2,897 research outputs found
RESEARCHES ON THE INFLUENCE OF ROOTSTOCKS ON GROWTH AND FRUCTIFICATION OF PLUM VARIETIES
Plum is a rustic species that succeeds in minimal agrotechnic conditions and therefore has expanded extensively in the gardens of the population. Particularly favorable ecological conditions for the plum culture allow for the expansion of new varieties, recently created in our country or imported from abroad. By properly applying crop technologies, high and consistent production can be achieved to meet the needs of domestic consumption and to ensure availability for export. The researches were carried out between 2014 and 2016 within a plantation set up in 1995. The biological material used in this paper is represented by 19 plum varieties (Diana, Ialomiţa, Silvia, Piteştean, Centenar, Minerva, Flora, Carpatin, Valcea, Tita, Tuleugras, RenclodAlthan, Pescăruş, Dâmboviţa, Record and Anna Spath) grafted on 3 or 4 rootstocks (Oteşani 8, Pixy, Miroval and Roşiorvăratic). The paper aims to establish the rootstock's influence on growth and fructification within the graft / rootstock biosystem. The Oteşani 8 rootstock imprints to the studied varieties the smallest growth, while the Miroval rootstock imprints the highest growth force to the varieties studied. In all studied elements. Pixy and Roşiorvăratic varieties give to the studied varieties an average growth force compared to the other two rootstocks
Orientation-dependent binding energy of graphene on palladium
Using density functional theory calculations, we show that the binding
strength of a graphene monolayer on Pd(111) can vary between physisorption and
chemisorption depending on its orientation. By studying the interfacial charge
transfer, we have identified a specific four-atom carbon cluster that is
responsible for the local bonding of graphene to Pd(111). The areal density of
such clusters varies with the in-plane orientation of graphene, causing the
binding energy to change accordingly. Similar investigations can also apply to
other metal substrates, and suggests that physical, chemical, and mechanical
properties of graphene may be controlled by changing its orientation.Comment: 5 pages, 6 figure
Prediction of small for gestational age neonates: screening by maternal factors, fetal biometry, and biomarkers at 35-37 weeks' gestation
Background: Small for gestational age (SGA) neonates are at increased risk of perinatal mortality and morbidity, but the risks can be substantially reduced if the condition is identified prenatally, because in such cases close monitoring and appropriate timing of delivery and prompt neonatal care can be undertaken. The traditional approach of identifying pregnancies with SGA fetuses is maternal abdominal palpation and serial measurements of symphysial-fundal height, but the detection rate of this approach is less than 30%. A higher performance of screening for SGA is achieved by sonographic fetal biometry during the third trimester; screening at 30-34 weeks’ gestation identifies about 80% of SGA neonates delivering preterm but only 50% of those delivering at term, at screen positive rate of 10%. There is some evidence that routine ultrasound examination at 36 weeks' gestation is more effective than that at 32 weeks in predicting birth of SGA neonates.
Objective: To investigate the potential value of maternal characteristics and medical history, sonographycally estimated fetal weight (EFW) and biomarkers of impaired placentation at 35+0 - 36+6 weeks’ gestation in the prediction of delivery of small for gestational age (SGA) neonates.
Methods: A dataset of 124,443 prospectively examined singleton pregnancies at 11+0 - 13+6 weeks’ gestation was used to derive, through multivariable logistic regression analysis, the patient-specific prior risk for delivery of SGA neonate with birthweight <10th percentile for gestational age from maternal characteristics and medical history. A dataset of 19,209 singleton pregnancies undergoing screening at 35+0 - 36+6 weeks’ gestation was divided into a training set and a validation set. The training dataset was used to develop models from multivariable logistic regression analysis to determine whether addition of uterine artery pulsatility index (UtA-PI), umbilical artery PI (UA-PI), fetal middle cerebral artery PI (MCA-PI), maternal serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFLT) improved the performance of maternal factors and EFW in the prediction of delivery of SGA neonates. The models were then tested in the validation dataset to assess performance of screening.
