Stochastic chaos and thermodynamic phase transitions : theory and Bayesian estimation algorithms

Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 177-200).The chaotic behavior of dynamical systems underlies the foundations of statistical mechanics through ergodic theory. This putative connection is made more concrete in Part I of this thesis, where we show how to quantify certain chaotic properties of a system that are of relevance to statistical mechanics and kinetic theory. We consider the motion of a particle trapped in a double-well potential coupled to a noisy environment. By use of the classic Langevin and Fokker-Planck equations, we investigate Kramers' escape rate problem. We show that there is a deep analogy between kinetic rate theory and stochastic chaos, for which we propose a novel definition. In Part II, we develop techniques based on Volterra series modeling and Bayesian non-linear filtering to distinguish between dynamic noise and measurement noise. We quantify how much of the system's ergodic behavior can be attributed to intrinsic deterministic dynamical properties vis-a-vis inevitable extrinsic noise perturbations.by Zhi-De Deng.M.Eng.and S.B

Sediment transport rate-based model for rainfall-induced soil erosion

http://www.sciencedirect.com/science/article/B6VCG-4TP7HC2-1/2/2a6275ceb0176f80cedfb5efe5ef248

Efficacy and adverse effects of transdermal fentanyl and sustained-release oral morphine in treating moderate-severe cancer pain in Chinese population: a systematic review and meta-analysis

<p>Abstract</p> <p>Background</p> <p>Previous meta-analysis suggested that transdermal fentanyl was not inferior to sustained-release oral morphine in treating moderate-severe cancer pain with less adverse effects. Now, we updated the data and performed a systematic review.</p> <p>Methods</p> <p>Updated cohort studies on transdermal fentanyl and oral morphine in the treatment of cancer pain were searched in electronic databases including CBMdisc, CNKI, VIP, Medline, EMBASE and Cochrane Library. Primary end points assessed by meta-analysis were remission rate of pain and incidence of adverse effects. Quality of life was assessed by systematic review, which was the second end point.</p> <p>Results</p> <p>32 cohort studies, which included 2651 patients, were included in present study. The remission rate in transdermal fentanyl group and sustained-release oral morphine group were 86.60% and 88.31% respectively, there was no significant difference [RR = 1.13, 95% CI (0.92, 1.38), P = 0.23]. Compared with oral morphine group, there were less adverse effects in terms of constipation [RR = 0.35, 95% CI (0.27, 0.45), P < 0.00001], nausea/vomiting [RR = 0.57, 95% CI (0.49, 0.67), P < 0.00001], and vertigo/somnolence [RR = 0.59, 95% CI (0.51, 0.68), P < 0.00001] in transdermal fentanyl group. Six of selected trials supported either transdermal fentanyl or sustained-release oral morphine improved QOL of cancer patients and one of them showed more patients got better QOL after sustained-release oral morphine transferred to transdermal fentanyl.</p> <p>Conclusions</p> <p>Our study showed again that both transdermal fentanyl and oral morphine had the same efficacy in the treatment of moderate-severe cancer pain in Chinese population, but the former might have less adverse effects and better quality of life.</p

Modulation of Resting Connectivity Between the Mesial Frontal Cortex and Basal Ganglia.

Background: The mesial prefrontal cortex, cingulate cortex, and the ventral striatum are key nodes of the human mesial fronto-striatal circuit involved in decision-making and executive function and pathological disorders. Here we ask whether deep wide-field repetitive transcranial magnetic stimulation (rTMS) targeting the mesial prefrontal cortex (MPFC) influences resting state functional connectivity. Methods: In Study 1, we examined functional connectivity using resting state multi-echo and independent components analysis in 154 healthy subjects to characterize default connectivity in the MPFC and mid-cingulate cortex (MCC). In Study 2, we used inhibitory, 1 Hz deep rTMS with the H7-coil targeting MPFC and dorsal anterior cingulate (dACC) in a separate group of 20 healthy volunteers and examined pre- and post-TMS functional connectivity using seed-based and independent components analysis. Results: In Study 1, we show that MPFC and MCC have distinct patterns of functional connectivity with MPFC-ventral striatum showing negative, whereas MCC-ventral striatum showing positive functional connectivity. Low-frequency rTMS decreased functional connectivity of MPFC and dACC with the ventral striatum. We further showed enhanced connectivity between MCC and ventral striatum. Conclusions: These findings emphasize how deep inhibitory rTMS using the H7-coil can influence underlying network functional connectivity by decreasing connectivity of the targeted MPFC regions, thus potentially enhancing response inhibition and decreasing drug-cue reactivity processes relevant to addictions. The unexpected finding of enhanced default connectivity between MCC and ventral striatum may be related to the decreased influence and connectivity between the MPFC and MCC. These findings are highly relevant to the treatment of disorders relying on the mesio-prefrontal-cingulo-striatal circuit

