Historical Development of the Linear Nonthreshold Dose-Response Model as Applied to Radiation

[Excerpt] Despite the nearly universal adoption of the linear nonthreshold dose response model (LNT) as the primary basis for radiation protection standards for the past half century, the LNT remains highly controversial and a contentious topic of discussion among health physicists, radiation biologists, and other radiological scientists. Indeed, it has been pointed out that the LNT has assumed the status of a paradigm, synonymous with an ideal, standard, or paragon or perhaps to some, a sacred cow. Reduced to its very basics, the LNT postulates that every increment of ionizing radiation dose, however small, carries with it a commensurate increase in the chance or risk that the exposed individual will suffer some undesirable radiation effect, and that the risk thus incurred is directly proportional or linearly related to the dose. The specific effects are termed “stochastic,” which has been defined as “of a random or statistical nature.” Stochastic or probabilistic effects of radiation may occur as a result of low doses and are generally taken to be cancers (including leukemias) and genetic defects in the progeny. The severity of these radiation-induced stochastic effects, should they occur, are independent of the dose that produced them; thus, even though the likelihood or probability of an occurrence may be small to negligible, any and all manifestations of a radiation induced stochastic effect will have equal severity. By contrast, higher doses of radiation are known to produce characteristic somatic or deterministic effects including erythema, epilation, sterility, diminution of blood cell counts, cataracts and, in very high exposures, acute and chronic radiation syndromes. Such frank biological effects are nonstochastic in nature (in fact, they were at one time termed “nonstochastic effects”) and will always be manifested once a particular minimum dose – i.e., a “threshold” – has been received. The severity of the effect is related to the dose. Below the threshold dose there will be no demonstrable effect; as the dose increases beyond the threshold, so does the severity of the effect, or the degree of harm. … The purpose of the above discussion is to illustrate the underlying controversy and confusion that surrounds the LNT today, as well to underscore the lack of precision that sometimes accompanies the arguments of both the proponents and opponents of the LNT. Given that the LNT is a low dose phenomenon, there needs to at least be consensus on what is low dose, and such a consensus needs also to include consideration of other relevant and important factors such as the dose rate and specific stochastic end point (i.e., type of cancer or mutation). With this as a backdrop, the historical development and gyrations that led to the LNT as it is currently applied (or, some would say, misapplied) in radiological protection can be examined in the context of current scientific thinking with respect to radiation effects. It is not the purpose of this paper to endorse any particular position or to take sides but rather to present the story in a factual and fair minded manner. Hopefully, what follows will successfully achieve this goal. Thus, this paper will briefly review the scientific bases and supporting studies that led to the development and acceptance of the LNT in health physics. It will briefly touch on such topics as hormesis and other studies, such as the classic work of the late Robley Evans, that clearly demonstrate a threshold and nonlinear response for certain stochastic effects such as osteogenic sarcoma, along with the plethora of studies that suggest or have been interpreted to indicate that for at least some end points (i.e., cancers), response to ionizing radiation is consistent with the LNT model

The Aesthetic Which is Not One: The Feminist (un)Aesthetic in the Works of Caryl Churchill and Suzan Lori-Parks

In the following essay I will establish a theatrical feminist (un)aesthetic that resists essentialism, which creates the dramaturgical space necessary to present a feminist (un)subject. The rejection of Ibsenite realism within the (un)aesthetic disrupts the male gaze as theorized by Laura Mulvey. This is achieved through a materialist feminist focus that highlights the constructive nature of gender difference anf disrupts the production of woman as sign. Through the use of Brechtian alienation techniques and theatrical formalism, the playwrights Caryl Churchill (Cloud Nine) and Suzan-Lori Parks (Venus) force the feminist goals of the (un)aesthetic to be considered beyond the context of the theatrical event. I will demonstrate that both Churchill and Parks successfully present an (un)subject in becoming, that is based on a representational economy of refusal. By refusing traditional subject formation both playwrights are able to trouble and destabilize the patriarchal metanarrative of feminine subjectivity within theatrical representation

The role of community college-based transfer programming in transfer student success.