Results In the training dataset, in the SGA group, compared to those with birthweight ≥10th percentile, the median multiple of the median (MoM) values of PLGF and MCA-PI were reduced, whereas UtA-PI, UA-PI and sFLT were increased. Multivariable regression analysis demonstrated that in the prediction of SGA <10th there were significant contributions from maternal factors, EFW Z-score, UtA-PI MoM, MCA-PI MoM and PlGF MoM. In the validation dataset, prediction of 90% of SGA neonates delivering within two weeks of assessment was achieved by a screen positive rate of 67% in screening by maternal factors, 23% by maternal factors and EFW and 21% by the addition of biomarkers; the respective values for prediction of SGA neonates delivering at any stage after assessment were 66%, 32% and 30%.
Conclusion: Addition of biomarkers of impaired placentation only marginally improves the predictive performance for delivery of SGA neonates achieved by maternal factors and fetal biometry at 35+0 - 36+6 weeks’ gestation
Routine assessment of cerebroplacental ratio at 35-37 weeks' gestation in the prediction of adverse perinatal outcome
Background: Third trimester studies in selected high-risk pregnancies have reported that low cerebroplacental ratio (CPR), due to high pulsatility index (PI) in the umbilical artery (UA), and or decreased PI in the fetal middle cerebral artery (MCA), is associated with increased risk of adverse perinatal outcomes.
Objective: To investigate the predictive performance of screening for adverse perinatal outcome by the cerebroplacental ratio (CPR) measured routinely at 35+6 - 36+6 weeks’ gestation.
Methods: This was a prospective observational study in 47,211 women with singleton pregnancies undergoing routine ultrasound examination at 35+6 - 36+6 weeks’ gestation, including measurement of UA-PI and MCA-PI. The measured UA-PI and MCA-PI and their ratio were converted to multiples of the median (MoM) after adjustment for gestational age. Multivariable logistic regression analysis was used to determine whether CPR improved the prediction of adverse perinatal outcome that was provided by maternal characteristics, medical history and obstetric factors. The following outcome measures were considered: first, adverse perinatal outcome consisting of stillbirth, neonatal death or hypoxic ischemic encephalopathy grades 2 and 3, second, presence of surrogate markers of perinatal hypoxia consisting of umbilical arterial or venous cord blood pH ≤7 and ≤7.1, respectively, 5-minute Apgar score 24 hours, third, cesarean section for presumed fetal distress in labor, and fourth, neonatal birthweight <3rd percentile for gestational age.
Results: Low CPR was associated with increased risk of adverse perinatal outcome, presence of surrogate markers of perinatal hypoxia, cesarean section for presumed fetal distress in labor and birth of neonates with birthweight <3rd percentile. However, multivariable regression analysis demonstrated that the prediction of these adverse outcomes by maternal demographic characteristics and medical history was only marginally improved by the addition of CPR. The performance of low CPR in the prediction of each adverse outcome was poor, with detection rates of 13–26% and false positive rate of about 10%. In appropriate for gestational age (AGA) neonates with birthweight ≥10th percentile the predictive accuracy of CPR was low with positive and negative likelihood ratios (LRs) ranging from 1.21 to 1.82, and 0.92 to 0.98, respectively; although the accuracy was better in small for gestational age (SGA) neonates this was also low with positive LRs of 1.31 to 2.26 and negative LRs of 0.69 to 0.92. Similar values were obtained in fetuses classified as SGA and AGA according to the estimated fetal weight. In the prediction of adverse outcomes within two weeks, rather than at any stage, after assessment the detection rate was higher but this was achieved at higher false positive rate and therefore similar positive and negative LRs.
Conclusion: In pregnancies undergoing routine antenatal assessment at 35+0 - 36+6 weeks’ gestation measurement of CPR provides poor prediction of adverse perinatal outcome in both SGA and AGA fetuses. Consequently, there is no justification in a shift of the focus of prenatal care from identification of pregnancies with low estimated fetal weight to that of pregnancies with low CPR
Prediction of small-for-gestational-age neonates at 35-37 weeks' gestation: contribution of maternal factors and growth velocity between 20 and 36 weeks
Objective: To evaluate the performance of ultrasonographic estimated fetal weight (EFW) at 35+0 - 36+6 weeks’ gestation in the prediction of small for gestational age (SGA) neonates and assess the additive value of first, maternal risk factors and second, fetal growth velocity between 20 and 36 weeks’ gestation in improving such prediction.
