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Ammoniteand bivalve-based biostratigraphy and Panboreal correlation of the Volgian Stage

Science China Earth Sciences 2009年第12期52卷 1890-1909页

作者： ROGOV Mikhail ZAKHAROV victor Geological Institute of RAS Pyzhevski lane 7 Moscow 119017 Russia

The current ammonite- and buchiid-based biostratigraphical successions of the Volgian Stage are outlined, with an analysis of the most important data that support correlation throughout the Panboreal Superrealm. Updated ammonite zonal schemes were proposed for the Volgian of the type region (the Russian Platform) and Svalbard. The lower Volgian successions in all areas except the Russian Platform, with its eudemic virgatitid lineage and Submediterranean faunal elements, were dominated by Pectinatites and Eosphinctoceras-Subdichotomoceras. The last two genera were especially common eastwards from the Ural Mountains. During the middle Volgian, provincialism developed quickly within the ammonites, and unified assemblages with early Palvovia and Dorsoplanites at the base of the substage were replaced by numerous local eudemic faunas. Despite this, migrations of species of Crendonites, Laugeites, Epivirgatites Epipallasiceras, Epilaugeites, and Taimyrosphinctes occurred at regular intervals and these enable precise correlations between the faunal sub-provinces. The zonation of the upper Volgian is mainly based upon the succession of Craspedites (on Subcraspedites in England and North Sea), and can be traced throughout the Arctic. Zonation based on the bivalve Buchia enables correlations to be made between the successions over much of the Northern Hemisphere, including Northern California, British Columbia, Arctic areas, and the Russian Platform. Each substage of the Volgian is characterized by buchiids with different types of the ontogenetic development. Research on the infrazonal subdivision of the Volgian Stage based on buchiids is currently in progress. Our analyses of the ammonite and buchiid successions of the Panboreal Superrealm lead us to conclude that there are no major faunal gaps in Volgian successions of the Russian Platform and Northern Siberia.

关键词： Volgian Portlandian Panboreal Superrealm ammonites buchiids correlation.

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The Oceanus Borealis of ancient Mars

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National Science Review 2023年第9期10卷 234-235页

作者： victor R.Baker Departments of Hydrology and Atmospheric Sciences Planetary Sciences and Geosciences University of Arizona

Fifty years ago,the Mariner 9 spacecraft revealed that the Martian surface has a great planetary dichotomy separating heavily cratered southern highlands from a huge area of more lightly cratered northern *** this discovery,informal hypothesizing by geologists considered the possibility of an Earth-like water body occupying the northern lowland Martian plains.

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Post Episiotomy Morbidity among Parturient in Alex Ekwueme Federal University Teaching Hospital Abakaliki, Ebonyi State

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Open Journal of Obstetrics and Gynecology 2024年第8期14卷 1144-1160页

作者： John Chinedu Obasi Ayodele Adegbite Olaleye Boniface N. Ejikeme John O. Egede Charles Nwambeke Edene Enemma Christian Enemma victor Onuchukwu Emmanuel Onyekelu Nathan C. Ekpe Wendy Oliobi Emmanuel C. Uwakwe Department of Obstetrics and Gynaecology Alex Ekwueme Federal University Teaching Hospital AbakalikiNigeria

Background: Episiotomy is a very common obstetric surgery, and it could be associated with serious complications. However, these complications largely are not noticed due to the shift of attention from mother to baby, after a successful delivery. Objective: To identify the morbidities associated with episiotomies and factors associated with such morbidities. Method: This was a questionnaire based cross sectional descriptive study among women who attended the Obstetric Department of Alex Ekwueme Federal University Teaching Hospital Abakaliki Ebonyi State, between 1st July and 31st Nov, 2023. The study population consisted of parturients who had episiotomies in their previous confinements, attending either the antenatal clinic or the postnatal clinic at Alex Ekwueme Federal University Teaching Hospital Abakaliki Ebonyi State. Results: Macrosomia was the most common indication of episiotomy at a rate of 31.6%. The majority of episiotomies were performed on the parturients in their first confinement at a rate of 64.5% and the majority of repairs were performed by the Registrar at a rate of 65.0%. Informed consent was obtained from 45.79% of parturients while 54.21% were not informed before the episiotomy was administered. Only 55.3% of the parturient received analgesia before episiotomy was administered. The majority of the parturients had their episiotomy repaired between 10 - 15 minutes at a rate of 40.3%. Postoperative pain at the rate of 44.5% was the most common complication and dyspareunia as a form of sexual complication was the commonest at a rate of 31.3%. Conclusion: The parturient needs to be properly counselled before administration of episiotomy and adequate analgesia should be given, as episiotomy is a surgical procedure. Proper training of health workers on both the technique of administering and repairing episiotomy is important. Restrictive use of routine episiotomy in primigravidae is advised to reduce the rate of episiotomy.