More students now begin their postsecondary education at the two-year college level with the intention of transferring to earn a bachelor\u27s degree, making the transfer function more important. Recent government mandates in Kentucky brought about new programming efforts to aid student transitions between public institutions. This study was designed to determine whether the University of Louisville (ULtra) Transfer Program, designed as a bridge between Jefferson Community and Technical College and the University of Louisville (UofL), played a significant role in community college students\u27 successful academic transition to the four-year institution. Participants of this study were 227 community college students who transferred to UofL between 2006 and 2011. Results indicated that, even when controlling for relevant background characteristics (age, high school GPA, and ACT score), students who participated in the Ultra program had more credit hours earned and accepted toward their major, suffered less transfer shock after the transition to UofL, earned a slightly higher first and significantly higher second semester GPA, and had a higher persistence rate at UofL

On Being A Good Neighbor

This research supports the design of a museum dedicated to reconciliation on the issue of human slavery. Throughout the museum guests will be ushered through contemplation to prepare for the context of the museum, gallery exhibitions chronicling the slavery and corporate apologia. The aim of the museum is to aid guests toward taking ownership of the history of slavery while simultaneously offering up forgiveness for it. Platforms for spoken word art, lecture halls and spaces dedicated to dialogue will be included. The chronological progression through the museum will move guests from introspection to education, personal acceptance to forgiveness. Guests will end the museum at a community space, reconciled to each other and on equal ground

No more worksheets: a pre-service teacher\u27s look at manipulatives

The purpose of this study is to explore the use of manipulatives during math. This is done by examining manipulatives in reference to student interest, diverse learners, student response, and student opinions. The study was conducted in an elementary school in the Winslow Township school district located in the Camden County region of South Jersey. All seventeen participants were taken from a collaboratively taught first grade classroom. Collection of data was done through the use of video tape, student journals, tests and my personal observations. Data was triangulated through the examination of multi-sources (video, journals, tests, observations), and themes, scores and interesting remarks were analyzed. In conclusion to the study one unifying pattern that was found during the exploration of manipulatives was student eagerness. Their eagerness to use and explore manipulatives provided them with the openness to learn thus increasing their knowledge of the subject at hand

Social life and ritual practices in an Alaskan Pentecostal community (The First Assembly of God, Fairbanks)

Thesis (M.A.) University of Alaska Fairbanks, 2013This MA thesis research project focuses on the First Assembly of God Church in Fairbanks, Alaska. It seeks to better understand the implementation of Pentecostal-Charismatic (PC) Christianity in 21st century urban Alaska. While social activism and outreach form a significant portion of the success of Pentecostalism in Alaska (as anywhere else), my research shows that it is also substantially due to the appeal of ritual to newcomers. In particular, I suggest that there are forms of spiritual possession and spirit embodiment that need to be examined in relation to the attractiveness of Pentecostalism in Fairbanks. There is a gap in academic literature pertaining to Pentecostal rituals. Recent anthropological studies have focused primarily on notions of conversion, rupture, empowerment, and modernization. My research complements these studies by shedding an unprecedented light on Pentecostal processes of ritualization. Participant observation and interviews were used to examine ritual activity and the nature of spiritual gifts within PC Christianity in Fairbanks.Chapter 1. Introduction -- Chapter 2. Theoretical framework -- 2.1. Spiritual possession: The divide between possession theorists -- 2.2. Ritual -- 2.3. Mobility (fluidity) -- Chapter 3. Background -- 3.1. Christianity in Alaska -- 3.2. Brief history of Pentecostalism -- 3.3. Assembly of God Church (AG) -- 3.3.1. First Assemblies in Alaska -- Chapter 4. The culture of Pentecostalism -- 4.1. Connection between churches -- 4.2. Membership -- 4.3. Mobility and church planting -- Chapter 5. An ethnographer in the assembly -- 5.1. Participant observation in a PC community -- 5.2. Interviews and conversations with faith practitioners -- Chapter 6. Rituals and ritualized social programs in the assembly -- 6.1. Wednesday night Bible study -- 6.2. Tuesday night Bible study (women's 'Bible study) -- 6.3. Retreats -- 6.3.1. Men's retreat -- 6.3.2. Women's retreat -- 6.4. Handprint -- 6.5. Quilting circle -- 6.6. Sunday service -- 6.6.1. Usual service -- 6.6.2. Special Sunday services -- Chapter 7. Discussion of key themes -- 7.1. Socio-political themes in the assembly -- 7.2. Language versus physicality in rituals -- 7.3. Reassessing the shamanism/possession divide -- Chapter 8. Conclusion -- References cited

