135 research outputs found
Modeling aerotaxis band formation in Azospirillum brasilense
Background
Bacterial chemotaxis, the ability of motile bacteria to navigate gradients of chemicals, plays key roles in the establishment of various plant-microbe associations, including those that benefit plant growth and crop productivity. The motile soil bacterium Azospirillum brasilense colonizes the rhizosphere and promotes the growth of diverse plants across a range of environments. Aerotaxis, or the ability to navigate oxygen gradients, is a widespread behavior in bacteria. It is one of the strongest behavioral responses in A. brasilense and it is essential for successful colonization of the root surface. Oxygen is one of the limiting nutrients in the rhizosphere where density and activity of organisms are greatest. The aerotaxis response of A. brasilense is also characterized by high precision with motile cells able to detect narrow regions in a gradient where the oxygen concentration is low enough to support their microaerobic lifestyle and metabolism.
Results
Here, we present a mathematical model for aerotaxis band formation that captures most critical features of aerotaxis in A. brasilense. Remarkably, this model recapitulates experimental observations of the formation of a stable aerotactic band within 2 minutes of exposure to the air gradient that were not captured in previous modeling efforts. Using experimentally determined parameters, the mathematical model reproduced an aerotactic band at a distance from the meniscus and with a width that matched the experimental observation.
Conclusion
Including experimentally determined parameter values allowed us to validate a mathematical model for aerotactic band formation in spatial gradients that recapitulates the spatiotemporal stability of the band and its position in the gradient as well as its overall width. This validated model also allowed us to capture the range of oxygen concentrations the bacteria prefer during aerotaxis, and to estimate the effect of parameter values (e.g. oxygen consumption rate), both of which are difficult to obtain in experiments
Zoledronic acid induces apoptosis via stimulating the expressions of ERN1, TLR2, and IRF5 genes in glioma cells
Glioblastoma multiforme (GBM) is the most common and aggressive brain tumor that affects older people. Although the current therapeutic approaches for GBM include surgical resection, radiotherapy, and chemotherapeutic agent temozolomide, the median survival of patients is 14.6 months because of its aggressiveness. Zoledronic acid (ZA) is a nitrogen-containing bisphosphonate that exhibited anticancer activity in different cancers. The purpose of this study was to assess the potential effect of ZA in distinct signal transduction pathways in U87-MG cells. In this study, experiments performed on U87-MG cell line (Human glioblastoma-astrocytoma, epithelial-like cell line) which is an in vitro model of human glioblastoma cells to examine the cytotoxic and apoptotic effects of ZA. IC50 dose of ZA, 25 μM, applied on U87-MG cells during 72 h. ApoDIRECT In Situ DNA Fragmentation Assay was used to investigate apoptosis of U87MG cells. The quantitative reverse transcription polymerase chain reaction (qRT-PCR) (LightCycler480 System) was carried out for 48 gene expression like NF-κB, Toll-like receptors, cytokines, and inteferons. Our results indicated that ZA (IC50 dose) increased apoptosis 1.27-fold in U87MG cells according to control cells. According to qRT-PCR data, expression levels of the endoplasmic reticulum-nuclei-1 (ERN1), Toll-like receptor 2 (TLR2), and human IFN regulatory factor 5 (IRF5) tumor suppressor genes elevated 2.05-, 2.08-, and 2.3-fold by ZA, respectively, in U87MG cells. Our recent results indicated that ZA have a key role in GBM progression and might be considered as a potential agent in glioma treatment. © 2015, International Society of Oncology and BioMarkers (ISOBM)
Faster linearizability checking via -compositionality
Linearizability is a well-established consistency and correctness criterion
for concurrent data types. An important feature of linearizability is Herlihy
and Wing's locality principle, which says that a concurrent system is
linearizable if and only if all of its constituent parts (so-called objects)
are linearizable. This paper presents -compositionality, which generalizes
the idea behind the locality principle to operations on the same concurrent
data type. We implement -compositionality in a novel linearizability
checker. Our experiments with over nine implementations of concurrent sets,
including Intel's TBB library, show that our linearizability checker is one
order of magnitude faster and/or more space efficient than the state-of-the-art
algorithm.Comment: 15 pages, 2 figure
On determining spectral parameters, tracking jitter, and GPS positioning improvement by scintillation mitigation
A method of determining spectral parameters p (slope of the phase PSD) and T (phase PSD at 1 Hz) and hence tracking error variance in a GPS receiver PLL from just amplitude and phase scintillation indices and an estimated value of the Fresnel frequency has been previously presented. Here this method is validated using 50 Hz GPS phase and amplitude data from high latitude receivers in northern Norway and Svalbard. This has been done both using (1) a Fresnel frequency estimated using the amplitude PSD (in order to check the accuracy of the method) and (2) a constant assumed value of Fresnel frequency for the data set, convenient for the situation when contemporaneous phase PSDs are not available. Both of the spectral parameters ( p, T ) calculated using this method are in quite good agreement with those obtained by direct measurements of the phase spectrum as are tracking jitter variances determined for GPS receiver PLLs using these values. For the Svalbard data set, a significant difference in the scintillation level observed on the paths from different satellites received simultaneously was noted. Then, it is shown that the accuracy of relative GPS positioning can be improved by use of the tracking jitter variance in weighting the measurements from each satellite used in the positioning estimation. This has significant advantages for scintillation mitigation, particularly since the method can be accomplished utilizing only time domain measurements thus obviating the need for the phase PSDs in order to extract the spectral parameters required for tracking jitter determination
