: Study on epilithic diatoms in the Balikli Tohma Creek (Darende/Malatya in Turkey)
Water, being the source of life, contains many life forms. The number and diversity of algae, which constitutes the first link of the food chain, affect all living things within the aquatic environment including fish. With its streams and lakes that cover an area of approximately 10000 km2, Turkey has very important internal water resources. About 135 of the wetlands within the borders of Turkey have international importance. Twelve of those have been declared as Ramsar areas (Anonymous, 2009).The structure of diatom communities has been directly linked to the physical and chemical state of water. Therefore, diatoms are used in water quality calculations and comparisons among rivers that have different morpho¬dynamics (Allan, 1995). The Water Framework Directive has established diatom communities as an indicator for stream systems besides the physico¬chemical parameters (APHA, 1985). The inert algal species that typically cover stones and hard rocks, and exist in mucilaginous and filiform masses constitute the epilithic flora. There have been many studies in Turkey on epilithic and epiphytic diatoms. Some of those studies have been on rivers whereas some have been on creeks that periodically dry up or freeze (Altuner and Gurbuz, 1988; Dere and Sivaci, 1995; Yildiz and Atici, 1996; Pala and Caglar, 2006; Pala and Caglar, 2008; Cicek and Ertan, 2015)
Role of a Novel Heparanase Inhibitor on the Balance between Apoptosis and Autophagy in U87 Human Glioblastoma Cells
Background: Heparanase (HPSE) is an endo-& beta;-glucuronidase that cleaves heparan sulfate side chains, leading to the disassembly of the extracellular matrix, facilitating cell invasion and metastasis dissemination. In this research, we investigated the role of a new HPSE inhibitor, RDS 3337, in the regulation of the autophagic process and the balance between apoptosis and autophagy in U87 glioblastoma cells. Methods: After treatment with RDS 3337, cell lysates were analyzed for autophagy and apoptosis-related proteins by Western blot. Results: We observed, firstly, that LC3II expression increased in U87 cells incubated with RDS 3337, together with a significant increase of p62/SQSTM1 levels, indicating that RDS 3337 could act through the inhibition of autophagic-lysosomal flux of LC3-II, thereby leading to accumulation of lipidated LC3-II form. Conversely, the suppression of autophagic flux could activate apoptosis mechanisms, as revealed by the activation of caspase 3, the increased level of cleaved Parp1, and DNA fragmentation. Conclusions: These findings support the notion that HPSE promotes autophagy, providing evidence that RDS 3337 blocks autophagic flux. It indicates a role for HPSE inhibitors in the balance between apoptosis and autophagy in U87 human glioblastoma cells, suggesting a potential role for this new class of compounds in the control of tumor growth progression
LOFAR discovery of a double radio halo system in Abell 1758 and radio/X-ray study of the cluster pair
Radio halos and radio relics are diffuse synchrotron sources that extend over Mpc-scales and are found in a number of merger galaxy clusters. They are believed to form as a consequence of the energy that is dissipated by turbulence and shocks in the intra-cluster medium (ICM). However, the precise physical processes that generate these steep synchrotron spectrum sources are still poorly constrained. We present a new LOFAR observation of the double galaxy cluster Abell 1758. This system is composed of A1758N, a massive cluster hosting a known giant radio halo, and A1758S, which is a less massive cluster whose diffuse radio emission is confirmed here for the first time. Our observations have revealed a radio halo and a candidate radio relic in A1758S, and a suggestion of emission along the bridge connecting the two systems which deserves confirmation. We combined the LOFAR data with archival VLA and GMRT observations to constrain the spectral properties of the diffuse emission. We also analyzed a deep archival Chandra observation and used this to provide evidence that A1758N and A1758S are in a pre-merger phase. The ICM temperature across the bridge that connects the two systems shows a jump which might indicate the presence of a transversal shock generated in the initial stage of the merger
Mechanism of action of probiotics
The modern diet doesn't provide the required amount of beneficial bacteria. Maintenance of a proper microbial ecology in the host is the main criteria to be met for a healthy growth. Probiotics are one such alternative that are supplemented to the host where by and large species of Lactobacillus, Bifidobacterium and Saccharomyces are considered as main probiotics. The field of probiotics has made stupendous strides though there is no major break through in the identification of their mechanism of action. They exert their activity primarily by strengthening the intestinal barrier and immunomodulation. The main objective of the study was to provide a deep insight into the effect of probiotics against the diseases, their applications and proposed mechanism of action
