Alterations in venous blood flow of lower uterus segment and cervix of uterus at physiological course of preliminary period

Research objective. The objective of this research is the study of venous blood flow parameters of lower uterus segment and cervix of uterus at the physiological course of preliminary period. Material and methods. The study was based on the investigation of the course of preliminary period of 90 patients with physiological delivery at term. Results. There is a growing rate of venous blood flow of lower uterus segment and cervix of uterus at rest as well as at peak of contractions. Conclusion. Veins are transformed into structures similar to lacunae at the physiological course of preliminary period. There is a growing rate of venous blood flow of lower uterus segment and cervix of uterus which results in blood storage and seems to be one of the mechanisms leading to cervical dilatation

Current views on the possibility of cervical insufficiency correction

The main role in spontaneous abortion in 2nd and 3d trimesters is assigned to cervical insufficiency. According to a number of researchers, bed rest, elevated lower limbs, restriction of physical activity, tocolysis, antibacterial therapy do not affect the prolongation of pregnancy and are ineffective for preventing premature spontaneous labor. Correction of cervical insufficiency can be carried out by a vaginal form of progesterone, cerclage, pessary. The use of vaginal progesterone is justified in women with recurrent miscarriage, a history of premature birth, and shortening of the cervix to less than 25 mm. Indications for surgical correction are limited to patients with habitual loss of pregnancy due to cervical weakness or a history of premature birth. In the absence of significant obstetric history, cerclage has no advantages over the use of progesterone. The optimal time for cerclage is up to 20 weeks of pregnancy. Unlike progesterone cerclage has complications, the frequency and severity of which are attributable to the timing and indications for correction. Transabdominal cerclage is performed only when there is a technical impossibility of vaginal access due to the absence of a vaginal part of the cervix or after unsuccessful attempts of vaginal cerclages. Most often, the use of a pessary is associated with the diagnosis of a short cervix in terms of more than 24 weeks of gestation in the absence of an aggravated history. The combined use of gestagens, pessary and cerclage does not increase the efficiency of carrying a singleton pregnancy. Methods for the prevention of preterm delivery in multiple pregnancy, such as the introduction of a specialized outpatient service, bed rest, antibacterial therapy, progesterone, preventive cerclage or the insertion of a pessary do not change the incidence and mortality of newborns

Synthesis and research of polyfunctional silylureas used in electric deposition of tin-indium alloy

Polyfunctional silylureas were synthesized by the interaction of 3-aminopropyltriethoxysilane with isocyanates of various structures in an inert aromatic solvent. Commercially available diisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, 2,4-toluene diisocyanate were used as isocyanates. In this case, freshly distilled toluene was used as a solvent. The structures of the obtained compounds were confirmed by the data of IR and NMR1H spectroscopy. Using the synthesized compounds, formulations of compositions for electrodeposition of a tin-indium alloy on a copper wire were developed. The possibility of using silylureas of various structures as effective surfactants used in the electrodeposition of the tin-indium alloy is shown. The operational characteristics of the obtained wire were investigated, including the wire diameter, coating thickness, tensile strength, electrical resistance, and direct current electrical resistivity

Evaluating the Influence of Plate Boundary Friction and Mantle Viscosity on Plate Velocities

Lithospheric plates move over the low‐viscosity asthenosphere balancing several forces, which generate plate motions. We use a global 3‐D lithosphere‐asthenosphere model (SLIM3D) with visco‐elasto‐plastic rheology coupled to a spectral model of mantle flow at 300 km depth to quantify the influence of intra‐plate friction and asthenospheric viscosity on plate velocities. We account for the brittle‐ductile deformation at plate boundaries (yield stress) using a plate boundary friction coefficient to predict the present‐day plate motion and net rotation of the lithospheric plates. Previous modeling studies have suggested that small friction coefficients ( urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0001, yield stress urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0002 MPa) can lead to plate tectonics in models of mantle convection. Here we show that in order to match the observed present‐day plate motion and net rotation, the frictional parameter must be less than 0.05. We obtain a good fit with the magnitude and orientation of the observed plate velocities (NUVEL‐1A) in a no‐net‐rotation (NNR) reference frame with urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0003 and a minimum asthenosphere viscosity of urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0004 Pas to 1020 Pas. Our estimates of net rotation (NR) of the lithosphere suggest that amplitudes urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0005 ( urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0006/Ma), similar to most observation‐based estimates, can be obtained with asthenosphere viscosity cutoff values of urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0007 Pas to urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0008 Pas and friction coefficients urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0009