A focusing study on radioprotective and antioxidant effects of Annona muricata leaf extract in the circulation and liver tissue: Clinical and experimental studies
Objectives: This study investigates the effect of Annona muricata (AM) leaf extract against irradiation-induced damage by the evaluation of hepatic tissue and the levels of oxidative and inflammatory stress in the circulation. Methods: An experimental study with 37 female Wistar albino rats randomized into four groups (controls and three intervention groups) was performed. The first interventional group (group 2) received 300 mg/kg of AM leaf extract by oral gavage once a day for 9 days, group 3 received a single dose of whole-body radiation (8.3 Gy) after a 9-day oral gavage treatment with saline, and the last group received the same irradiation of 8.3 Gy after being treated with 300 mg/kg of AM leaf extract by oral gavage once a day for 9 days. Results: Radiation was found to elevate reactive oxygen species parameters, and AM administration before irradiation was found to decrease total oxidant status (TOS), increase caspase 9, and improve hepatic damage when compared with the group that received only irradiation. Conclusion: The damage caused by irradiation may be ameliorated by the use of the AM extract, which appears to be effective in preventing oxidative stress and inflammatory activity. © 2022 Ozlem Elmas et al.Dunarea de Jos” University of GalatiUniversitatea 'Dunărea de Jos' Galați, UDJG, (RF 3621/2021)Funding text 1: Author contributions: O.E., H.H.K.S., H.O.T.: conceptualization and methodologyM.A., W.E., G.A.: validationG.A. and H.M.H.Z.: formal analysisO.E., H.H.K.S., B.G., H.O.T.: writing and reviewO.E., H.H.K.S., B.G., A.E., M.A., W.E.: investigationA.E.: funding acquisition through APC by “Dunarea de Jos” University of Galati, Romania through the grant no. RF 3621/2021.Funding text 2: Funding information: The work of Antoaneta ENE and the APC were supported by Dunarea de Jos University of Galati, Romania through the grant no. RF 3621/2021
Fundamental social motives measured across forty-two cultures in two waves
How does psychology vary across human societies? The fundamental social motives framework adopts an evolutionary approach to capture the broad range of human social goals within a taxonomy of ancestrally recurring threats and opportunities. These motives—self-protection, disease avoidance, affiliation, status, mate acquisition, mate retention, and kin care—are high in fitness relevance and everyday salience, yet understudied cross-culturally. Here, we gathered data on these motives in 41 countries (N=15,885) in two cross-sectional waves, including 19 countries (N=11,095) for which data were gathered in both waves. Wave 1 was collected from 2016 through mid-2019 (32 countries, N=9353; 3537 male, 5574 female; Mage=24.58, SD=8.07). Wave 2 was collected from May through October 2020, during the COVID-19 pandemic (N=6532; 2194 male, 4165 female; Mage=28.82, SD=11.49). These data can be used to assess differences and similarities in people’s fundamental social motives both across and within cultures, at different time points, and in relation to other commonly studied cultural indicators and outcomes
Effect of hesperidin treatment on α-Klotho/FGF-23 pathway in rats with experimentally-induced diabetes
Objective Non-alcoholic fatty liver disease, steatohepatitis and nephropathy are considered among the mostimportant complications of diabetes mellitus (DM), which recently increased due to increased frequency of DMand the prolonged life span of diabetic patients The aim of the present study was to reveal the possible effect ofhesperidin (HP) on alpha-klotho (α-KL)/fibroblast growth factor-23 (FGF-23) pathway in rats with diabetesinduced by streptozotocin (STZ).Materials and methods Thirty six male Sprague-Dawley rats were randomly divided into three groups. Therats of the control, diabetes, and treatment groups were fed with standard feed and water throughout the 2-weekstudy. In order to induce diabetes mellitus in rats, those in the diabetes group were administered a single dose of50 mg/kg STZ. For the DM + HP group, a single dose of 50 mg/kg STZ, when diabetes was induced, hesperidinwas administered orally at a dose of 100 mg/kg by gavage.Results Theα-KL levels of our study groups, both the liver and kidneyα-KL levels and serumα-KL of the STZ-induced diabetic group were statistically significantly lower than the control group (respectively, p < 0.05,p < 0.001, p < 0.05). It was observed that hesperidin administration statistically significantly increasedα-KLlevels in serum, liver and renal tissue (p < 0.001). Liver, kidney and serum FGF-23 levels of the diabetic groupincreased significantly in comparison to the control group (respectively, p < 0.05, p < 0.01, p < 0.001). FGF-23 levels that increased in kidney tissue and serum samples of the diabetic group decreased statistically sig-nificantly with hesperidin administration (respectively, p < 0.01, p < 0.001).Conclusion Theα-KL/FGF-23 pathway is a promising bio-indicator in various cases of systemic toxicity andpathology. In addition, the strong positive effects of hesperidin administration on diabetic toxicity in the liverand kidneys suggest that it may be included in the alternative treatment methods in the future.This work was supported by Coordinator of Scientific Research Projects ( 2017.M83.02.01 ) at University of Artvin Coruh
