Bayesian methods in clinical trials with applications to medical devices

Campbell, Gregory The Korean Statistical Society 2017 Communications for statistical applications and me Vol.24 No.6

Bayesian statistics can play a key role in the design and analysis of clinical trials and this has been demonstrated for medical device trials. By 1995 Bayesian statistics had been well developed and the revolution in computing powers and Markov chain Monte Carlo development made calculation of posterior distributions within computational reach. The Food and Drug Administration (FDA) initiative of Bayesian statistics in medical device clinical trials, which began almost 20 years ago, is reviewed in detail along with some of the key decisions that were made along the way. Both Bayesian hierarchical modeling using data from previous studies and Bayesian adaptive designs, usually with a non-informative prior, are discussed. The leveraging of prior study data has been accomplished through Bayesian hierarchical modeling. An enormous advantage of Bayesian adaptive designs is achieved when it is accompanied by modeling of the primary endpoint to produce the predictive posterior distribution. Simulations are crucial to providing the operating characteristics of the Bayesian design, especially for a complex adaptive design. The 2010 FDA Bayesian guidance for medical device trials addressed both approaches as well as exchangeability, Type I error, and sample size. Treatment response adaptive randomization using the famous extracorporeal membrane oxygenation example is discussed. An interesting real example of a Bayesian analysis using a failed trial with an interesting subgroup as prior information is presented. The implications of the likelihood principle are considered. A recent exciting area using Bayesian hierarchical modeling has been the pediatric extrapolation using adult data in clinical trials. Historical control information from previous trials is an underused area that lends itself easily to Bayesian methods. The future including recent trends, decision theoretic trials, Bayesian benefit-risk, virtual patients, and the appalling lack of penetration of Bayesian clinical trials in the medical literature are discussed.

THE FIBONACCI LENGTH OF CERTAIN CENTRO-POLYHEDRAL GROUPS

CAMPBELL, C. M.,CAMPBELL, P. P. 한국전산응용수학회 2005 Journal of applied mathematics & informatics Vol.19 No.1

We examine the Fibonacci length of certain centro-polyhedral groups and show that in some cases the lengths depend on tribonacci sequences. Further we obtain specific examples of infinite families of three-generator groups with constant, linear and (3-step) Wall number dependent Fibonacci lengths.

A Bone in the Throat : The Taiwan Straits Issue and Sino-American Relations in the Post-Cold War Era

Campbell, Joel R. 경희대학교 아태지역연구원 1998 아태연구 Vol.5 No.-

Keeping the Bugs out of Beer without Pesticides

Campbell Colin 한국응용곤충학회 2004 한국응용곤충학회 학술대회논문집 Vol.2004 No.1

Economic Conditions and Male First Marriage in Northeast China, 1749-1909

Campbell, Cameron,Lee, James 성균관대학교 동아시아학술원 2008 Sungkyun Journal of East Asian Studies Vol.8 No.1

This paper shows that economic conditions, as reflected in grain prices, helped determine rates of bachelorhood in northeast China from 1749 to 1909. For many rural populations, high grain prices are a useful measure of economic conditions because they typically indicate a poor harvest, leading to increased economic pressure and reduced consumption. Our analysis of 30,000 unmarried adult mates in rural Liaodong from 1749-1909 indicate that while current grain prices did not affect marriage chances, prior grain prices twenty years previous did: boys born when grain prices were high were more likely to never marry than boys born under normal conditions. Results are consistent with an explanation in which increased incidence of female neglect or possibly infanticide when times were bad led to worsened sex imbalances in the marriage market two decades later.

HIGH EFFICIENCY, BACK-CONTACT BIFACIAL SOLAR CELLS AND APPLICATION

Campbell, Matthew P.,DeCeuster, Denis M.,Cousins, Peter,Detrick, Adam,Manalo, Raphael,Mulligan, William P. 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.05

SunPower's corporate mission is to reduce the installed cost of solar electricity 50% by 2012. As part of that mission, the company is continually exploring novel technologies that might enable progress towards the goal. This paper describes SunPower's efforts to decrease the levelized cost of electricity for solar power plants through the use of bifacial cell and system technology. The results of the first production run of SunPower bifacial cells and modules are presented. Future bifacial system development plans are reviewed.

