Multivariate Spatio-temporal modeling and simulation

Doctor of PhilosophyDepartment of StatisticsJuan DuIn view of multivariate nature of general spatio-temporal data sets observed in various disciplines such as meteorology, engineering and medical science, we are interested in gaining some scientific insight into the underlying stochastic processes, which incorporate the complex dependence structure among different variables at different locations over time. To this end, this dissertation studies the methods and applications of the multivariate modelling, simulation and missing value imputation of data sets in space and time under different settings. Chapter I, Space-time data sets are often multivariate and collected at monitored discrete time lags, which are usually viewed as a component of time series in environmental science and related areas. Valid and practical covariance models are needed to characterize geostatistical formulations of these types of data sets in a wide range of applications. We propose several classes of multivariate spatio-temporal functions to characterize underlying random fields whose discrete temporal margins are some celebrated autoregressive and moving average (ARMA) models, and obtain sufficient and/or necessary conditions for them to be valid covariance matrix functions. The possibility of taking advantage of well-established time series and spatial statistics tools makes it relatively straightforward to identify and fit the proposed models in practice. Finally, applications of the proposed multivariate covariance matrix functions are illustrated on Kansas weather data in terms of co-kriging, compared with some traditional space-time models for prediction. Chapter II, We propose an efficient method for simulating multivariate spatio-temporal data on a compact two-point homogeneous space with sphere as a special case. These large scale global data sets are obtained based on truncating the series expansion of multivariate spatio-temporal random fields on this space. The algorithm can be boiled down to simply simulate a uniformly distributed random vector on a sphere, on which the great circle distance is defined. Multiple covariance models are compared to fit the simulated multivariate space-time data including the model proposed in the Chapter I. The simulation studies suggest some guideline for choosing appropriate models and parameterizations for different multivariate data in space and time. Chapter III, Motivated by dealing with incompleteness of energy data to study network situational awareness, we proposed a spatial Gaussian process variational autoencoders (GP-VAE) to impute the corrupted or missing information based on multivariate Gaussian processes and Bayesian deep learning. The missing data is learned by projecting the multivariate data space including both space and time into a lower dimensional latent space without missingness, where the low dimensional dynamics is modeled with vector Gaussian time series. Model comparison has been made with traditional data imputation method in literature on a simulated energy data set from smart meters, solar inverters, grid automation/SCADA sensors and micro PMU on a geographical lattice over time

Resection, including transplantation, for hepatoblastoma and hepatocellular carcinoma: Impact on survival

Long-term survival in children with primary hepatic malignancies can not be expected without complete tumor resection. In the last ten years we have treated 21 children with hepatocellular carcinoma (HCC) and 21 children with hepatoblastoma (HEP), with tumor extirpation our surgical goal. Operative treatment included partial hepatectomy ([PH] 20), either primary (10) or delayed (following chemotherapy) (10), total hepatectomy and orthotopic liver transplantation ([OLT] 13), or upper abdominal exenteration and multiple organ transplantation (2). Two patients had both PH and subsequent total hepatectomy and OLT. Overall survival was 48% ( 20 42), with 9 patients dying of progressive disease prior to removal of their tumor. HEP patient survival was 67% ( 14 21), including 2 of 6 who underwent primary PH, 7 of 8 who had delayed PH, and 5 of 6 who underwent OLT. Survival for the children with HCC was 29% ( 6 21), including 1 of 4 after primary PH, 1 of 2 following delayed PH, 3 of 7 following OLT, and 1 of 2 after exenteration and multiple organ transplantation. Preoperative chemotherapy facilitated removal of 10 initially unresectable tumors (8 HEP, 2 HCC) at a second-look procedure. Total hepatectomy and OLT markedly improved survival in patients with disease unresectable by standard methods. Partial hepatectomy, either primary or delayed, should be attempted in all children with hepatic malignancies. Total hepatectomy and OLT appears to be a viable adjunct in the treatment of childhood malignancies, and should be used for otherwise unresectable tumors as part of a carefully planned protocol. © 1992

Impact of Prostate Volume on the Efficacy of High-Power Potassium-Titanyl-Phosphate Photoselective Vaporization of the Prostate: A Retrospective, Short-Term Follow-Up Study on Evaluating Feasibility and Safety

