Teak genetic diversity in Ghana shows a narrow base for further breeding and a need for improved international collaboration for provenance exchange.

We evaluated the genetic diversity of teak provenances at a newly established provenance trial with 52 provenances collected from Africa, South America and Asia in Tain II Forest Reserve in Central Ghana. This provenance collection / trial was established to widen the genetic basis for Teak establishment in West Africa. Using Genotyping by Sequencing (GBS) we analysed the genetic diversity of these provenances. Results of the study revealed that, although acquired from a wide geographical range, most Teak provenances in the trial belong to only two distinct groups that are closely related. The implication of this finding is that, for breeding, a wider range of provenances are needed from the original Teak distribution areas and more specifically from Southern India. We conclude that urgent protection of older existing sources of genetic variation in Teak as well as an improvement of international collaboration under the Nagoya protocol with countries with native teak populations is necessary.

Test and Finite Element Analysis of a New Type of Double-Limb Double-Plate Connection Joint in Narrow Base Tower

The connection between the leg members and diagonal members of the urban transmission line tower is mostly in the form of single-limb connection. This paper puts forward a new connection form of pipe double-limb double-plate connection joint, which is based on the model of key joints in an urban narrow base tower structure. The traditional pipe single-limb single-plate and new pipe double-limb double-plate joint are analyzed and studied from three aspects of theory, numerical simulation and experimental study. Through finite element analysis, it is obtained that the section stress of angle steel under eccentric load is 2.05 times of that under axial load, which is basically consistent with the 2.5 times of the theoretical calculation. This shows that the stress of the angle steel in the pipe double-limb double-plate joint is greatly reduced as the axial stress component, which can ensure the safety of the angle steel. Based on the theoretical analysis of the tensile force of two kinds of joints, through the test research and corresponding numerical simulation of pipe single-limb single-plate and pipe double-limb double-plate joints, under the same load, compared with pipe single-limb single-plate joints, the pipe double-limb double-plate joints designed in this paper can greatly reduce the stress of connection plates and members, and compared with the existing joint forms, the bending stress of joint plates can be reduced by about four times, which greatly improves the bearing capacity of the joint. The research on the pipe double-limb double-plate connection joint will provide the basis for the design of new connection joints of narrow base towers in urban areas.

Effects of vestibular stimulation on gait stability and variability

Vestibular information modulates muscle activity during gait, presumably to contribute stability, because noisy electrical vestibular stimulation perturbs gait stability. An important mechanism to stabilize gait in the mediolateral direction is to coordinate foot placement based on a sensory estimate of the trunk center of mass state, to which vestibular information appears to contribute. We, therefore expected that noisy vestibular stimulation would decrease the correlation between foot placement and trunk center of mass state. Moreover, as vestibular modulation of muscle activity during gait depends on step width, we expected stronger effects for narrow-base than normal walking, and smaller effects for wide-base walking. In eleven healthy subjects we measured the kinematics of the trunk (as a proxy of the center of mass), and feet, while they walked on a treadmill in six conditions, including three different step widths: control (preferred step width), narrow-base (steps smaller than hip width), and wide-base (with steps greater than hip width). The three conditions were conducted with and without a bipolar electrical stimulus, applied behind the ears (5 mA). Walking with EVS reduced gait stability but increased the foot placement to center of mass correlation in different step width conditions. The narrow-base walking was the most stable condition and showed a stronger correlation between foot placement and center of mass state. We argue that EVS destabilized gait, but that this was partially compensated for by tightened control over foot placement, which would require successful use of other than vestibular sensory inputs, to estimate center of mass movement.

Design Analysis of 110kV Double Circuit Narrow-Base Steel Pipe Tower

Secondary bending moment and geometric nonlinearity should be taken into account in pipe tower design. Taking the 110kV double-circuit narrow-base steel pipe tower as an example, the 110 kV double-circuit narrow-base steel pipe tower is compared and analyzed through the tower structure design software and the general finite element software ANSYS. The analysis results show that the narrow-base steel tube tower should adopt a rigid-truss structure model, and the influence of the secondary bending moment of the main material and the geometric nonlinearity should be considered. The secondary bending moment effect accounts for about 10-20% of the strength stress of the steel pipe main material. Through comparative analysis, a number of design points are summarized, which provides a certain practical guiding significance for the design and application of the double-circuit narrow-base steel pipe tower.

