783 research outputs found
Biomechanical Computer Models
In the past decade computer models have become very popular in the field of biomechanics due to exponentially increasing computer power. Biomechanical computer models can roughly be subdivided into two groups: multi-body models and numerical models. The theoretical aspects of both modelling strategies will be introduced. However, the focus of this chapter lies on demonstrating the power and versatility of computer models in the field of biomechanics by presenting sophisticated finite element models of human body parts. Special attention is paid to explain the setup of individual models using medical scan data. In order to reach the goal of individualising the model a chain of tools including medical imaging, image acquisition and processing, mesh generation, material modelling and finite element simulation –possibly on parallel computer architectures- becomes necessary. The basic concepts of these tools are described and application results are presented. The chapter ends with a short outlook into the future of computer biomechanics
Cosmic ray records in Antarctic meteorites
The cosmogenic radionuclides Be(10), Al(26), and Mn(53) and noble gases were determined in more than 28 meteorites from Antarctica by nuclear analytical techniques and static mass spectrometry, respectively. The summarized results are listed. The concentrations of Al(26) and Mn(53) are normalized to the repective main target elements and given in dpm/kg Si sub eq and dpm/kg Fe. The errors stated include statistical as well as systematical errors. For noble gas concentrations estimated errors are 5% and for isotopic ratios 1.5%. Cosmic ray exposure ages T sub 21 were calculated by the noble gas concentrations and the terrestrial residence time (T) on the basis of the spallogenic nuclide Al(26). The suggested pairing of the LL6 chondrite RKPA 80238 and RKPA 80248 and the eucrites ALHA 76005 and ALHA 79017 is confirmed not only by the noble gas data but also by the concentrations of the spallation produced radionuclides. Futhermore, ALHA 80122, clasified as an H6 chondrite, has a noble gas pattern which suggest that this meteorite belongs to the ALHA 80111 shower
The support for farmer-led seed systems in African seed laws.
The synthesis report is part of a series of papers on Integrated Seed Sector Development (ISSD) in Africa’s thematic working group on Matching national realities with global commitments. The thematic working group addressed the main question on how African governments implement their global commitments while fostering a viable pluralistic sector. The main hypothesis was that making these commitments more coherent with the practices and realities of farmers and creating an enabling environment for strengthening multiple seed systems will increase farmers’ access to quality seed. Three main topics were discussed under this theme: access and benefit sharing for climate resilient seed systems; national and regional seed laws that support the development of a robust, integrated seed sector that supports smallholder farmers' needs; and creating room for informal and intermediary seed systems in a UPOV '91 informed Plant Variety Protection system.
The study was conducted to answer a key question on how the various national and regional seed laws relate to the diversity of seed systems that exist in a given country. More specifically how current seed laws affect informal (farmer-based) seed systems and in what manner seed laws can be adapted to support these seed systems. Policies, laws and regulations of 32 African countries were carefully reviewed to identify some best practices and key issues and challenges in regulation. Findings from the study indicate that the main challenge for many African countries is that their seed regulations don’t include provisions that support farmer -led seed systems. As a way forward, there is need for revision of existing regulatory frameworks to takes into account the needs and characteristics of the various seed systems in order to increase the availability of quality seed of preferred varieties for all farmers
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CU Boulder Students' Sense of Community on Social Media
The purpose of this study is to examine college students’ sense of community on social media. I collected data by surveying 74 respondents who are at least 18 years old and are currently enrolled as students (undergraduate or graduate) at the University of Colorado Boulder. The survey questions assess the extent of participants’ community ties. In the results of my research study, 64% of participants found communities through social media and 57% reported having a better sense of community while using social media. Most respondents agreed that social media is beneficial for advocacy groups and professional networking, but not many used social media for these purposes. Most respondents with marginalized identities considered social media useful for affirming their identities and networking with others who share those identities. Identity affirmation, networking, and activism are potential social media benefits for marginalized communities. Professional networking and engaging with advocacy communities/organizations are potential areas for students to expand their community ties on social media. The social media advantages of marginalized identity affirmation and the ability to find various communities on social media foster community building, whereas the social media disadvantages of shallow connections and inhibiting social interactions hinder community building among college students.</p
Cosmogenic rare gases and 10-Be in a cross section of Knyahinya
The concentrations of cosmogenic nuclides were studied as a function of shielding on samples from a cross section of the 293 kg main fragment of the L5 chondrite Knyahinya. The stone broke into two nearly symmetrical parts upon its fall in 1866. The planar cross section has diameters between 40 and 55 cm. He, Ne, and Ar were measured on about 20 samples by mass spectrometry and the 10-Be activities on aliquots of 10 selected samples were determined by AMS. The 10-Be data are presented and the abundances of spallogenic nuclides are compared with the model calculations reported by Reedy for spherical L chondrites. The 10-Be production rates in Knyahinya are shown versus the shielding parameter 22-Ne/21-Ne
Determination of Gross Sections for the Production of 7Be, 10Be and 22Na by High-Energy Protons
Determination of the Specific Activities of the Cosmogenic Nuclides 10Be and 26Al in Meteorites from the Sahara by Means of Accelerator Mass Spectrometry
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