ACTIVE LEARNING AND OPTIMAL CLIMATE POLICY

( In Chang Hwang ),( Richard S. J. Tol ),( Marjan W. Hofkes ) 한국환경경제학회·한국자원경제학회(구 한국환경경제학회) 2015 한국환경경제학회 학술발표논문집 Vol.2015 No.하계

This paper develops a climate-economy model with uncertainty, irreversibility and active learning. Whereas previous papers assume passive learning from one observation per period, or experiment with control variables to gain additional information, this paper considers active learning from research investment in improved observations. We restrict ourselves to improving observations of the global mean temperature. We find that the decision maker invests a significant amount of money in climate research, far more than the current level, in order to increase the rate of learning about climate change. This helps the decision maker take improved decisions. The level of uncertainty decreases more rapidly in the active learning model with research investment than in the passive learning model only with temperature observations. As a result, active learning reduces the optimal carbon tax. The greater the risk, the larger is the effect of learning. The method proposed here is applicable to any dynamic control problem where the quality of monitoring is a choice variable.

Tail-effect and the role of greenhouse gas emissions control

( In Chang Hwang ),( Richard S. J. Tol ),( Marjan W. Hofkes ) 한국환경경제학회·한국자원경제학회(구 한국환경경제학회) 2014 한국환경경제학회 학술발표논문집 Vol.2014 No.하계

This paper investigates the role of emissions control on reducing the effect of fat-tailed uncertainty about climate change. Through a simple analysis on temperature distributions and some numerical simulations using the well-known Dynamic Integrated model of Climate and the Economy (DICE model), we find that the option for emissions control effectively prevents the tail-effect. Climate policy based on hyperbolic absolute risk aversion (HARA) utility is less sensitive to fat tails than climate policy based on constant relative risk aversion (CRRA) utility.

Diurnal variation of default mode network in patients with restless legs syndrome

Ku, Jeonghun,Lee, Yeong Seon,Chang, Hyuk Won,Earley, Christopher J.,Allen, Richard P.,Cho, Yong Won Elsevier 2018 SLEEP MEDICINE Vol.41 No.-

<P><B>Abstract</B></P> <P><B>Objective</B></P> <P>Restless legs syndrome (RLS) patients compared to controls have been found to have abnormal patterns in the default mode network (DMN) in the morning when symptom threshold is the highest and symptoms are least likely to occur. If these morning abnormalities in DMN are pertinent to disease expression, then similar or further detectable differences may be expected on a nighttime assessment when RLS symptom threshold is at its lowest. The purpose of this study was to elucidate the potential neural mechanisms underlying the circadian aspect of RLS symptom expression by assessing diurnal changes in DMN.</P> <P><B>Methods</B></P> <P>Fifteen drug-naïve subjects with idiopathic RLS and 15 age- and gender-matched healthy subjects had fMRI scans in the morning and evening. The DMN patterns were compared both for differences between morning and evening and between RLS and controls.</P> <P><B>Results</B></P> <P>RLS patients compared to the healthy controls showed significant differences in morning and evening DMN. In particular, RLS patients showed consistent increased connectivity in the parietal lobule in both the morning and evening. In contrast, connectivity in the thalamus was increased in the morning and reduced in the evening. In addition, there were negative correlations between thalamic connectivity and the Korean versions of the international RLS scale and the quality-of-life subscore.</P> <P><B>Conclusions</B></P> <P>The results indicated diurnal disturbances of the DMN in RLS subjects are consistent with both the circadian rhythm and severity of RLS. The circadian expression of RLS may relate to changes in arousal cortical-activation thresholds occurring with diurnal changes in the thalamic circuits of the DMN.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Diurnal changes in the brain with RLS symptoms could elucidate symptom dynamics. </LI> <LI> Daytime DMN, thalamic, and sensorimotor networks suggest solutions for RLS symptoms. </LI> <LI> Evening thalamic reduction with sustained sensorimotor activation controls symptom emergence. </LI> <LI> The results suggest RLS is a disorder of the disturbed sensory activation/threshold. </LI> <LI> The results could provide clinical provision for symptom emergence and treatment. </LI> </UL> </P>

Altered white matter integrity in primary restless legs syndrome patients: diffusion tensor imaging study.