Composite materials made narrow base 110 kV overhead suspension tower for the port terminals approach

В работе представлена разработка промежуточной опоры для ультракомпактных ВЛ 110 кВ. Технические решения приводятся на примере реконструкции конкретного объекта – ВЛ 110 кВ. Работа выполнена в соответствии с «Техническим заданием на разработку специальных технических условий с использованием провода с защитной изоляцией для воздушных линий электропередачи на напряжение 110 кВ марки СИП-7 с целью уменьшения охранной зоны ВЛ». Выполнен анализ характеристик существующих промежуточных опор типа ПБ 110-4 и промежуточной опоры ВЛ 110 кВ с применением защищённого провода СИП-7. Выбран тип провода для проведения реконструкции линии. Осуществлён расчёт нагрузок на промежуточную опору из композитных материалов типа ПК 110-2 ПЗИ с учётом требований существующей нормативной базы, механический расчёт промежуточной композитной опоры, учитывающий различные климатические воздействия на провода и изоляторы. Предложены конструктивные элементы обеспечения заземления металлических частей опор из композитных материалов и элементы крепления самонесущих изолированных проводов к траверсам композитной опоры. This paper presents the development of suspension tower for ultra-compact 110 kV overhead lines. Technical solutions performed are based on example of reconstruction of 110 kV overhead line. The research aimed to reduce the security zone of overhead lines by using СИП-7 insulation type cable. The analysis of the characteristics of the existing suspension towers of the ПБ 110-4 type and 110 kV overhead line tower with the use of protected wire SIP-7 is carried out. Authors made the calculation of the loads on the suspension tower made of composite materials of the ПК 110-2 ПЗИ type, taking into account the requirements of the existing regulatory framework, they also carried out the mechanical calculation of the tower, considering various climatic effects on the wires and insulators. Structural elements of providing grounding of metal parts of tower made of composite materials and fastening elements of self-supporting insulated wires to the cross-arms of a tower are proposed.

THE EFFECTS OF AGE-BASED EVALUATIONS ON OLDER ADULTS’ GAIT VARIABILITY

Older adults are stereotyped as being slow, weak, and frail. In this study we examined how these stereotypes about age-related physical decline affect older adults’ walking performance. Healthy, community-dwelling older adults were asked to walk at their own comfortable pace along a 24’ temporospatial-measuring walkway 10 times. For some participants this was done with a normal-base of support (i.e., usual gait). However, for other participants this was done with a narrow-base of support (i.e., walking within a path of 15 cm outlined by tape). Walking tasks were done either in the presence or absence of a negative age-based evaluation. Results showed that the negative age-based evaluations were associated with greater stride-to-stride variability, particularly for participants who felt less confident in their abilities. Given that gait variability is a predictor of falling, this raises the possibility that negative age-based evaluations can produce concerns that are an intrinsic risk factor for falls.

Mimicking T- shaped giant meckel's diverticulum: another rare anatomical variant complicating small bowel obstruction by adhesions

We report case with Meckel's diverticulitis complicated by adhesive intestinal obstruction. An adolescent of 13-yr-old boy with history of recurrent right sided lower abdominal pain and vomiting for two days. According to his mother he had been suffering this type of pain intermittently for last three years which was treated conservatively. This time the pain was out of proportion therefore she reported in tertiary hospital. On examination patient was tender at right iliac fossa region with abdominal guarding. CT scan of abdomen revealed multiple fluid-filled, dilated proximal bowel loops. Meckel's diverticulum was not suspected until diagnostic laparoscopy was performed. Patient was converted to open laparotomy where the giant (13 cm sized), narrow base mimicking T-shaped Meckel’s diverticulum and inter bowel loop adhesions near terminal ileum were seen. About 20 cm affected ileal segment with Meckel’s diverticulum resected and primary end to end anastomosis performed. The postoperative course remained uneventful. Histopathology report confirms the inflammation of Meckel’s diverticulum. Significance of this type of Meckel’s diverticulum is its T-shaped mimicking appearance with giant size body and narrow base and was manifested with recurrent sub occlusive intestinal obstruction in the period of three years. It is the second ever reported case in English journals.