An investigation of institutional arrangements for design and delivery of multimodal public transport in Melbourne

Intermodal service coordination designed to achieve a „seamless network‟ is a common feature of high-quality public transport systems. This paper explores the intention and the reality of the institutional arrangements that govern the coordination of bus, tram and train services in Melbourne under the franchise agreements.State Government policies and contractual obligations set out the intended lines of responsibility for the planning of transport networks in relation to design and delivery of coordinated multimodal services. Interviews, designed to examine the practical application of these policies and obligations, were conducted during 2009 with staff from the Department of Transport, the private operators, the Bus Association and from Metlink – the company established to improve communication and coordination of public transport services.The results of this investigation highlight the significant differences between actual practices and the stated intentions of both government policies and existing contracts with private sector organisations.The lack of effective designation of responsibilities, ineffective communication at many levels across numerous institutions, and an absence of skilled staff will continue to impede the development of a cohesive transport network in Melbourne. These problems were not addressed in the design of the new franchise agreements that began in December 2009

United States Transuranium and Uranium Registries

The United States Transuranium and Uranium Registries are unique human tissue research programs studying the distribution, dose, and possible biological effects of the actinide elements in man, with the primary goal of assuring the adequacy of radiation protection standards for these radionuclides. The Registries research is based on radiochemical analysis of tissues collected at autopsy from voluntary donors who have documented occupational exposure to the actinides. To date, tissues, or in some cases radioanalytical results only, have been obtained from approximately 300 individuals; another 464 living individuals have volunteered to participate in the Registries research programs and have signed premortem informed consent and autopsy permissions. The Registries originated at the National Plutonium Registry which was started in 1968 as a then Atomic Energy Commission project under the aegis of a prime contractor at the Hanford site. In 1970, the name was changed to the United States Transuranium Registry to reflect a broader involvement with the higher actinides. In 1978, an administratively separate parallel registry, the United States Uranium Registry, was formed to carry out similar studies among uranium fuel cycle workers

United States Transuranium and Uranium Registries. Annual Report, October 1, 1993--September 30, 1994

This report summarizes the salient activities and progress of the United States Transuranium. and Uranium Registries for the period October 1, 1993 through September 30, 1994, along with details of specific programs areas including the National Human Radiobiology Tissue Repository (NHRTR) and tissue radiochemistry analysis project. Responsibility for tissue radioanalysis was transferred from Los Alamos National Laboratory to Washington State University in February 1994. The University of Washington was selected as the Quality Assurance/Quality Control laboratory and a three way intercomparison with them and LANL has been initiated. The results of the initial alpha spectrometry intercomparison showed excellent agreement among the laboratories and are documented in full in the Appendices to the report. The NHRTR serves as the initial point of receipt for samples received from participants in the USTUR program. Samples are weighed, divided, and reweighed, and a portion retained by the NHRTR as backup or for use in other studies. Tissue specimens retained in the NHRTR are maintained frozen at -70 C and include not only those from USTUR registrants but also those from the radium dial painter and thorium worker studies formerly conducted by Argonne National Laboratory. In addition, there are fixed tissues and a large collection of histopathology slides from all the studies, plus about 20,000 individual solutions derived from donated tissues. These tissues and tissue related materials are made available to other investigators for legitimate research purposes. Ratios of the concentration of actinides in various tissues have been used to evaluate the biokinetics, and retention half times of plutonium and americium. Retention half times for plutonium in various soft tissues range from 10-20 y except for the testes for which a retention half time of 58 y was observed. For americium, the retention half time in various soft tissues studied was 2.2-3.5 y