关键词： Episiotomy Vulva Pains Primigravidae Morbidities Analgesia

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Bohr–Sommerfeld Levels for Quantum Completely Integrable Systems

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Acta Mathematica Sinica,English Series 2021年第11期37卷 1743-1750页

作者： victor GUILLEMIN Zuo Qin WANG Department of Mathematics Massachusetts Institute of TechnologyCambridgeMA 02139USA School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026P.R.China

In this paper we will show how the Bohr–Sommerfeld levels of a quantum completely integrable system can be computed modulo O(h^(∞))by an inductive procedure starting at stage zero with the Bohr–Sommerfeld levels of... 详细信息

关键词： Semiclassical asymptotics Bohr-Sommerfeld levels Quantum completely integrable system

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On periodic groups with prescribed orders of elements

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Science China Mathematics 2009年第2期52卷 311-317页

作者： MAZUROV victor Danilovich Sobolev Institute of Mathematics Siberian Branch of Russian Academy of Sciences

This is a survey of results and open problems concerning the structure of periodic group with prescribed orders of their elements. In particular, an outline of a proof of the following recent result is given: every pe... 详细信息

关键词： spectrum periodic group local finiteness 20F50

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Fast rectangular matrix multiplication and some applications

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Science China Mathematics 2008年第3期51卷 389-406页

作者： victor Y PAN Department of Mathematics and Computer Science.Lehman College City University of New York BronxNew York 10468 USA

We study asymptotically fast multiplication algorithms for matrix pairs of arbitrary dimensions, and optimize the exponents of their arithmetic complexity bounds. For a large class of input matrix pairs, we improve the known exponents. We also show some applications of our results: (i) we decrease from O(n 2 + n 1+o(1)logq) to O(n 1.9998 + n 1+o(1)logq) the known arithmetic complexity bound for the univariate polynomial factorization of degree n over a finite field with q elements; (ii) we decrease from 2.837 to 2.7945 the known exponent of the work and arithmetic processor bounds for fast deterministic (NC) parallel evaluation of the determinant, the characteristic polynomial, and the inverse of an n × n matrix, as well as for the solution to a nonsingular linear system of n equations; (iii) we decrease from O(m 1.575 n) to O(m 1.5356 n) the known bound for computing basic solutions to a linear programming problem with m constraints and n variables.

关键词： rectangular matrix multiplication asymptotic arithmetic complexity bilinear algorithm polynomial factorization over finite fields 68Q25 11Y16

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Tunable electrochemistry of gold-silver alloy nanoshells

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Nano Research 2018年第12期11卷 6336-6345页

作者： Lorenzo Russo victor Puntes Arben Merkoci Catalan Institute of Nanoscience and Nanotechnology (ICN2) CSIC and BISTCampus UABBellaterra08193BarcelonaSpain Universitat Autonoma de Barcelona (UAB) Campus UABBellaterra08193BarcelonaSpain Vail d'Hebron Institut de Recerca (VHIR) 08035BarcelonaSpain Institucio Catalana de Recerca i Estudis Avancats (ICREA) P Llub Companys 2308010BarcelonaSpain

The widespread and increasing interest in enhancing biosensing technologies by increasing their sensitivities and lowering their costs has led to the exploration and application of complex nanomaterials as signal transducers and enhancers. In this work, the electrochemical properties of monodispersed AuAg alloy nanoshells (NSs) with finely tunable morphology, composition, and size are studied to assess their potential as electroactive labels. The controlled corrosion of their silver content, caused by the oxidizing character of dissolved oxygen and chlorides of the electrolyte, allows the generation of a reproducible electrochemical signal that is easily measurable through voltammetric techniques. Remarkably, the underpotential deposition of dissolved Ag+ catalyzed on AuAg NS surfaces is observed and its dependence on the nanoparticle morphology, size, and elemental composition is studied, revealing a strong correlation between the relative amounts of the two metals. The highest catalytic activity is found at Au/Ag ratios higher than ≈ 10, showing how the synergy between both metals is necessary to trigger the enhancement of Ag+ reduction. The ability of AuAg NSs to generate an electrocatalytic current without the need for any strong acid makes them an extremely promising material for biosensing applications.