Methods: This was a prospective study of 44,043 singleton pregnancies that had undergone routine ultrasound examination at 19+0 - 23+6 and at 35+0 - 36+6 weeks’ gestation. Multivariable logistic regression analysis was used to determine whether addition of maternal risk factors and growth velocity, defined by a difference in EFW Z-scores or fetal abdominal circumference (AC) Z-scores between the third and second trimester scans divided by the time interval between them, improved the performance of EFW at 35+0 - 36+6 weeks in the prediction of delivery of SGA neonates with birthweight <10th and <3rd percentiles within two weeks and at any stage after assessment.
Results: Screening by EFW at 35+0 - 36+6 weeks’ gestation <10th percentile predicted 63.4% (95% CI 62.0, 64.7) of neonates with birthweight <10th percentile and 74.2% (95% CI 72.2, 76.1) of neonates with birthweight <3rd percentile born at any stage after assessment, at screen positive rate of 10%. The respective values for SGA neonates born within two weeks of assessment were 76.8% (95% CI 74.4, 79.0) and 81.3% (95% CI 78.2, 84.0). In the group of fetuses with EFW <10th percentile, 43.7% were born with birthweight ≥10th percentile. For a desired 90% detection rate of SGA neonates delivering at any stage after assessment the necessary screen positive rate would be 33.7% for SGA <10th percentile and 24.4% for SGA <3rd percentile. Multivariable logistic regression analysis demonstrated that in the prediction of SGA neonates with birthweight <10th and <3rd percentiles there was a significant contribution from EFW Z-score at 35+0 - 36+6 weeks’ gestation, maternal risk factors and AC growth velocity, but not EFW growth velocity. However, the area under the receiver operating characteristic curves for SGA neonates in screening by maternal risk factors and EFW Z-score was not improved by addition of AC growth velocity.
Conclusion: Screening for SGA neonates by EFW at 35+0 - 36+6 weeks’ gestation and use of a cut-off of the 10th percentile predicts 63% of affected neonates. Prediction of 90% of SGA neonates necessitates classification of about 35% of the population as being screen positive use of the 35th percentile cut-off in EFW. The predictive performance of EFW is not improved by addition of estimated growth velocity between the second and third trimesters of pregnancy
Prediction of small-for-gestational-age neonates at 35-37 weeks' gestation: contribution of maternal factors and growth velocity between 32 and 36 weeks
Objective: To assess the additive value of fetal growth velocity between 32 and 36 weeks’ gestation on the performance of ultrasonographic estimated fetal weight (EFW) at 35+0 - 36+6 weeks’ gestation for prediction of small for gestational age (SGA) neonates and adverse perinatal outcome.
Methods: This was a prospective study of 14,497 singleton pregnancies that had undergone routine ultrasound examination at 28+0 - 34+6 and at 35+0 - 36+6 weeks’ gestation. Multivariable logistic regression analysis was used to determine whether addition of growth velocity, defined by a difference in EFW and abdominal circumference (AC) Z-scores between the early and late third trimester scans divided by the time interval between them, improved the performance of EFW at 35+0 - 36+6 weeks in the prediction of first, delivery of SGA neonates with birthweight <10th and <3rd percentiles within two weeks and at any stage after assessment and second, composite of adverse perinatal outcome defined as stillbirth, neonatal death or admission to the neonatal unit for ≥48 hours.