CANADIAN NUCLEAR EXPORT POLICY TOWARD DEVELOPING COUNTRIES

Campbell, Ross The Institute for Far Eastern Studies Kyungnam Uni 1979 ASIAN PERSPECTIVE Vol.3 No.1

It is a pleasure for me to participate in this conference and to have the opportunity of exchanging views on the conference theme "Prospects for Nuclear Weapons Proliferation in Developing Countries". The Institute for Far Eastern Studies is to be congratulated on its choice of topic and its timing. Your timing is excellent because your conference comes at the midway point of the International Nucleal' Fuel Cycle Evaluation program(INFCE) and enables us all to focus on the work that has yet to be done and the directions in which tile second half of INFCE should be moving. I should like to return to this matter at the end of my talk as I have some thoughts that I would like to leave with you, Your conference theme, concentrating as it does ell nuclear issues as they affect developing countries, appeals to ole for two main reasons. First, because I believe the discussions here will confirm that among the non-nuclear-weapon-States, parties to the Treaty on tile Non-proliferation of Nuclear Weapons or otherwise, it will be the continuing judgment that non-proliferation of nuclear weapons is an objective so compelling for all governments that it will not be sacrificed on the altar of military adventurism. This applies equally to governments whose regional security problems might make a weapons program appear attractive. In today's climate regarding proliferation, the penalties would be just too great.

SOME PROBLEMS IN GROUP PRESENTATIONS

CAMPBELL, COLIN M.,ROBERTSON, EDMUND F. Korean Mathematical Society 1982 대한수학회지 Vol.19 No.2

Dendro-dendritic bundling and shared synapses between gonadotropin-releasing hormone neurons.

Campbell, Rebecca E,Gaidamaka, Galina,Han, Seong-Kyu,Herbison, Allan E National Academy of Sciences 2009 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.106 No.26

<P>The pulsatile release of gonadotropin-releasing hormone (GnRH) is critical for mammalian fertility, but the mechanisms underlying the synchronization of GnRH neurons are unknown. In the present study, the full extent of the GnRH neuron dendritic tree was visualized by patching and filling individual GnRH neurons with biocytin in acute brain slices from adult GnRH-green fluorescent protein (GFP) transgenic mice. Confocal analysis of 42 filled GnRH neurons from male and female adult mice revealed that the dendrites of the great majority of GnRH neurons (86%) formed multiple close appositions with dendrites of other GnRH neurons. Two types of interactions were encountered; the predominant interaction was one of vertical dendritic bundling where dendrites were found to wrap around each other in the same axis. The other interaction was one in which a GnRH neuron dendrite intercepted other GnRH neuron dendrites in a perpendicular fashion. Electron microscopy using pre-embedded, silver-enhanced immunogold labeling for both GnRH and GFP peptides in GnRH-GFP transgenic mice, confirmed that GnRH neuron dendrites were often immediately juxtaposed. Membrane specializations, including punctae and zonula adherens, were found connecting adjacent dendritic elements of GnRH neurons. Remarkably, individual afferent axon terminals were found to synapse with multiple GnRH neuron dendrites at sites of bundling. Together, these data demonstrate that GnRH neurons are not isolated from one another but, rather, interconnected via their long dendritic extensions. The observation of shared synaptic input to bundled GnRH neuron dendrites suggests a mechanism of GnRH neuron synchronization.</P>

Field measurements of natural periods of vibration and structural damping of wind-excited tall residential buildings

Campbell, S.,Kwok, K.C.S.,Hitchcock, P.A.,Tse, K.T.,Leung, H.Y. Techno-Press 2007 Wind and Structures, An International Journal (WAS Vol.10 No.5

Field measurements of the wind-induced response of two residential reinforced concrete buildings, among the tallest in the world, have been performed during two typhoons. Natural periods and damping values have been determined and compared with other field measurements and empirical predictors. Suitable and common empirical predictors of natural period and structural damping have been obtained that describe the trend of tall, reinforced concrete buildings whose structural vibrations have been measured in the collection of studies in Hong Kong compiled by the authors. This data is especially important as the amount of information known about the dynamic parameters of buildings of these heights is limited. Effects of the variation of the natural period and damping values on the alongwind response of a tall building for serviceability-level wind conditions have been profiled using the gust response factor approach. When using this approach on these two buildings, the often overestimated natural periods and structural damping values suggested by empirical predictors tended to offset each other. Gust response factors calculated using the natural periods and structural damping values measured in the field were smaller than if calculated using design-stage values.