Simulating the Antarctic ice sheet in the late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project

In the context of future climate change, understanding the nature and behaviour of ice sheets during warm intervals in Earth history is of fundamental importance. The late Pliocene warm period (also known as the PRISM interval: 3.264 to 3.025 million years before present) can serve as a potential analogue for projected future climates. Although Pliocene ice locations and extents are still poorly constrained, a significant contribution to sea-level rise should be expected from both the Greenland ice sheet and the West and East Antarctic ice sheets based on palaeo sea-level reconstructions. Here, we present results from simulations of the Antarctic ice sheet by means of an international Pliocene Ice Sheet Modeling Intercomparison Project (PLISMIP-ANT). For the experiments, ice-sheet models including the shallow ice and shelf approximations have been used to simulate the complete Antarctic domain (including grounded and floating ice). We compare the performance of six existing numerical ice-sheet models in simulating modern control and Pliocene ice sheets by a suite of five sensitivity experiments. We include an overview of the different ice-sheet models used and how specific model configurations influence the resulting Pliocene Antarctic ice sheet. The six ice-sheet models simulate a comparable present-day ice sheet, considering the models are set up with their own parameter settings. For the Pliocene, the results demonstrate the difficulty of all six models used here to simulate a significant retreat or re-advance of the East Antarctic ice grounding line, which is thought to have happened during the Pliocene for the Wilkes and Aurora basins. The specific sea-level contribution of the Antarctic ice sheet at this point cannot be conclusively determined, whereas improved grounding line physics could be essential for a correct representation of the migration of the grounding-line of the Antarctic ice sheet during the Pliocene

PLISMIP-ANT, an ice-sheet model intercomparison project

In the context of future climate change, understanding the nature and behaviour of ice sheets during warm intervals in Earth history is of fundamental importance. The late Pliocene warm period (also known as the PRISM interval: 3.264 to 3.025 million years before present) can serve as a potential analogue for projected future climates. Although Pliocene ice locations and extents are still poorly constrained, a significant contribution to sea-level rise should be expected from both the Greenland ice sheet and the West and East Antarctic ice sheets based on palaeo sea-level reconstructions. Here, we present results from simulations of the Antarctic ice sheet by means of an international Pliocene Ice Sheet Modeling Intercomparison Project (PLISMIP-ANT). For the experiments, ice-sheet models including the shallow ice and shelf approximations have been used to simulate the complete Antarctic domain (including grounded and floating ice). We compare the performance of six existing numerical ice-sheet models in simulating modern control and Pliocene ice sheets by a suite of five sensitivity experiments. We include an overview of the different ice-sheet models used and how specific model configurations influence the resulting Pliocene Antarctic ice sheet. The six ice-sheet models simulate a comparable present-day ice sheet, considering the models are set up with their own parameter settings. For the Pliocene, the results demonstrate the difficulty of all six models used here to simulate a significant retreat or re-advance of the East Antarctic ice grounding line, which is thought to have happened during the Pliocene for the Wilkes and Aurora basins. The specific sea-level contribution of the Antarctic ice sheet at this point cannot be conclusively determined, whereas improved grounding line physics could be essential for a correct representation of the migration of the grounding-line of the Antarctic ice sheet during the Pliocene

Ice surface changes during recent glacial cycles along the Jutulstraumen and Penck Trough ice streams in western Dronning Maud Land, East Antarctica

