A biomechanical model for the analysis of the cervical spine in static postures

To gain a better understanding of the forces working on the cervical spine, a spatial biomechanical computer model was developed. The first part of our research was concerned with the development of a kinematic model to establish the axes of rotation and the mutual position of the head and vertebrae with regard to flexion, extension, lateroflexion and torsion. The next step was the introduction of lines of action of muscle forces and an external load, created by gravity and accelerations in different directions, working on the centre of gravity of the head and possibly a helmet. Although the results of our calculations should be interpreted cautiously in the present stage of our research, some conclusions can be drawn with respect to different head positions. During flexion muscle forces and joint reaction forces increase, except the force between the odontoid and the ligamentum transversum atlantis. This force shows a minimum during moderate flexion. The joint reaction forces on the levels C0-C1, C1-C2, and C7-T1 reach minimum values during extension, each in different stages of extension. Axial rotation less than 35° does not need great muscle forces, axial rotation further than 35° causes muscle forces and joint reaction forces to increase fast. While performing, lateral flexion muscle forces and joint reaction forces must increase rapidly to balance the head. We obtained some indications that the order of magnitude of the calculated forces is correct

Рівняння електромагнітної механіки пористого насиченого середовища

За двоконтинуумного наближення отримано повну систему співвідношень моделі електромагнітомеханіки статистично однорідного та ізотропного пористого насиченого середовища. Враховано наявність подвійного електричного шару в околі межі контакту твердої і рідкої фаз.Complete set of the model equations for electromagnetic mechanics of the porous saturated medium being statistically homogeneous and isotropic is obtained in two-continuum approximation. The presence of a double electrical layer in an environ of contact boundary of solid and liquid phases is taken into account.В двухконтинуумном приближении получено полную систему соотношений модели электромагнитомеханики статистически однородной и изотропной пористой насыщенной среды. Учтено наличие двойного электрического слоя в окрестности границы контакта твердой и жидкой фаз

Change in the distribution of a member of the strand line community: the seaweed fly (Diptera: Coelopidae)

1. Coastal organisms are predicted to be particularly susceptible to the impact of global warming. In this study the distribution and relative abundance of two coastal invertebrates, Coelopa frigida (Fabricius) and C. pilipes are investigated. 2. Coelopa pilipes has a more southerly distribution than C. frigida , and prefers a warmer climate. Coelopa pilipes is less resistant to sub-zero temperatures than C. frigida and its northerly distribution is probably limited by cold winter days. 3. The most recent distribution map of C. frigida and C. pilipes in northern Europe was published a decade ago and showed the northerly extent of the distribution of C. pilipes reaching the north coast of mainland Scotland but its complete absence from the Western and Northern Isles. 4. C. pilipes has now spread throughout the Western Isles and the Orkney Islands but is still absent from Shetland. There has also been an increase in the relative frequency of C. pilipes at sites harbouring coelopids on the British mainland. A similar pattern of distribution change along the west coast of Sweden is reported. 5. It is proposed that these changes have occurred primarily as a result of global warming and in particular due to the recent increase in winter temperatures. A number of other indirect effects may have also contributed to these changes, including a probable change in macroalgae distribution. The implications of these changes for the wrack bed ecosystem and at higher trophic levels are considered

Honeybees balance essential fatty acids and suffer cognitively from deficiency

Abstract Background and aims. Epidemiological data on autoimmune hepatitis (AIH) are scarce. In this study, we determined the clinical and epidemiological characteristics of AIH patients in the Netherlands (16.7 million inhabitants). Methods. Clinical characteristics were collected from 1313 AIH patients (78% females) from 31 centers, including all eight academic centers in the Netherlands. Additional data on ethnicity, family history and symptoms were obtained by the use of a questionnaire. Results. The prevalence of AIH was 18.3 (95% confidential interval [CI]: 17.3-19.4) per 100,000 with an annual incidence of 1.1 (95% CI: 0.5-2) in adults. An incidence peak was found in middle-aged women. At diagnosis, 56% of patients had fibrosis and 12% cirrhosis in liver biopsy. Overall, 1% of patients developed HCC and 3% of patients underwent liver transplantation. Overlap with primary biliary cirrhosis and primary sclerosing cholangitis was found in 9% and 6%, respectively. The clinical course did not differ between Caucasian and non-Caucasian patients. Other autoimmune diseases were found in 26% of patients. Half of the patients reported persistent AIH-related symptoms despite treatment with a median treatment period of 8 years (range 1-44 years). Familial occurrence was reported in three cases. Conclusion. This is the largest epidemiological study of AIH in a geographically defined region and demonstrates that the prevalence of AIH in the Netherlands is uncommon. Although familial occurrence of AIH is extremely rare, our twin data may point towards a genetic predisposition. The high percentage of patients with cirrhosis or fibrosis at diagnosis urges the need of more awareness for AIH

DIMO, a plant dispersal model

Due to human activities many natural habitats have become isolated. As a result the dispersal of many plant species is hampered. Isolated populations may become extinct and have a lower probability to become reestablished in a natural way. Moreover, plant species may be forced to migrate to new areas due to climate change. Species survival in these cases may depend on increasing the connectivity of the landscape by engineering. To investigate and to predict the effects of isolation on the dispersal abilities of plant species, to increase spatial cohesion of a habitat network, to advise policy makers and spatial planners, we developed a simple GIS based dispersal model, DIMO. The model simulates dispersal and establishment of plant populations over a period of time in heterogeneous landscapes on a yearly basis. The model includes proxies for dispersal by wind, animals, water, and self-dispersal. Species establishment is based on habitat suitability maps and simulations include the effect of seed dormancy and generation time. A sensitivity analysis and validation were carried out. The model was validated with Juncus tenuis, an introduced species in the Netherlands. On average the difference between observed and simulated dispersal distance was 9.8 km for a distance of 155 km. The model was applied for a designed corridor in the South of the Netherlands. Model runs indicate that three of the five tested species were able to use the corridor. Two species could not, both due to lack of suitable habitat and one of them also due to lack of dispersal capacity. The results suggest that DIMO is able to evaluate the effectiveness of corridors, but also made clear that besides connectivity the present and future availability of suitable habitats in a corridor is of great importance. The model could be helpful for evaluating policy plans but also for policy making. It may be used for defining and implementation of adaptation measures to climate change on regional to continental scale. Key-words: dispersal, germination, spatial-explicit modeling, climate change, landscape fragmentation, ecological network

Direct-Acting Antiviral Treatment for Hepatitis C Genotypes Uncommon in High-Income Countries: A Dutch Nationwide Cohort Study (vol 8, ofab006, 2021)

Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Donor-specific anti-HLA antibodies are not associated with nonanastomotic biliary strictures but both are independent risk factors for graft loss after liver transplantation

Development and application of statistical models for medical scientific researc