关键词： Au nanoshells nanoparticles surface chemistry underpotential deposition

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Determining short chain fatty acids in sewage sludge hydrolysate: A comparison of three analytical methods and investigation of sample storage effects

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Journal of Environmental Sciences 2014年第4期26卷 926-933页

作者： victor Ibrahim Tobias Hey Karin Jonsson VA SYD SE-201 21 Malmo Sweden Water and Environmental Engineering Department of Chemical Engineering Lund University SE-21100 Lund Sweden

In anaerobic digestion, the production of short-chain fatty acids （SCFAs） can be beneficial or harmful to the overall process, depending on the concentration of accumulated acids. Therefore, the accurate determination of the SCFA concentration in both fresh and stored sludge hydrolysates is important. To select a suitable method for monitoring SCFAs during the anaerobic digestion of sewage sludge, the accuracy of three available analytical methods, including 5 pH point acid titration （TITRA5）, gas chromatography （GC）, and spectrophotometry, were compared in the present study. The results revealed that TITRA5 and GC displayed better agreement in the achieved measurements and higher precision and accuracy than the spectrophotometric assay, as supported by the application of different statistical models. TITRA5 excelled in titrating unfiltered hydrolysate while simultaneously measuring the alkalinity, whereas the GC method provided detailed information on the contribution of different fatty acids to the total acidity. In contrast, the spectrophotometric assay suffered from many forms of interference, depending on the sample＇s matrix. SCFA production followed the pattern of enzymatic reactions and fitted the Michaelis-Menten model. In addition to promoting TITRA5 as an accurate and robust analytical tool for routine SCFA analyses, this comparative study also demonstrated the possibility of storing hydrolysate samples at different temperatures and durations without altering the SCFA measurements.

关键词： five pH point titration gas chromatography spectrophotometry short-chain fatty acids sludge hydrolysis sample storage

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Epstein-Barr virus:Silent companion or causative agent of chronic liver disease?

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World Journal of Gastroenterology 2010年第33期16卷 4130-4134页

作者： Mihaela Petrova victor Kamburov Clinic of Gastroenterology Ministry of Interior Gastroenterology Division First Multiprofile Hospital for Active Treatment

The Epstein-Barr virus(EBV)has an important and multifaceted role in liver *** a member of the herpes virus family,EBV establishes a persistent infection in more than 90%of *** acute hepatitis during primary infection,many clinical syndromes of interest for the hepatologist are associated with EBV *** role of EBV in the evolution of chronic hepatitis from hepatotropic viruses is *** EBVassociated hepatitis is suspected in immunocompetent adults with compatible serology,suggestive histology and detection of the viral genome in the liver and/or increase of specific circulating cytotoxic *** is the main cause of post-transplant lymphoproliferative disorders which occur in up to 30%of ***-driven lymphoproliferative diseases are also recognized in non-immunocompromised patients and liver is involved in up to a third of the *** implicated in the pathogenesis of different tumors,EBV has a disputable role in hepatocellular carcinoma *** research is required in order to establish or reject the role of EBV in human liver *** paper attempts to discuss the range of EBV-associated chronic liver diseases in immunocompetent patients,from mild,self-limiting mononuclear hepatitis to liver cancer.

关键词： Epstein-Barr virus Chronic hepatitis Liver disease Chronic active Epstein-Barr virus Post-transplant lymphoproliferative disorder Infectious mononucleosis

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Breastfeeding and chronic HBV infection: Clinical and social implications

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World Journal of Gastroenterology 2010年第40期16卷 5042-5046页

作者： Mihaela Petrova victor Kamburov Clinic of Gastroenterology Ministry of Interior Department of Gastroenterology First Multi Profile Hospital for Active Treatment

Mother-to-child transmission of hepatitis B virus (HBV) is among the most important causes of chronic HBV infection and is the commonest mode of transmission worldwide. Currently, the presence of HBsAg, HBeAg and HBV DNA in breast milk is confirmed. Several studies have reported that breastfeeding carries no additional risk that might lead to vertical transmission. Beyond some limitations, the surveys have not demonstrated any differences in HBV transmission rate regarding feeding practices in early childhood. Promotion of breastfeeding is substantial, especially for low-income individuals and regions with uncertain, unfeasible, and unsafe water supplies. Lactoferrin, minimal inflammation or activation within the infant gut during exclusive breastfeeding, and nonspecific biological molecules in the milk are identified as major factors of breast-milk defense. This review discusses preemptive antiviral therapy during pregnancy and lactation. Long-term follow up of breast-milk HBV concentrations and correlation with serum viral load; nucleos(t)ide analogue concentrations in breast milk in HBV-positive mothers in the setting of chronic HBV infection; safety of antiviral therapy during pregnancy and lactation; and the difference in viral load in the milk in exclusive or non-exclusive breastfeeding are still open questions. The paper reviews the current data and outlines the course of further investigation into this often underestimated issue.

关键词： Breastfeeding Lamivudine Tenofovir Hepatitis B virus Chronic hepatitis B

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