140,059 research outputs found
Spatially-localized time dependent solutions including turbulence and their interactions in 2D Kolmogorov flow
No full textIn 2D Kolmogorov flow in small aspect ratio domains, spatially-localized solutions such as kink, traveling or time-dependent kink-antikink pars coexist. However, the conservation of the flow rate in the y direction strongly restrict combination of localized solutions and their positioning. We find that by adding a homogeneous flow U y their positioning is controlled and each of localized solutions including a spatially-localized chaos is isolated. Numerical results suggest that these isolated solutions can be elements constructing a whole flow
MicroRNAs in spent blastocyst culture medium are derived from trophectoderm cells and can be explored for human embryo reproductive competence assessment
No full textObjective: To assess whether extracellular microRNAs (miRNAs) can be accurately profiled from spent blastocyst culture media (SBM) and used as embryonic biomarkers.
Design: Prospective cohort study.
Setting: Private and academic in vitro fertilization centers.
Patient(s): Inner cell mass-free trophectoderm (TE) samples and their relative SBM from five good-quality human blastocysts.
Intervention(s): Protocol for miRNA purification and analysis based on quantitative polymerase chain reaction set and validated on human embryonic stem cells (hESCs) and on SBM with and without biological variability.
Main outcomes measure(s): Analysis of miRNAs in culture media in relation with TE cells and comparison of miRNA profiles between implanted and unimplanted euploid blastocysts.
Result(s): Culture media from embryos in the cleavage, morula, and blastocyst stages were collected to investigate the presence of miRNAs. The SBM were prospectively collected from euploid implanted (n = 25) and unimplanted blastocysts (n = 28) for comparison. We hypothesized that human embryos secrete miRNAs in culture media that can be used as biomarkers. The comparative analysis of TE and SBM samples revealed that 96.6% (57 of 59; 95 CI, 88.3-99.6) of the miRNAs detected in the SBM were expressed from TE cells, suggesting a TE origin. The culture media collected from cleavage and morula stage embryos showed a pattern similar to blanks, suggesting that miRNAs profiling from spent culture media applies only for blastocysts. MicroRNAs analysis of SBM from euploid implanted and unimplanted blastocysts highlighted two miRNAs (miR-20a, miR-30c) that showed increased concentrations in the former and were predicted in silico to be involved in 23 implantation-related pathways.
Conclusion(s): MicroRNAs secreted from human blastocysts in culture media can be profiled with high reproducibility, and this approach can be further explored for noninvasive embryo selection
Reply: Rapid changes in practice make analysis of historical databases irrelevant for contemporary counselling
No full textCharacteristics of overlap region in high-Reynolds number turbulent channel flow
No full textDirect numerical simulation of the fully developed turbulent channel flows have been carried out at the Reynolds number based on the friction velocity and the channel half width, 2000, 4000 and 8000. A hybrid 10th order accurate finite difference scheme in the stream and spanwise directions, and a second-order scheme in the wall-normal direction is adapted as the spatial discretization method. We observed the plateau profiles in the indicator function corresponded to the von Karman constant. Furthermore, second peak of streamwise pre-multiplied spectra were appeared in the same wall normal height, 300 < y+ < 600, in case of Re = 4000. Nevertheless, the effects of the lager than the channel half height scale on the streamwise turbulent intensity are fixed contributions without dependence on Reynolds number. These results suggested that the new streamwise vortexes are formed between buffer layer and outer layer with increasing of Reynolds number
Fly ash radiological characterization from thermal power plants in Iraq
No full textThe present study aims to measure the activity concentrations of radionuclides 238U, 232Th, 40K, 137Cs in samples of fly ashes collected from two thermal power plant in Iraq, by gamma spectroscopy using a NaI (Tl) detector. The radiological hazard related to these activities is also assessed through several worldwide commonly used indexes established by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The results are statistically presented, discussed and compared with literature and with worldwide reference averages: no significant radiation hazard comes from the analyzed fly ashes, although ~ 25% of the samples exceed the activity concentration limits
Comprehensive characterization of the human blastocyst's miRNome from the Inner Cell Mass, the Trophectoderm and their related IVF spent culture media
No full textStudy question: Can we consistently profile and characterize miRNAs from blastocoel cavity?
Summary answer: MicroRNAs can be consistently profiled in human blastocoel cavity and the population of miRNAs detected within the blastocoel is mostly heterogeneous with respect to the cellular counterparts of the blastocyst, with some miRNAs significantly up-regulated or preferentially expressed in the former with respect to human ICM and TE.
What is known already: Only proteomic and metabolomic analyses have been published up to date characterizing human blastocoel, but no data have been ever reported profi ling miRNAs within the inner cavity of a blastocyst. There are evidences of miRNAs secretion by donor cells in order to exert a gene regulatory effect upon recipient ones, highly suggesting the possibility of a miRNAs-mediated autocrine communication within the blastocyst via the blastocoel fluid.
