Результаты теоретических и опытных работ по изучению механизма работы буровых компоновок со смещенным центром масс поперечного сечения

Актуальность работы: необходимость повышения эффективности бурения геологоразведочных скважин в сложных горно-геологических условиях, в том числе связанных с естественным искривлением скважин. Цель исследования: разработка методики использования и конструкций буровых компоновок со смещенным центром масс (тяжести) поперечного сечения, позволяющих повысить эффективность бурения геологоразведочных скважин. Методы исследования: аналитические исследования, опытно-конструкторские работы и экспериментальные опытные работы. Результаты. Разработаны теоретические положения, методика применения и конструкции буровых компоновок со смещенным центром тяжести поперечного сечения; проведены производственные испытания различных конструкций буровых компоновок со смещенным центром тяжести поперечного сечения при различных способах бурения. Выводы. На основе разработанной модели движения буровых компоновок со смещенным центром тяжести поперечного сечения получены аналитические зависимости для расчета величин эксцентриситета поперечного сечения буровых компоновок, обеспечивающие их вращение вокруг оси скважины (вид Ф1), а также длину вовлекаемого в режим вращения Ф1 участка колонны, что позволяет создавать компоновки бурильной колонны, способные работать в более благоприятном режиме и обеспечивать повышение эффективности бурового процесса. На основе стандартных снарядов со съемным керноприемником типоразмера HQ разработаны и изготовлены трубы со смещенным центром тяжести, которые испытаны на производственных скважинах в составе компоновки, в которой размещено три трубы со смещенным центром тяжести поперечного сечения. Результаты испытаний показали, что в составе высокосбалансированных бурильных колонн снаряда со съемным керноприемником эффективно применение труб со смещенным центром тяжести: достигается снижение интенсивности естественного искривления скважин, снижается вибрация и затраты мощности на работу бурильной колонны.Relevance of the research is the necessity to increase the efficiency of drilling prospecting wells in difficult mining-and-geological conditions, including those connected with a natural curvature of wells. The aim of the research is to develop a technique of using and designs of boring configurations with the displaced cross section mass center which allow increasing the efficiency of drilling the prospecting wells. Research methods: analytical researches, developmental works and experimental skilled works. Results. The authors have developed the theoretical regulations, a technique of application and a design of boring configurations with the displaced cross section mass center and carried out the production tests of various designs of boring configurations of with the displaced cross section mass center when drilling. Conclusions. Based on the developed model of movement of boring configurations with the displaced center of gravity of cross section the authors obtained the analytical dependences for calculating the sizes of eccentricity of boring configuration cross section providing their rotation round a well axis (Ф1 type), as well as the length of the column part involved in the rotation mode Ф1 that allows developing the configurations of a boring column capable of operating in more favorable mode and providing the increase of boring efficiency. Based on standard shells with the removable core receiver of a standard size of HQ the pipes with the displaced cross section mass center were developed and produced. They were tested on production wells as a part of configuration in which three pipes with the displaced cross section mass center were placed. The results of the tests showed that it is efficient to apply the pipes with the displaced cross section mass center as a part of the high-balanced boring columns as the decrease in intensity of natural curvature of wells is reached, vibration and costs of power for boring column operation decrease

Intra-Host Evolution Analyses in an Immunosuppressed Patient Supports SARS-CoV-2 Viral Reservoir Hypothesis.

Throughout the SARS-CoV-2 pandemic, several variants of concern (VOCs) have been identified, many of which share recurrent mutations in the spike glycoprotein's receptor-binding domain (RBD). This region coincides with known epitopes and can therefore have an impact on immune escape. Protracted infections in immunosuppressed patients have been hypothesized to lead to an enrichment of such mutations and therefore drive evolution towards VOCs. Here, we present the case of an immunosuppressed patient that developed distinct populations with immune escape mutations throughout the course of their infection. Notably, by investigating the co-occurrence of substitutions on individual sequencing reads in the RBD, we found quasispecies harboring mutations that confer resistance to known monoclonal antibodies (mAbs) such as S:E484K and S:E484A. These mutations were acquired without the patient being treated with mAbs nor convalescent sera and without them developing a detectable immune response to the virus. We also provide additional evidence for a viral reservoir based on intra-host phylogenetics, which led to a viral substrain that evolved elsewhere in the patient's body, colonizing their upper respiratory tract (URT). The presence of SARS-CoV-2 viral reservoirs can shed light on protracted infections interspersed with periods where the virus is undetectable, and potential explanations for long-COVID cases

The tree that hides the forest: Cryptic diversity and phylogenetic relationships in the Palaearctic vector Obsoletus/Scoticus Complex (Diptera: Ceratopogonidae) at the European level