Chang, Yongmin,Paik, Jong Soo,Lee, Hui Joong,Chang, Hyuk Won,Moon, Hye-Jin,Allen, Richard P,Earley, Christopher J,Cho, Yong Won Butterworths [etc.] 2014 Neurological research Vol.36 No.8

<P>A prior diffusion tensor imaging (DTI) of restless legs syndrome (RLS) subjects found alterations in brain white matter (WM). The aim of this study was to explore the possible mechanism of altered integrity of brain WM in RLS patients.</P>

자기(磁氣) 목걸이 : 목과 어깨의 통증에 미치는 치료효과

Hong, Chang-Zern,Lin, James C.,Bender, Leonard F.,Schaeffer, Joseph D.,Meltzer, Richard J.,Causin, Pastor,문명상 최신의학사 1983 最新醫學 Vol.26 No.5

Design of an Optically Controlled MR-Compatible Active Needle

Seok Chang Ryu,Zhan Fan Quek,Je-Sung Koh,Renaud, Pierre,Black, Richard J.,Moslehi, Behzad,Daniel, Bruce L.,Kyu-Jin Cho,Cutkosky, Mark R. IEEE 2015 IEEE TRANSACTIONS ON ROBOTICS Vol. No.

<P>An active needle is proposed for the development of magnetic resonance imaging (MRI)-guided percutaneous procedures. The needle uses a low-transition-temperature shape memory alloy (LT SMA) wire actuator to produce bending in the distal section of the needle. Actuation is achieved with internal optical heating using laser light transported via optical fibers and side coupled to the LT SMA. A prototype, with a size equivalent to a standard 16-gauge biopsy needle, exhibits significant bending, with a tip deflection of more than 14° in air and 5° in hard tissue. A single-ended optical sensor with a gold-coated tip is developed to measure the curvature independently of temperature. The experimental results in tissue phantoms show that human tissue causes fast heat dissipation from the wire actuator; however, the active needle can compensate for typical targeting errors during prostate biopsy.</P>

Recovery from minimally invasive vs. open surgery in kidney cancer patients: Opioid use and workplace absenteeism

Marieke J. Krimphove,Stephen W. Reese,Xi Chen,Maya Marchese,Daniel Pucheril,Eugene Cone,Wesley Chou,Karl H. Tully,Adam S. Kibel,Richard D. Urman,Steven L. Chang,Luis A. Kluth,Prokar Dasgupta,Quoc-Dien 대한비뇨의학회 2021 Investigative and Clinical Urology Vol.62 No.1

Purpose: Does surgical approach (minimally invasive vs. open) and type (radical vs. partial nephrectomy) affects opioid use and workplace absenteeism. Materials and Methods: Retrospective multivariable regression analysis of 2,646 opioid-naïve patients between 18 and 64 undergoing radical or partial nephrectomy via either a minimally invasive vs. open approach for kidney cancer in the United States between 2012 and 2017 drawn from the IBM Watson Health Database was performed. Outcomes included: (1) opioid use in opioid-naïve patients as measured by opioid prescriptions in the post-operative setting at early, intermediate and prolonged time periods and (2) workplace absenteeism after surgery. Results: Patients undergoing minimally invasive surgery had a lower odds of opioid use in the early and intermediate post-operative periods (early: odds ratio [OR], 0.77; 95% confidence interval [CI], 0.62–0.97; p=0.02, intermediate: OR, 0.60; 95% CI, 0.48–0.75; p<0.01), but not in the prolonged setting (prolonged: OR, 1.00; 95% CI, 0.75–1.34; p=0.98) and had earlier return to work (minimally invasive vs. open: −10.53 days; 95% CI, −17.79 to −3.26; p<0.01). Controlling for approach, patient undergoing partial nephrectomy had lower rates of opioid use across all time periods examined and returned to work earlier than patients undergoing radical nephrectomy (partial vs. radical: −14.41 days; 95% CI, −21.22 to −7.60; p<0.01). Conclusions: Patients undergoing various forms of surgery for kidney cancer had lower rates of peri-operative opioid use, fewer days of workplace absenteeism, but no difference in long-term rates of opioid use in patients undergoing minimally invasive as compared to open surgery.

