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154. Property $T$ of reduced $C^*$-crossed products by discrete groups

Author

Jiang, Baojie and Ng, Chi-Keung

Subjects
Mathematics - Operator Algebras
Abstract

We generalize the main result of Kamalov and show that if $G$ is an amenable discrete group with an action $\alpha$ on a finite nuclear unital $C^*$-algebra $A$ such that the reduced crossed product $A\rtimes_{\alpha,r} G$ has property $T$, then $G$ is finite and $A$ is finite dimensional. As an application, an infinite discrete group $H$ is non-amenable if and only if the uniform Roe algebra $C^*_u(H)$ has property $T$.

Published
2015
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155. The positive contractive part of a Noncommutative $L^p$-space is a complete Jordan invariant

Author

Leung, Chi-Wai, Ng, Chi-Keung, and Wong, Ngai-Ching

Subjects
Mathematics - Operator Algebras, 46L10, 46L52
Abstract

Let $1\leq p \leq +\infty$. We show that the positive part of the closed unit ball of a non-commmutative $L^p$-space, as a metric space, is a complete Jordan $^*$-invariant for the underlying von Neumann algebra., Comment: 8 pages

Published
2015

156. Transition probabilities of normal states determine the Jordan structure of a quantum system

Author

Leung, Chi-Wai, Ng, Chi-Keung, and Wong, Ngai-Ching

Subjects
Mathematical Physics, Mathematics - Operator Algebras
Abstract

Let $\Phi:\mathfrak{S}(M_1)\to \mathfrak{S}(M_2)$ be a bijection (not assumed affine nor continuous) between the sets of normal states of two quantum systems, modelled on the self-adjoint parts of von Neumann algebras $M_1$ and $M_2$, respectively. This paper concerns with the situation when $\Phi$ preserves (or partially preserves) one of the following three notions of "transition probability" on the normal state spaces: the Uhlmann transition probability $P_U$, the Raggio transition probability $P_B$ and an "asymmetric transition probability" $P_0$ as defined in this article. It is shown that the two systems are isomorphic, i.e. $M_1$ and $M_2$ are Jordan $^*$-isomorphic, if $\Phi$ preserves all pairs with zero Uhlmann (respectively, Raggio or asymmetric) transition probability, i.e., for any normal states $\mu$ and $\nu$, we have $$ P\big(\Phi(\mu),\Phi(\nu)\big) = 0 \quad \text{if and only if} \quad P(\mu,\nu)=0, $$ where $P$ stands for $P_U$ (respectively, $P_R$ or $P_0$). Furthermore, as an extension of Wigner's theorem, it is shown that there is a Jordan $^*$-isomorphism $\Theta:M_2\to M_1$ with $$\Phi = \Theta^*|_{\mathfrak{S}(M_1)}$$ if and only if $\Phi$ preserves the "asymmetric transition probability". This is also equivalent to $\Phi$ preserving the Raggio transition probability. Consequently, if $\Phi$ preserves the Raggio transition probability, it will preserve the Uhlmann transition probability as well. As another application, the sets of normal states equipped with either the usual metric, the Bures metric or "the metric induced by the self-dual cone" are complete Jordan $^*$-invariants for the underlying von Neumann algebras., Comment: 17 pages

Published
2015
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157. Property $T$ for general locally compact quantum groups

Author

Chen, Xiao and Ng, Chi-Keung

Subjects
Mathematics - Quantum Algebra, Mathematics - Functional Analysis, Mathematics - Operator Algebras, Primary 20G42, 46L89 Secondary 22D25
Abstract