Clinical comprehensive and experimental assessment of the radioprotective effect of Annona muricata leaf extract to prevent cellular damage in the ileum tissue
We report the radioprotective attitude of Annona muricata (AM) leaf extract as antioxidant material to prevent cellular damage in the ileum tissue. The protective effects of an ethyl acetate extract of AM leaves are comprehensively investigated against radiation-induced ileal damage in numerous rats. Thirty-two adult female rats were separated into 4 groups (3 intervention groups and 1 control) as follows: controls received 0.01 mL/kg distilled water, the AM group received 300 mg/kg AM leaf extract, the ionizing radiation (IR) group received a single dose of whole body radiation (8.3 Gy) after 0.01 mL/kg saline treatment, and the AM + IR group received 300 mg/kg AM leaf extract treatment and were subjected to whole body radiation (8.3 Gy) 1 h after the last gavage. All treatments are administered by oral gavage once a day for 9 days. At the end of the experiment, biochemical total oxidant status (TOS, interleukin-6, and caspase) and histological examinations are performed on blood samples as well as ileum tissue. TOS levels are found to be significantly high in rats, which received irradiation, and those in the AM group when compared to controls. These findings suggest that AM has radioprotective effects on ileum tissue, likely because of its antioxidative properties. The findings of this research may contribute to the minimizing of major side effects induced by excessive radiation exposure in patients undergoing radiotherapy and may serve as a significant impetus for further assessments. However, future studies are highly recommended to confirm safety and to determine extraction technique and dosage before human use can be considered. © 2022 Ozlem Elmas et al.Dunarea de Jos” University of Galati, (RF 3621/2021)Universitatea 'Dunărea de Jos' Galați, UDJGFunding text 1: Funding information: The work of Antoaneta ENE and the APC were supported by Dunarea de Jos University of Galati, Romania through the grant no. RF 3621/2021.Funding text 2: Author contributions: O.E., H.H.K.S., and H.O.T.: – conceptualization and methodologyE.K., B.G., G.A., and R.U.E.: validationG.A. and H.M.H.Z.: formal analysisO.E., H.H.K.S., E.K., B.G., and H.O.T.: writing and reviewO.E., H.H.K.S., E.K., B.G., and A.E.: investigationA.E.: funding acquisition through APC by “Dunarea de Jos” University of Galati, Romania through the grant no. RF 3621/2021
Five-frequency Galileo long-baseline ambiguity resolution with multipath mitigation
© 2018, The Author(s). For long-baseline over several hundreds of kilometers, the ionospheric delays that cannot be fully removed by differencing observations between receivers hampers rapid ambiguity resolution. Compared with forming ionospheric-free linear combination using dual- or triple-frequency observations, estimating ionospheric delays using uncombined observations keeps all the information of the observations and allows extension of the strategy to any number of frequencies. As the number of frequencies has increased for the various GNSSs, it is possible to study long-baseline ambiguity resolution performance using up to five frequencies with uncombined observations. We make use of real Galileo observations on five frequencies with a sampling interval of 1 s. Two long baselines continuously receiving signals from six Galileo satellites during corresponding test time intervals were processed to study the formal and empirical ambiguity success rates in case of full ambiguity resolution (FAR). The multipath effects are mitigated using the measuremen ts of another day when the constellation repeats. Compared to the results using multipath-uncorrected Galileo observations, it is found that the multipath mitigation plays an important role in improving the empirical ambiguity success rates. A high number of frequencies are also found to be helpful to achieve high ambiguity success rate within a short time. Using multipath-uncorrected observations on two, three, four and five frequencies, the mean empirical success rates are found to be about 73, 88, 91, and 95% at 10 s, respectively, while the values are increased to higher than 86, 95, 98, and 99% after mitigating the multipath effects
An example of secondary fault activity along the North Anatolian Fault on the NE Marmara Sea Shelf, NW Turkey
Seismic data on the NE Marmara Sea Shelf indicate that a NNE-SSW-oriented buried basin and ridge system exist on the sub-marine extension of the Paleozoic Rocks delimited by the northern segment of the North Anatolian Fault (NS-NAF), while seismic and multi-beam bathymetric data imply that four NW-SE-oriented strike-slip faults also exist on the shelf area. Seismic data indicate that NW-SE-oriented strike-slip faults are the youngest structures that dissect the basin-ridge system. One of the NW-SE-oriented faults (F1) is aligned with a rupture of the North Anatolian Fault (NAF) cutting the northern slope of the Cinarcik Basin. This observation indicates that these faults have similar characteristics with the NS-NAF along the Marmara Sea. Therefore, they may have a secondary relation to the NAF since the principle deformation zone of the NAF follows the Marmara Trough in that region. The seismic energy recorded on these secondary faults is much less than that on the NAF in the Marmara Sea. These faults may, however, produce a large earthquake in the long term
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