Results Multivariable logistic regression analysis demonstrated that significant contributors to prediction of SGA neonates were EFW Z-score at 35+0 - 36+6 weeks’ gestation, fetal growth velocity by either AC or EFW Z-scores and maternal risk factors. The area under the receiver operating characteristic curves (AUROC) and detection rate (DR) with 95% confidence interval, at 10% screen positive rate, for prediction of SGA neonates <10th percentile born within two weeks of assessment achieved by EFW Z-score at 35+0 - 36+6 weeks (AUROC 0.938, 0.928 - 0.947; DR 80.7, 77.6 - 83.9) were not significantly improved by addition of EFW growth velocity and maternal risk factors (AUROC 0.941, 0.932 - 0.950; p=0.061; DR 82.5, 79.4 - 85.3). Similar results were obtained when growth velocity was defined by AC rather than EFW growth velocity. Similarly, there was no significant improvement in AUROC and DR, at 10% screen positive rate, for prediction of SGA neonates <10th percentile born at any stage after assessment or SGA neonates <3rd percentile born within two weeks or at any stage after assessment achieved by EFW Z-score at 35+0 - 36+6 weeks by addition of maternal factors and either EFW growth velocity of AC growth velocity. Multivariable logistic regression analysis demonstrated that the only significant contributor to adverse perinatal outcome was maternal risk factors. Multivariable logistic regression analysis in the group with EFW <10th percentile demonstrated that significant contribution to prediction of birth of neonates with birthweight <10th and <3rd percentiles and adverse perinatal outcome was provided by EFW Z-score at 35+0 - 36+6 weeks, but not by AC growth velocity <1st decile.
Conclusion: The predictive performance of EFW at 35+0 - 36+6 weeks’ gestation for birth of SGA neonates and adverse perinatal outcome is not improved by addition of estimated growth velocity between 32 and 36 weeks’ gestation
ALEX Fetal Medicine Foundation reference ranges for umbilical artery and middle cerebral artery pulsatility index and cerebroplacental ratio
Objective: To develop reference ranges with gestational age for the pulsatility index in the umbilical artery (UA-PI) and fetal middle cerebral artery (MCA-PI and the cerebroplacental ratio (MCA-PI / UA-PI) and examine the maternal characteristics and medical history that affect these measurements.
Patients and methods: This was a cross-sectional study of 72,417 pregnancies undergoing routine ultrasound examination at 20+0 to 22+6 weeks’ gestation (n=3,712), or at 31+0 to 33+6 weeks (n=29,035) or at 35+0 to 36+6 weeks (n=37,282) or at 41+0 to 41+6 weeks (n=2,388). For the purpose of this study we included data for only one of the second or third trimester visits. The inclusion criteria were singleton pregnancy, dating by fetal crown-rump length at 11+0 to 13+6 weeks’ gestation, livebirth of morphologically normal neonate and ultrasonographic measurements by sonographers that had received the Fetal Medicine Foundation Certificate of competence in Doppler ultrasound. Since the objectives of the study were to establish reference ranges, rather than normal ranges, and to examine factors from maternal characteristics and medical history that affect these measurements, we included all pregnancies having routine ultrasound examinations irrespective of whether the mothers had a pre-existing medical condition, such as diabetes mellitus, or a pregnancy complication, such as preeclampsia or suspected fetal growth restriction. Median and standard deviation (SD) models were fitted between UA-PI, MCA-PI and CPR and gestational age. Assessment of goodness of fit of the models was by inspection of quantile to quantile (q-q) plots of z-scores calculated via the mean and SD models. The distributions of MCA PI, UA PI and CPR z-scores were examined in relation to maternal characteristics and medical history.
Results: The relationship between the median and gestation age was linear for UA-PI and cubic for MCA-PI and CPR and the SD was log quadratic for all three. MCA-PI and CPR increased with gestational age from 20 weeks’ gestation to reach a peak at around 32 and 34 weeks’ respectively, and decreased thereafter, whereas UA-PI decreased linearly with gestation from 20 to 42 weeks. Compared to the general population, significant deviations in MoM values of UA-PI, MCA-PI and CPR were observed in subgroups of maternal age, BMI, racial origin, method of conception and parity.
Conclusion: The study established new reference ranges of UA-PI, MCA-PI and CPR with gestational age and reports maternal characteristics and medical history that affect these
measurements
More Than 1700 Years of Word Equations
Geometry and Diophantine equations have been ever-present in mathematics.
Diophantus of Alexandria was born in the 3rd century (as far as we know), but a
systematic mathematical study of word equations began only in the 20th century.
So, the title of the present article does not seem to be justified at all.
However, a linear Diophantine equation can be viewed as a special case of a
system of word equations over a unary alphabet, and, more importantly, a word
equation can be viewed as a special case of a Diophantine equation. Hence, the
problem WordEquations: "Is a given word equation solvable?" is intimately
related to Hilbert's 10th problem on the solvability of Diophantine equations.