Extended Remediation of Sleep Deprived-Induced Working Memory Deficits Using fMRI-Guided Transcranial Magnetic Stimulation

STUDY OBJECTIVES: We attempted to prevent the development of working memory (WM) impairments caused by sleep deprivation using fMRI-guided repetitive transcranial magnetic stimulation (rTMS). Novel aspects of our fMRI-guided rTMS paradigm included the use of sophisticated covariance methods to identify functional networks in imaging data, and the use of fMRI-targeted rTMS concurrent with task performance to modulate plasticity effects over a longer term. DESIGN: Between-groups mixed model. SETTING: TMS, MRI, and sleep laboratory study. PARTICIPANTS: 27 subjects (13 receiving Active rTMS, and 14 Sham) completed the sleep deprivation protocol, with another 21 (10 Active, 11 Sham) non-sleep deprived subjects run in a second experiment. INTERVENTIONS: Our previous covariance analysis had identified a network, including occipital cortex, which demonstrated individual differences in resilience to the deleterious effects of sleep deprivation on WM performance. Five Hz rTMS was applied to left lateral occipital cortex while subjects performed a WM task during 4 sessions over the course of 2 days of total sleep deprivation. MEASUREMENTS AND RESULTS: At the end of the sleep deprivation period, Sham sleep deprived subjects exhibited degraded performance in the WM task. In contrast, those receiving Active rTMS did not show the slowing and lapsing typical in sleep deprivation, and instead performed similarly to non- sleep deprived subjects. Importantly, the Active sleep deprivation group showed rTMS-induced facilitation of WM performance a full 18 hours after the last rTMS session. CONCLUSIONS: Over the course of sleep deprivation, these results indicate that rTMS applied concurrently with WM task performance affected neural circuitry involved in WM to prevent its full impact

A fractional dispersion model for overland solute transport

An edited version of this paper was published by AGU. Copyright 2006 American Geophysical Union.Using the kinematic-wave overland flow equation and a fractional dispersion-advection equation, a process-oriented, physically-based model is developed for overland solute transport. Two scenarios, one consisting of downslope and the other of upslope rainstorm movements, are considered for numerical computations. Under these conditions, the hydrograph displays a long-tailed distribution due to the variation in flow velocity in both time and distance. The solute transport exhibits a complex behavior. Pollutographs are characterized by a steep rising limb, with a peak, and a long, stretched receding limb; whereas the solute concentration distributions feature a rapid receding limb followed by a long stretched rising limb. Downslope moving storms cause much higher peak in both hydrographs and pollutographs than do upslope moving storms. Both hydrographs and the pollutographs predicted by the fractional dispersion model are in good agreement with the data measured experimentally using a soil flume and a moving rainfall simulator

GISSD: Group I Intron Sequence and Structure Database

Group I Intron Sequence and Structure Database (GISSD) is a specialized and comprehensive database for group I introns, focusing on the integration of useful group I intron information from available databases and providing de novo data that is essential for understanding these introns at a systematic level. This database presents 1789 complete intron records, including the nucleotide sequence of each annotated intron plus 15 nt of the upstream and downstream exons, and the pseudoknots-containing secondary structures predicted by integrating comparative sequence analyses and minimal free energy algorithms. These introns represent all 14 subgroups, with their structure-based alignments being separately provided. Both structure predictions and alignments were done manually and iteratively adjusted, which yielded a reliable consensus structure for each subgroup. These consensus structures allowed us to judge the confidence of 20 085 group I introns previously found by the INFERNAL program and to classify them into subgroups automatically. The database provides intron-associated taxonomy information from GenBank, allowing one to view the detailed distribution of all group I introns. CDSs residing in introns and 3D structure information are also integrated if available. About 17 000 group I introns have been validated in this database; ∼95% of them belong to the IC3 subgroup and reside in the chloroplast tRNALeu gene. The GISSD database can be accessed at http://www.rna.whu.edu.cn/gissd