Purpose: We determined the impact of prostate volume on the efficacy of the high-power (80 W) potassium-titanyl-phosphate (KTP) photoselective laser vaporization of the prostate in men with lower urinary tract symptoms (LUTS). Materials and Methods: Patients were stratified into 3 groups according to prostate volume: `<40 g` (n = 49) and `40-59 g` (n = 49) and 60 g` (n = 22). Median follow-up was 9 months (range 6 to 21). Results: No differences in age and follow-up duration were observed in the three groups. At baseline, no significant differences were noted in the three groups in terms of the International Prostate Symptom Score (IPSS) (21.4, 19.4 and 19.1; p = 0.412) as well as the maximum flow rate (Qmax) (10.2, 9.2, and 8.6 mL/s; p = 0.291) and post-void residual (PVR) (66.2, 80.4, and 71.5 mL; p = 0.856). The mean operative times were 30.9, 46.9, and 58.6 minutes (p < 0.001) and total median energy deliveries for each group were 62.3, 97.6, and 135.9 kJ, respectively (p < 0.001). No severe intraoperative complication was observed. At the last follow-up, these parameters improved significantly regardless of prostate volume, and the IPSS (11.1, 9.4, and 12.3; p = 0.286) as well as Qmax (15.9, 15.9, and 14.2 mL/s; p = 0.690) and PVR (33.7, 28.4, and 14.2 mL; p = 0.395) were not significantly different among the groups. Conclusion: Although a larger prostate requires more time and energy delivery, photoselective laser vaporization of the prostate is safe and efficacious for patients with LUTS regardless of prostate volume.Spaliviero M, 2008, J ENDOUROL, V22, P2341, DOI 10.1089/end.2008.9708Rieken M, 2010, WORLD J UROL, V28, P53, DOI 10.1007/s00345-009-0504-zNaspro R, 2009, EUR UROL, V55, P1345, DOI 10.1016/j.eururo.2009.03.070Lee R, 2008, J UROLOGY, V180, P1551, DOI 10.1016/j.juro.2008.06.002Du CJ, 2008, J ENDOUROL, V22, P1031, DOI 10.1089/end.2007.0262Paick JS, 2007, J SEX MED, V4, P1701, DOI 10.1111/j.1743-6109.2007.00574.xMonoski MA, 2006, UROLOGY, V68, P312, DOI 10.1016/j.urology.2006.02.020Bouchier-Hayes DM, 2006, J ENDOUROL, V20, P580Te AE, 2006, BJU INT, V97, P1229, DOI 10.1111/j.1464-410X.2006.06197.xKrambeck AE, 2010, J ENDOUROL, V24, P433, DOI 10.1089/end.2009.0147Fu WJ, 2006, ASIAN J ANDROL, V8, P367, DOI 10.1111/j.1745-7262.2006.00134.xBarber NJ, 2006, UROLOGY, V67, P80, DOI 10.1016/j.urology.2005.07.028Bachmann A, 2005, EUR UROL, V48, P965, DOI 10.1016/j.eururo.2005.07.001Sandhu JS, 2005, J ENDOUROL, V19, P1196Sarica K, 2005, J ENDOUROL, V19, P1199Malek RS, 2005, J UROLOGY, V174, P1344, DOI 10.1097/01.ju.0000173913.41401.67Volkan T, 2005, EUR UROL, V48, P608, DOI 10.1016/j.eururo.2005.07.013Bachmann A, 2005, EUR UROL, V47, P798, DOI 10.1016/j.eururo.2005.02.003Kumar SM, 2005, J UROLOGY, V173, P511, DOI 10.1097/01.ju.0000150099.31289.d7Reich O, 2005, J UROLOGY, V173, P158, DOI 10.1097/01.ju.0000146631.14200.d4Sandhu JS, 2004, UROLOGY, V64, P1155Sulser T, 2004, J ENDOUROL, V18, P976Te AE, 2004, J UROLOGY, V172, P1404, DOI 10.1097/01.ju.0000139541.68542.f6Reich O, 2004, J UROLOGY, V171, P2502, DOI 10.1097/01.ju.0000128803.04158.76Hai MA, 2003, J ENDOUROL, V17, P93Shingleton WB, 1999, UROLOGY, V54, P1017Shingleton WB, 1998, SCAND J UROL NEPHROL, V32, P266Kuntzman RS, 1997, UROLOGY, V49, P703Kuntzman RS, 1996, UROLOGY, V48, P575

Uncovering the Global Life Cycles of the Rare Earth Elements

The rare earth elements (REE) are a group of fifteen elements with unique properties that make them indispensable for a wide variety of emerging, critical technologies. Knowledge of the life cycles of REE remains sparse, despite the current heightened interest in their future availability. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supplies vulnerable to short and long-term disruption. To provide an improved perspective we derived the first quantitative life cycles (for the year 2007) for ten REE: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), and yttrium (Y). Of these REE, Ce and Nd in-use stocks are highest; the in-use stocks of most REE show significant accumulation in modern society. Industrial scrap recycling occurs only from magnet manufacture. We believe there is no post-customer recycling of any of these elements