Vertical mixing due to double diffusion in the tropical western Pacific : Vertical mixing due to double diffusion

Lee, Chorong,Chang, Kyung-Il,Lee, Jae Hak,Richards, Kelvin J. American Geophysical Union 2014 Geophysical research letters Vol.41 No.22

THE NEW HORIZON RUN COSMOLOGICAL N-BODY SIMULATIONS

Kim, Ju-Han,Park, Chang-Bom,Rossi, Graziano,Lee, Sang-Min,Gott, J. Richard III The Korean Astronomical Society 2011 Journal of The Korean Astronomical Society Vol.44 No.6

We present two large cosmological N-body simulations, called Horizon Run 2 (HR2) and Horizon Run 3 (HR3), made using $6000^3$ = 216 billions and $7210^3$ = 374 billion particles, spanning a volume of $(7.200\;h^{-1}Gpc)^3$ and $(10.815\;h^{-1}Gpc)^3$, respectively. These simulations improve on our previous Horizon Run 1 (HR1) up to a factor of 4.4 in volume, and range from 2600 to over 8800 times the volume of the Millennium Run. In addition, they achieve a considerably finer mass resolution, down to $1.25{\times}10^{11}h^{-1}M_{\odot}$, allowing to resolve galaxy-size halos with mean particle separations of $1.2h^{-1}$Mpc and $1.5h^{-1}$Mpc, respectively. We have measured the power spectrum, correlation function, mass function and basic halo properties with percent level accuracy, and verified that they correctly reproduce the CDM theoretical expectations, in excellent agreement with linear perturbation theory. Our unprecedentedly large-volume N-body simulations can be used for a variety of studies in cosmology and astrophysics, ranging from large-scale structure topology, baryon acoustic oscillations, dark energy and the characterization of the expansion history of the Universe, till galaxy formation science - in connection with the new SDSS-III. To this end, we made a total of 35 all-sky mock surveys along the past light cone out to z = 0.7 (8 from the HR2 and 27 from the HR3), to simulate the BOSS geometry. The simulations and mock surveys are already publicly available at http://astro.kias.re.kr/Horizon-Run23/.

Contrast in Life Histories of Exploited Fishes and Ecosystem Structures in Coastal Waters off West Canada and East Korea

McFarlane, Gordon A.,Zhang, Chang Ik,King, Jacquelynne R.,Kim, Su-Am,Beamish, Richard J.,Oh, Jae-Ho 한국해양학회 2009 Ocean science journal Vol.44 No.1

By reviewing the history of fishery exploitation in the coastal waters of west Canada and east Korea, related with contrasting life history strategies of the dominant species, the fishery management challenges that each country would face in the upcoming decades were outlined. In the ecosystem of the Canadian western coastal waters, the dominant oceanographic feature is the coastal upwelling domain off the west coast of Vancouver Island, the northernmost extent of the California Current System in the eastern North Pacific. In the marine ecosystem of the eastern coasts of Korea (the Japan/East Sea), a major oceanographic feature is the Tsushima Warm Current, a branch of the Kuroshio Current in the western North Pacific. Fishes in the Canadian ecosystem are dominated by demersal, long-lived species such as flatfish, rockfish, sablefish, and halibut. During summer, migratory pelagic species such as Pacific hake, Pacific salmon, and recently Pacific sardine, move into this area to feed. In the late 1970s, Canada declared jurisdiction for 200 miles from their coastline, and major fisheries species in Canadian waters have been managed with a quota system. The overall fishing intensity off the west coast of Vancouver Island has been relatively moderate compared to Korean waters. Fishes in the ecosystem of the eastern Korean waters are dominated by shortlived pelagic and demersal fish. Historically, Korea has shared marine resources in this area with neighbouring countries, but stock assessments and quotas have only recently (since the late-1990s) been implemented for some major species. In the Korean ecosystem, fisheries can be described as intensive, and many stocks have been rated as overfished. The two ecosystems responded differently to climate impacts such as regime shifts under different exploitation histories. In the future, both countries will face the challenge of global warming and subsequent impacts on ecosystems, necessitating developing adaptive fisheries management plans. The challenges will be contrasting for the two countries: Canada will need to conserve fish populations, while Korea will need to focus on rebuilding depleted fish populations.