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All-optical detection of neuronal membrane depolarization in live cells using colloidal quantum dots
Luminescent semiconductor quantum dots (QDs) have recently been suggested as novel probes for imaging and sensing cell membrane voltages. However, a key bottleneck for their development is a lack of techniques to assess QD responses to voltages generated in the aqueous electrolytic environments typical of biological systems. Even more generally, there have been relatively few efforts to assess the response of QDs to voltage changes in live cells. Here, we develop a platform for monitoring the photoluminescence (PL) response of QDs under AC and DC voltage changes within aqueous ionic environments. We evaluate both traditional CdSe/CdS and more biologically compatible InP/ZnS QDs at a range of ion concentrations to establish their PL/voltage characteristics on chip. Wide-field, few-particle PL measurements with neuronal cells show the QDs can be used to track local voltage changes with greater sensitivity (ΔPL up to twice as large) than state-of-the-art calcium imaging dyes, making them particularly appealing for tracking sub-threshold events. Additional physiological observation studies showed that whilst CdSe/CdS dots have greater PL responses on membrane depolarization, their lower cytotoxicity makes InP/ZnS far more suitable for voltage sensing in living systems. Our results provide a methodology for the rational development of QD voltage sensors and highlight their potential for imaging changes in cell membrane voltage.EPSRC Doctoral Training Award (EP/L016087/1
Development and Validation of the Parent-Initiated Motivational Climate in Individual Sport Competition Questionnaire
This paper presents a series of studies that progresses the development and validation of the Parent-Initiated Motivational Climate in Individual Sport Competition Questionnaire (MCISCQ-Parent). Study 1 examined the face and content validity of an initial pool of 26 items based on the principles of achievement goal theory and prior research. In Study 2, data from an adolescent sample of individual sport athletes was subjected to an exploratory factor analysis (EFA) of items pertaining to the perceived task and ego involving characteristics of fathers and mothers in the competition setting. Study 3 tested the factor structure of the MCISCQ-Parent through confirmatory factor analysis (CFA) in a further youth athlete sample. Following appropriate CFA-related modifications, good goodness of fit indices emerged for the father- (three factor-model) and mother-related (two factor-model) dimensions of motivational climate. In Study 4, a further CFA was conducted and provided additional evidence for the revised factor structure of the MCISCQ-Parent, convergent and discriminant validity, and internal consistency. Finally, Study 5 provided support for the concurrent validity of the MCISCQ-Parent by demonstrating significant relationships between MCISCQ-Parent subscales and task and ego orientation, athlete engagement, and perceived social support. In sum, we present the MCISCQ-Parent as a measure with promising psychometric properties, and specifically to those applied researchers interested in assessing the quality of motivation-related parental involvement perceived by young athletes in the competition setting
BAT AGN Spectroscopic Survey XXVII: Scattered X-Ray Radiation in Obscured Active Galactic Nuclei
Accreting supermassive black holes (SMBHs), also known as active galactic
nuclei (AGN), are generally surrounded by large amounts of gas and dust. This
surrounding material reprocesses the primary X-ray emission produced close to
the SMBH and gives rise to several components in the broadband X-ray spectra of
AGN, including a power-law possibly associated with Thomson-scattered
radiation. In this work, we study the properties of this scattered component
for a sample of 386 hard-X-ray-selected, nearby () obscured AGN
from the 70-month Swift/BAT catalog. We investigate how the fraction of
Thomson-scattered radiation correlates with different physical properties of
AGN, such as line-of-sight column density, X-ray luminosity, black hole mass,
and Eddington ratio. We find a significant negative correlation between the
scattering fraction and the column density. Based on a large number of spectral
simulations, we exclude the possibility that this anti-correlation is due to
degeneracies between the parameters. The negative correlation also persists
when considering different ranges of luminosity, black hole mass, and Eddington
ratio. We discuss how this correlation might be either due to the angle
dependence of the Thomson cross-section or to more obscured sources having a
higher covering factor of the torus. We also find a positive correlation
between the scattering fraction and the ratio of [OIII] 5007 to X-ray
luminosity. This result is consistent with previous studies and suggests that
the Thomson-scattered component is associated with the narrow-line region.Comment: Accepted for publication in MNRAS, 18 pages, 9 figures, 2 tables, 1
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