Study design, size, duration: Five good quality expanded human blastocysts underwent blastocoel collection according to a previously published method between November and December 2014. Blastocoel samples were screened for miRNA content and compared to a reference database previously built on human ICM and TE miRNA expression profiles.
Participants/materials, setting, methods: MiRNA expression was evaluated using TLDA Cards A (Applied Biosystems) containing primer sets for 381 human miRNA sequences. Ct values at a level 37 cycles and miRNAs expressed in <60% biological replicates were excluded from the analysis. The mean expression level of expressed miRNAs was used for normalization.
Main results and the role of chance: Pearson’s correlation of raw Ct values among blastocoel samples ranged between 0.69 and 0.78. It was instead comprised between 0.33 and 0.45 when comparing them to ICM, and between 0.29 and 0.39 to TE. Minimum and maximum number of miRNAs detected in the blastocoel were 50 and 51. Thirty-three were expressed in at least 60% of samples run. Twenty-one out of them were also common to ICM (63.6%), 24 to TE (72.7%), and 19 to both (57.5%). Normalized Ct hierarchical clustering, built on complete linkage and Euclidean distance, highlighted a sharp division between ICM, TE and blastocoel. The volcano plot built on the parametric test Limma and Benjamini-Hochberg correction showed 6 and 7 miRNAs up-regulated (p < 0.001) in blastocoel versus ICM and TE, respectively. One and 2 were instead respectively down-regulated (p < 0.001).
Limitations, reason for caution: Since miRNAs secretion is a dynamic process throughout blastocyst expansion and only fresh good quality expanded blastocysts were included, we need data on blastocoels from thawed, bad quality and/or blastocysts of different expansion grades. Prospective studies are also needed to investigate correlations between blastocoel miRNA profi ling and blastocyst implantation.
Wider implications of the findings: This is the first profiling of miRNAs from blastocoel. It can mirror important parameters such as blastocyst morphological quality, metabolic or degenerative processes, and reproductive competence. To this regard, we still lack methods to boost our predictive power upon blastocyst implantation potential beyond current limits, and blastocoel miRNA evaluation is an unexplored strategy in this scenario.
Study funding/competing interest(s): Funding by hospital/clinic(s) – G.EN.E.R.A. centres for reproductive medicine.
Trial registration number: None
Live birth and perinatal outcomes following stimulated and unstimulated IVF: Analysis of over two decades of a nationwide data
No full textSTUDY QUESTION Does ovarian stimulation affect perinatal outcomes of preterm birth (PTB) and low birth weight (LBW) following IVF treatment. SUMMARY ANSWER Despite no significant differences in the risks of PTB and LBW between stimulated and unstimulated IVF in the present study, the study cannot exclude the effect of ovarian stimulation on the perinatal outcomes following IVF. WHAT IS ALREADY KNOWN Pregnancies resulting from assisted reproductive treatments (ART) are associated with a higher risk of pregnancy complications compared to spontaneously conceived pregnancies attributed to the underlying infertility and the in vitro fertilization techniques. It is of interest to determine the effect size of ovarian stimulation use in achieving a live birth and whether ovarian stimulation that is routinely used in IVF, affects perinatal outcomes of birth weight and gestational age at delivery compared to unstimulated IVF. STUDY DESIGN, SIZE, DURATION Anonymous data were obtained from the Human Fertilisation and Embryology Authority (HFEA), the statutory regulator of ART in the UK. The HFEA has collected data prospectively on all ART performed in the UK since 1991. Data from 1991 to 2011 comprising a total of 591 003 fresh IVF ± ICSI cycles involving 584 835 stimulated IVF cycles and 6168 unstimulated IVF cycles were analyzed. PARTICIPANTS/MATERIALS, SETTING, METHODS Data on all women undergoing either stimulated or unstimulated fresh IVF ± ICSI cycles during the period from 1991 to 2011 were analyzed to compare live birth rates, singleton live birth rates, perinatal outcomes of PTB, early PTB (<32 weeks), LBW and very LBW (<1500 grams) among singleton live births. Adjusted logistic regression was performed for each perinatal outcome for confounding factors: female age, period of treatment, cause of infertility, number of previous IVF cycles and previous live birth. MAIN RESULTS AND THE ROLE OF CHANCE Analysis of the large nationwide data demonstrated 3.5 times (95% confidence interval (CI): 3.1-3.9) as many unstimulated IVF cycles being required to achieve one live birth compared to stimulated IVF and 2.9 times (95% CI: 2.6-3.2) as many unstimulated IVF cycles being required to achieve one singleton live birth compared to stimulated IVF. There was no significant difference in the unadjusted odds for PTB (odds ratio (OR) 1.27, 95% CI: 0.80-2.00) and LBW (OR 1.48, 95% CI: 0.90-2.42) between stimulated and unstimulated IVF cycles. There was