Adenosine A2A Receptors Mediate Anti-Inflammatory Effects of Electroacupuncture on Synovitis in Mice with Collagen-Induced Arthritis

To study the role of adenosine A2A receptor (A2AR) in mediating the anti-inflammatory effect of electroacupuncture (EA) on synovitis in collagen-induced arthritis (CIA), C57BL/6 mice were divided into five treatment groups: Sham-control, CIA-control, CIA-EA, CIA-SCH58261 (A2AR antagonist), and CIA-EA-SCH58261. All mice except those in the Sham-control group were immunized with collagen II for arthritis induction. EA treatment was administered using the stomach 36 and spleen 6 points, and stimulated with a continuous rectangular wave for 30 min daily. EA treatment and SCH58261 were administered daily from days 35 to 49 (n=10). After treatment, X-ray radiography of joint bone morphology was established at day 60 and mouse blood was collected for ELISA determination of tumor necrosis factor alpha (TNF-α) levels. Mice were sacrificed and processed for histological examination of pathological changes of joint tissue, including hematoxylin-eosin staining and immunohistochemistry of A2AR expression. EA treatment resulted in significantly reduced pathological scores, TNF-α concentrations, and bone damage X-ray scores. Importantly, the anti-inflammatory and tissue-protective effect of EA treatment was reversed by coadministration of SCH58261. Thus, EA treatment exerts an anti-inflammatory effect resulting in significant protection of cartilage by activation of A2AR in the synovial tissue of CIA

Repeated Electroacupuncture Persistently Elevates Adenosine and Ameliorates Collagen-Induced Arthritis in Rats

The aim of this paper was to investigate the effect of repeated electroacupuncture (EA) over 21 days on the adenosine concentration in peripheral blood of rats with collagen-induced arthritis (CIA). Wistar rats were divided into three groups of 6 animals each: sham-control, CIA-control, and CIA-EA. We determined the adenosine concentration in peripheral blood and assessed pathological changes of ankle joints. Quantitative reverse-transcription-polymerase chain reaction was used to determine mRNA levels of ecto-5′-nucleotidase (CD73), adenosine deaminase (ADA), and tumor necrosis factor-alpha (TNF-α). Immunohistochemical staining was used to detect expression of ADA and CD73 in synovial tissue. Repeated EA treatment on CIA resulted in the persistence of high concentrations of adenosine in peripheral blood, significantly reduced pathological scores, TNF-α mRNA concentrations, and synovial hyperplasia. Importantly, EA treatment led to a significant increase in CD73 mRNA levels in peripheral blood but was associated with a decrease of CD73 immunostaining in synovial tissue. In addition, EA treatment resulted in a significant decrease of both ADA mRNA levels in peripheral blood and ADA immunostaining in synovial tissue. Thus, repeated EA treatment exerts an anti-inflammatory and immunoregulatory effect on CIA by increasing the concentration of adenosine. The mechanism of EA action may involve the modulation of CD73 and ADA expression levels

Giant X-ray circular dichroism in a time-reversal invariant altermagnet

X-ray circular dichroism, arising from the contrast in X-ray absorption between opposite photon helicities, serves as a spectroscopic tool to measure the magnetization of ferromagnetic materials and identify the handedness of chiral crystals. Antiferromagnets with crystallographic chirality typically lack X-ray magnetic circular dichroism because of time-reversal symmetry, yet exhibit weak X-ray natural circular dichroism. Here, we report the observation of giant natural circular dichroism in the Ni $L_3$-edge X-ray absorption of Ni$_3$TeO$_6$, a polar and chiral antiferromagnet with effective time-reversal symmetry. To unravel this intriguing phenomenon, we propose a phenomenological model that classifies the movement of photons in a chiral crystal within the same symmetry class as that of a magnetic field. The coupling of X-ray polarization with the induced magnetization yields giant X-ray natural circular dichroism, revealing the altermagnetism of Ni$_3$TeO$_6$. Our findings provide evidence for the interplay between magnetism and crystal chirality in natural optical activity. Additionally, we establish the first example of a new class of magnetic materials exhibiting circular dichroism with time-reversal symmetry.Comment: Accepted by Advanced Materials (2024.2.16) Revised title: Giant X-ray circular dichroism in a time-reversal invariant altermagnet Revised drafts: Main 14 pages, 4 figures, and SI 20 pages, 8 figure