This became clear to the Russian school of mathematics at the latest in the mid
1960s, after which a systematic study of that relation began.
Here, we review some recent developments which led to an amazingly simple
decision procedure for WordEquations, and to the description of the set of all
solutions as an EDT0L language.Comment: The paper will appear as an invited address in the LNCS proceedings
of CAI 2015, Stuttgart, Germany, September 1 - 4, 201
Two-stage approach for prediction of small-for-gestational-age neonate and adverse perinatal outcome by routine ultrasound examination at 35-37 weeks' gestation
Background: Justification of prenatal screening for small for gestational age (SGA) fetuses near term is based on first, evidence that such fetuses / neonates are at increased risk of stillbirth and adverse perinatal outcome, and second, the expectation that these risks can be reduced by medical interventions, such as early delivery. However, there are no randomized studies demonstrating that routine screening for SGA fetuses and appropriate interventions in the high risk group can reduce adverse perinatal outcome. Before such meaningful studies can be undertaken it is essential that first, the best approach for effective identification of SGA neonates is determined, and second, the contribution of SGA neonates to the overall rate of adverse perinatal outcome is established. In a previous study of pregnancies that had undergone routine ultrasound examination at 35+0 36+6 weeks’ gestation, we found that first, screening by estimated fetal weight (EFW) 85% of SGA neonates requires use of EFW <40th percentile.
Objectives: First, to examine the contribution of SGA fetuses to the overall rate of adverse perinatal outcome and second, to propose a two stage approach for prediction of SGA neonates at routine ultrasound examination at 35+0 36+6 weeks’ gestation.
Methods: This was a prospective study of 45,847 singleton pregnancies that had undergone routine ultrasound examination at 35+0 36+6 weeks’ gestation. First we examined the relationship between birthweight percentile and adverse perinatal outcome, defined as stillbirth, neonatal death or admission to the neonatal unit for ≥48 hours. Second, we used a two stage approach for prediction of SGA neonates and adverse perinatal outcome; in the first stage fetal biometry was used to distinguish pregnancies at very low risk (EFW ≥40th percentile) and those at increased risk (EFW 4 weeks after assessment was determined. We propose that the high risk group would require monitoring from initial assessment to delivery, the intermediate risk group would require monitoring from two weeks after initial assessment to delivery, the low risk group would require monitoring from four weeks after initial assessment to delivery, and the very low risk group would not require any further reassessment.
Results: First, although in babies with low birthweight (4 (40% and 30%) from assessment. Third, improved performance of screening, especially for those delivering after two weeks from assessment, is potentially achieved by a proposed new approach for stratifying pregnancies into management groups based on findings of EFW and Doppler indices (prediction of birthweight 4 weeks from assessment: 89% and 75%, 83% and 74% and 88% and 82%, respectively). Fourth, the predictive performance for adverse perinatal outcome of EFW 4 weeks from assessment, respectively) and this is improved by the proposed new approach (31%, 22% and 29%).
Conclusion: The study presents an approach for stratifying the pregnancies undergoing routine ultrasound examination at 35+0 36+6 weeks’ gestation into four management groups based on findings of EFW and Doppler indices. This approach can potentially have a higher predictive performance for SGA neonates and adverse perinatal outcome than screening by EFW <10th percentile
PARTICULARITIES OF THE GRAFT-ROOTSTOCK BIOSYSTEM IN THE VARIETY OF APRICOT NJA 19
Of the species of trees grown in the temperate climate area, apricot is considered one of the most valuable, due primarily to all the excellent taste and the very pleasant flavor of the fruit, the fine consistency and juice of the pulp, which in most cases has a special flavor. In 2017, within an apricot plantation set up in 2000, in a family garden, researches were carried out on how trees grow in the root system. The biological material was the N.J.A. 19 variety grafted on the cherry plum, the trees in the plantation being led in the form of an improved vessel. The purpose of the research is to determine how the roots are arranged in the soil, the depth at which the large mass of the root system is distributed, and the weighting of each thickness category, on depth ranges. Apricot variety N.J.A. 19 shows a good development of the underground part, of the root system, respectively, which is distributed to a depth of 90 cm at a distance of 1 m from the trunk or up to a depth of 70 cm at a distance of 2 m towards the trunk
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