Reconstructing past ice-sheet surface changes is key to testing and improving ice-sheet models. Data constraining the past behaviour of the East Antarctic Ice Sheet are sparse, limiting our understanding of its response to past, present and future climate change. Here, we report the first cosmogenic multi-nuclide (10Be, 26Al, 36Cl) data from bedrock and erratics on nunataks along the Jutulstraumen and Penck Trough ice streams in western Dronning Maud Land, East Antarctica. Spanning elevations between 741 and 2394 m above sea level, the samples have apparent exposure ages between 2 ka and 5 Ma. The highest-elevation bedrock sample indicates (near-) continuous minimum exposure since the Pliocene, with a low apparent erosion rate of 0.15 ± 0.03 m Ma−1, which is similar to results from eastern Dronning Maud Land. In contrast to studies in eastern Dronning Maud Land, however, our data show clear indications of a thicker-than-present ice sheet within the last glacial cycle, with a thinning of ∼35–120 m during the Holocene (∼2–11 ka). Difficulties in separating suitable amounts of quartz from the often quartz-poor rock-types in the area, and cosmogenic nuclides inherited from exposure prior to the last deglaciation, prevented robust thinning estimates from elevational profiles. Nevertheless, the results clearly demonstrate ice-surface fluctuations of several hundred meters between the current grounding line and the edge of the polar plateau for the last glacial cycle, a constraint that should be considered in future ice-sheet model simulations

Контактные и бесконтактные методы измерения параметров пористого кремния

In this work we have used contact and contactless techniques to measure the electrical resistivity of single crystal silicon wafers with porous layers of variable thickness synthesized on the surface. The porous layers have been synthesized on the surfaces of single crystal wafers with well pronounced microroughness pattern, either textured or grinded. We have used the classic four-probe method with a linear probe arrangement as the contact measurement technique, and the resonance microwave method based on microwave absorption by free carriers as the contactless measurement technique. Electrical resistivity distribution over the specimen surface has been mapped based on the measurement results. We have demonstrated a general agreement between the electrical resistivity distribution patterns as measured using the contact and contactless measurement techniques. To analyze the electrical resistivity scatter over the specimen surface area we have simulated the field distribution in the electrolyte during porous layer formation in a non-planar anode cell. The regularities of the electrical resistivity spatial distribution in different types of specimens are accounted for by specific porosity formation mechanisms which in turn are controlled by the initial microroughness pattern and the field distribution pattern in the electrolyte for each specific case.Бесконтактные методы измерения параметров представляют особый интерес для наноматериалов, к которым относится и пористый кремний, так как при измерении их параметров контактными методами наноструктура может быть необратимо нарушена. Актуальным вопросом является интерпретация результатов измерений параметров наноматериалов бесконтактными методами и сопоставление их с результатами, полученные с помощью традиционных контактных методов. Контактным и бесконтактным методами проведены измерения удельного электросопротивления (УЭС) образцов монокристаллических пластин кремния с созданным на их поверхности пористым слоем различной толщины. Пористый слой создавали на поверхностях монокристаллических пластин с хорошо выраженным микрорельефом: текстурированных и шлифованных. В качестве контактного был выбран классический четырехзондовый метод с линейным расположением зондов, в качестве бесконтактного — резонаторный СВЧ-метод, основанный на явлении поглощения СВЧ-излучения свободными носителями заряда. По результатам измерений построены карты распределения УЭС по площади образцов. Показано качественное совпадение картин распределения УЭС, полученных контактным и бесконтактным методом. Для анализа картины разброса значений удельного сопротивления по площади образцов проведено моделирование распределения поля в электролите при формировании пористого слоя в ячейке с непланарным анодом. Особенности пространственного распределения УЭС для каждого типа образцов объясняются особенностями механизма порообразования, которые, в свою очередь, задаются исходным микрорельефом поверхности и картиной распределения поля в электролите в данном конкретном случае