Laboratory-scale investigation of response characteristics of liquid-filled rock joints with different joint inclinations under dynamic loading

In underground rock engineering,water-bearing faults may be subjected to dynamic loading,resulting in the coupling of hydraulic and dynamic hazards.Understanding the interaction mechanism between the stress waves induced by dynamic loadings and liquid-filled rock joints is therefore crucial.In this study,an auxiliary device for simulating the liquid-filled layer was developed to analyze the dynamic response characteristics of liquid-filled rock joints in laboratory.Granite and polymethyl methacrylate(PMMA)specimens were chosen for testing,and high-amplitude shock waves induced by a split Hopkinson pressure bar(SHPB)were used to produce dynamic loadings.Impact loading tests were conducted on liquid-filled rock joints with different joint inclinations.The energy propagation coefficient and peak liquid pressure were proposed to investigate the energy propagation and attenuation of waves propagating across the joints,as well as the dynamic response characteristics of the liquid in the liquid-filled rock joints.For the inclination angle range considered herein,the experimental results showed that the energy propagation coefficient gently diminished with increasing joint inclination,and smaller coefficient values were obtained for granite specimens compared with PMMA specimens.The peak liquid pressure exhibited a gradually decreasing trend with increasing joint inclination,and the peak pressure for granite specimens was slightly higher than that for PMMA specimens.Overall,this paper may provide a considerably better method for studying liquid-filled rock joints at the laboratory scale,and serves as a guide for interpreting the underlying mechanisms for interactions between stress waves and liquid-filled rock joints.

A LABORATORY INVESTIGATION OF CHARACTERISTICS OF TORNADO-LIKE VORTICES OVER VARIOUS ROUGH SURFACES

In this paper,the effects of surface roughness on tornado-like vortices are studied in the laboratory for simulating tornado vortex at the Disaster Prevention Research Institute,Kyoto University,Japan. In the experiments,the distribution of the horizontal wind speed and direction at five different heights were measured with a hot-wire anemometer and a mini-vane.The characteristics of wind speed and direc- tion distribution for the tornado vortex on the various rough surfaces were first revealed with the simulative method in laboratory.By changing the swirl ratio(S=tanθ/2a)of simulation device,it is found that,the size of tornado-like vortex core will become almost identical,as the swirl ratio S exceeds a certain value (S>1.5). The experimental results can be used not only to explain the observed facts in the atmosphere but also to provide the experimental bases for some theoretical studies.

Clinical/Behavioral Monitoring of Rodents and Rabbits Undergoing Scientific Experiments

Background: We currently have international and national guidelines regarding the assessment and monitoring of clinical signs and humane endpoints in animals used in teaching and research, which make the performance of these activities mandatory for any experiment and professional working in this area. Assigning the severity of a research experiment is the result of an analysis of records of observations of the animal’s behavior, and clinical signs. The aim of this study was to describe the importance of carrying out a severity assessment associated with clinical and behavioral monitoring of rodents and rabbits during experimentation to maintain the welfare of these animals undergoing scientific research. Methods: The literature search was carried out using the following terms: “Monitoring”;“Humane endpoints”;“Animal welfare”, “Rodents”;“Rabbits”, and as connectors “and”;“or”, in the following databases: PubMed;LILACS/BIREME and SciELO. Results: A total of 987 articles were identified in the databases, and 20 of these studies were included in this review. Conclusions: Humane endpoint protocols and procedure severity tables are of the utmost importance, both from an ethical point and to refine the results of research conducted on laboratory animals. They should be drawn up jointly by the teams responsible for the project and the maintenance of the animals during the research period, and the data obtained should be published so that the scientific community can have access to it, helping to disseminate these practices, as well as helping to draw up new procedures. Monitoring and evaluating the welfare and clinical condition of animals undergoing scientific research procedures is the responsibility of the professors, researchers, veterinarians, and animal facility coordinators. The Ethics Committee on the Use of Animals must monitor all the activities conducted with the animals, by inspecting the experimental procedures and the physical environment of the laboratory animal facility where the animals are housed.

A Retrospective Study of the Prevalence of Female Infertility in the Southwest Region, Cameroon

Background: Infertility is a major reproductive health care problem that affects the wellbeing of women. Although views vary between cultures, infertility is seen almost exclusively as a woman’s problem in Africa with secondary infertility being the most prevalent while sexually transmitted infections the most investigated cause of infertility. Objective: The aim of this study was to determine the prevalence of female infertility in the Limbe and Buea Regional hospitals of the Southwest region of Cameroon from 2015-2019. Materials and Methods: A retrospective descriptive design was used which involved studying clinical files of women within the reproductive age group (15 - 49) with infertility problems, at the gynaecological and maternity units of the selected hospitals in the Southwest region of Cameroon over a period of five years (2015-2019). Data were collected from all files included in the study. Results: A total of 4609 females visited the two hospitals for investigation and 1111 files were identified with infertility giving prevalence of 24 %. Three hundred and forty-three (343;31%) presented with primary infertility while seven hundred and sixty-eight (768;69%) had secondary infertility. The average age of affected female was 31.5 making age the predisposing factor of infertility because after the peak of 25 years, infertility started decreasing. Employment with salary and the association between diagnosis and age had a p-value < 0.005 which was considered significant in this study. Conclusion: This study found that the prevalence of infertility in Southwest Cameroon is high with secondary infertility being most predominant among infertile women with a prevalence of 69% caused principally by sexually transmitted infection (STIs). Age and occupation were significantly associated with infertility. Routine laboratory screening of women of reproductive age may reduce the high prevalence of infertility in the study area.