Background: Culicoides obsoletus is an abundant and widely distributed Holarctic biting midge species, involved in the transmission of bluetongue virus (BTV) and Schmallenberg virus (SBV) to wild and domestic ruminants. Females of this vector species are often reported jointly with two morphologically very close species, C. scoticus and C. montanus, forming the Obsoletus/Scoticus Complex. Recently, cryptic diversity within C. obsoletus was reported in geographically distant sites. Clear delineation of species and characterization of genetic variability is mandatory to revise their taxonomic status and assess the vector role of each taxonomic entity. Our objectives were to characterize and map the cryptic diversity within the Obsoletus/Scoticus Complex. Methods: Portion of the cox1 mitochondrial gene of 3763 individuals belonging to the Obsoletus/Scoticus Complex was sequenced. Populations from 20 countries along a Palaearctic Mediterranean transect covering Scandinavia to Canary islands (North to South) and Canary islands to Turkey (West to East) were included. Genetic diversity based on cox1 barcoding was supported by 16S rDNA mitochondrial gene sequences and a gene coding for ribosomal 28S rDNA. Species delimitation using a multi-marker methodology was used to revise the current taxonomic scheme of the Obsoletus/Scoticus Complex. Results: Our analysis showed the existence of three phylogenetic clades (C. obsoletus clade O2, C. obsoletus clade dark and one not yet named and identified) within C. obsoletus. These analyses also revealed two intra-specific clades within C. scoticus and raised questions about the taxonomic status of C. montanus. Conclusions: To our knowledge, our study provides the first genetic characterization of the Obsoletus/Scoticus Complex on a large geographical scale and allows a revision of the current taxonomic classification for an important group of vector species of livestock viruses in the Palaearctic region.[Figure not available: See fulltext.

ABO Blood Group and the Risk of Hepatocellular Carcinoma: A Case-Control Study in Patients with Chronic Hepatitis B

BACKGROUND: Studies have observed an association between the ABO blood group and risk of certain malignancies. However, no studies of the association with hepatocellular carcinoma (HCC) risk are available. We conducted this hospital-based case-control study to examine the association with HCC in patients with chronic hepatitis B (CHB). METHODS: From January 2004 to December 2008, a total of 6275 consecutive eligible patients with chronic hepatitis B virus (HBV) infection were recruited. 1105 of them were patients with HBV-related HCC and 5,170 patients were CHB without HCC. Multivariate logistic regression models were used to investigate the association between the ABO blood group and HCC risk. RESULTS: Compared with subjects with blood type O, the adjusted odds ratio (AOR) for the association of those with blood type A and HCC risk was 1.39 [95% confidence interval (CI), 1.05-1.83] after adjusting for age, sex, type 2 diabetes, cirrhosis, hepatitis B e antigen, and HBV DNA. The associations were only statistically significant [AOR (95%CI) = 1.56(1.14-2.13)] for men, for being hepatitis B e antigen positive [AOR (95%CI) = 4.92(2.83-8.57)], for those with cirrhosis [AOR (95%CI), 1.57(1.12-2.20)], and for those with HBV DNA≤10(5)copies/mL [AOR (95%CI), 1.58(1.04-2.42)]. Stratified analysis by sex indicated that compared with those with blood type O, those with blood type B also had a significantly high risk of HCC among men, whereas, those with blood type AB or B had a low risk of HCC among women. CONCLUSIONS: The ABO blood type was associated with the risk of HCC in Chinese patients with CHB. The association was gender-related

Etude de la propagation acoustique dans des milieux stratifiés inhomogènes, application à la caractérisation des fonds marins

With the aim of identifying marine sediments we study the conditions of validity of two homogeneization models giving estimates of the effective velocity in inhomogeneous media. We have considered the Kuster -Toksöz quasi-static model and the Waterman-Truell. dynamic model. Here, we compare the two models experimentally by making measurements on inhomogeneous samples made of glass spheres in gel. We then propose a process for identifying the radius of inclusions and their volume concentration from the measured values of the wave velocity versus frequency, well estimated by the Waterman-Truell model

De la congruence de valeurs à la marque employeur: quelles conséquences pour l'identification et le bouche‐à‐oreille vis‐à‐vis de l'organisation?

International audienceThe war for talent has led organizations to develop a strong employer brand to attract and retain skilled employees. Few studies have examined the antecedents and consequences of the internal employer brand. We focus on the influence of employee‐organization values congruence on the employee's perception of the employer brand and on the influence of the employer brand on organizational identification and positive word‐of‐mouth vis‐à‐vis the employer. Results from a survey of 308 employees show that the employer brand fully mediates the relationship between values congruence and organizational identification and positive word‐of‐mouth. These results have theoretical and managerial implications in terms of employer branding.La guerre des talents pousse les organisations à développer une marque employeur forte afin d'attirer et retenir les salariés compétents. Néanmoins, peu d'études portent sur les antécédents et les conséquences de la marque employeur interne. Cette recherche s'intéresse d'une part, à l'influence de la congruence des valeurs collaborateur‐entreprise sur les perceptions de la marque employeur et d'autre part, à l'influence de celle‐ci sur l'identification organisationnelle et le bouche‐à‐oreille positif vis‐à‐vis de l'employeur. Les résultats de l'enquête menée auprès de 308 salariés montrent que la marque employeur médiatise complètement la relation entre, d'une part, la congruence des valeurs et, d'autre part, l'identification organisationnelle et le bouche‐à‐oreille positif des collaborateurs. Ces résultats ont des implications théoriques et managériales concernant la gestion de la marque employeur

Employer Branding Among Salespeople: An Exploratory Analysis of Glassdoor Reviews

International audienc