no significant difference in the risk of the adverse perinatal outcomes after adjusting for potential confounders; PTB (adjusted odds ratio (aOR) 1.43, 95% CI: 0.91-2.26) and LBW (aOR 1.58, 95% CI: 0.96-2.58). LIMITATIONS, REASONS FOR CAUTION Although the analysis was adjusted for a number of important confounders, the dataset had no information on smoking, body mass index (BMI) and the medical history of women during pregnancy to allow adjustment. Anonymized nature of the dataset did not make it permissible to analyse one cycle per woman. Given the smaller number of perinatal events with unstimulated IVF, a larger study is needed to investigate further. WIDER IMPLICATIONS OF THE FINDINGS Analysis of this large dataset demonstrates that ovarian stimulation has a vital role in maximizing efficacy of IVF. Although there were no significant differences for PTB and LBW following stimulated compared to unstimulated IVF, the CIs were wide enough to include possible clinically important effects. STUDY FUNDING/COMPETING INTEREST(S) No funding was obtained. There are no competing interests to declare
La 'circunstancia' de 'Herederos y Pretendientes
No full textIn June 2010, the Ortega y Gasset Foundation hosted a Conference about the “Spanish Philosophical Transition” in order to debate the book of Francisco Vázquez, La filosofía española. Herederos y Pretendientes. Una lectura sociológica (1963-1990), recently published. This paper is the author’s response to criticism raised in the Conference and to published reviews received by this book. First, the author summarized the argument of Herederos y pretendientes. Secondly he responds and takes into account the most important objections against the book’s hypothesis and methodology. Finally the author evaluates the favorable judgments received by the book and suggests the limits of the historian’s task.Fundación Ortega y Gasset-Marañó
Author self-citation in orthodontics is associated with author origin and gender.
No full textBACKGROUND
The aims of this bibliometric study were to determine author self-citation trends in high-impact orthodontic literature and to investigate possible association between self-citation and publication characteristics.
METHODS
Six orthodontic journals with the highest impact factor as ranked by 2017 Journal Citation Reports were screened for a full publication year (2018) for original research articles, reviews, and case reports. Eligible articles were scrutinized for article and author characteristics and citation metrics. Univariable and multivariable negative binomial regression was used to examine associations between self-citation incidence and publication characteristics.
RESULTS
Medians for author self-citation rate of the most self-citing authors and self-citations were 3.03% (range 0-50) and 1 (range 0-19), respectively. In the univariable analysis, there was no association between self-citation counts and study type (P = 0.41), article topic (P = 0.61), number of authors (P = 0.62), and rank of authors (P = 0.56). Author origin (P = 0.001), gender (P = 0.001) and journal (P = 0.05) were associated with self-citation counts and in the multivariable analysis only origin and gender remained strong self-citation predictors. Asian authors and females self-cited significantly less often than all other regions and male authors.
CONCLUSIONS
Authors in orthodontics do not self-cite at a frequency that suggests potential citation manipulation. Author origin and gender were the only variables associated with citations counts. More bibliometric research is necessary to draw solid conclusions about author self-citation trends in orthodontic literature
EXTRACCIÓN DE XILENOS DE MUESTRAS LÍQUIDAS POR EL MÉTODO ALGAWI-JAFFAR-KHALAF PARA EL ANÁLISIS ESPECTROFOTOMÉTRICO
No full textEl presente trabajo se buscó, analizó y se replicó un método de extracción de Xilenos de hidrocarburos líquidos para su análisis en el espectrofotómetro. El ensayo se lo realizó en los laboratorios del CEANID (Centro de Análisis, Investigación y Desarrollo) dependiente de la UAJMS, se analizaron 3 métodos de extracción, de los cuales el método Algawi-Jaffar-Khalaf fue el implementado por su bajo coste y factibilidad. Al método establecido se realizaron modificaciones de equipos y materiales para adaptarlo a la realidad del laboratorio. Se realizaron pruebas de porcentaje de recuperación de xilenos en la gasolina especial fortificada con xileno puro, de estas pruebas se pudo conocer que el mayor porcentaje de extracción fue de 62%, Se realizaron pruebas a muestras líquidas obtenidas de la pirólisis catalítica, cada una con su réplica obteniendo concentraciones muy cercanas con diferencias abajo del 4mg/L siendo la muestra 3 la que mayor se acercaba con su réplica con un valor de 30.593 mg/L y la réplica con un valor de 30.502 mg/L. El mayor porcentaje de pérdida en las muestras de gasolina fue de 18% y en las muestras de pirólisis de 35 %, esto debido a la volatilidad de los compuestos, en el caso de la gasolina, y por las impurezas de las muestras, en el caso del líquido de pirólisis
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