In this short article, we obtained some equivalent formulations of property $T$ for a general locally compact quantum group $\mathbb{G}$, in terms of the full quantum group $C^*$-algebras $C_0^\mathrm{u}(\widehat{\mathbb{G}})$ and the $*$-representation of $C_0^\mathrm{u}(\widehat{\mathbb{G}})$ associated with the trivial unitary corepresentation (that generalize the corresponding results for locally compact groups). Moreover, if $\mathbb{G}$ is of Kac type, we show that $\mathbb{G}$ has property $T$ if and only if every finite dimensional irreducible $*$-representation of $C_0^\mathrm{u}(\widehat{\mathbb{G}})$ is an isolated point in the spectrum of $C_0^\mathrm{u}(\widehat{\mathbb{G}})$ (this also generalizes the corresponding locally compact group result). In addition, we give a way to construct property $T$ discrete quantum groups using bicrossed products., Comment: 12 pages; accepted for publication in Int. J. Math

Published
2015

158. A property for locally convex $^*$-algebras related to Property $(T)$ and character amenability

Author

Chen, Xiao, Lau, Anthony To-Ming, and Ng, Chi-Keung

Subjects
Mathematics - Functional Analysis, Primary 22D15, 22D20, 46K10, Secondary 22D10, 22D12, 16E40, 43A07, 46H15
Abstract

For a locally convex $^*$-algebra $A$ equipped with a fixed continuous $^*$-character $\varepsilon$, we define a cohomological property, called property $(FH)$, which is similar to character amenability. Let $C_c(G)$ be the space of continuous functions on a second countable locally compact group $G$ with compact supports, equipped with the convolution $^*$-algebra structure and a certain inductive topology. We show that $(C_c(G), \varepsilon_G)$ has property $(FH)$ if and only if $G$ has property $(T)$. On the other hand, many Banach algebras equipped with canonical characters have property $(FH)$ (e.g., those defined by a nice locally compact quantum group). Furthermore, through our studies on both property $(FH)$ and character amenablility, we obtain characterizations of property $(T)$, amenability and compactness of $G$ in terms of the vanishing of one-sided cohomology of certain topological algebras, as well as in terms of fixed point properties. These characterizations can be regarded as analogues of one another. Moreover, we show that $G$ is compact if and only if the normed algebra $\big\{f\in C_c(G): \int_G f(t)dt =0\big\}$ (under $\|\cdot\|_{L^1(G)}$) admits a bounded approximate identity with the supports of all its elements being contained in a common compact set., Comment: 24 pages, accepted for publication in Studia Mathematica

Published
2015

159. Regularized LRT for Large Scale Covariance Matrices: One Sample Problem

Author

Choi, Young-Geun, Ng, Chi Tim, and Lim, Johan

Subjects
Statistics - Methodology, 62H15, 62H10
Abstract

The main theme of this paper is a modification of the likelihood ratio test (LRT) for testing high dimensional covariance matrix. Recently, the correct asymptotic distribution of the LRT for a large-dimensional case (the case $p/n$ approaches to a constant $\gamma \in (0,1]$) is specified by researchers. The correct procedure is named as corrected LRT. Despite of its correction, the corrected LRT is a function of sample eigenvalues that are suffered from redundant variability from high dimensionality and, subsequently, still does not have full power in differentiating hypotheses on the covariance matrix. In this paper, motivated by the successes of a linearly shrunken covariance matrix estimator (simply shrinkage estimator) in various applications, we propose a regularized LRT that uses, in defining the LRT, the shrinkage estimator instead of the sample covariance matrix. We compute the asymptotic distribution of the regularized LRT, when the true covariance matrix is the identity matrix and a spiked covariance matrix. The obtained asymptotic results have applications in testing various hypotheses on the covariance matrix. Here, we apply them to testing the identity of the true covariance matrix, which is a long standing problem in the literature, and show that the regularized LRT outperforms the corrected LRT, which is its non-regularized counterpart. In addition, we compare the power of the regularized LRT to those of recent non-likelihood based procedures., Comment: 27 pages, 7 figures

Published
2015
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162. Blockchain-enabled traceability and producer's incentive to outsource delivery.

Author

Yang, Liu, Ni, Yaodong, and Ng, Chi-To

Subjects
BLOCKCHAINS, THIRD-party logistics, MORAL hazard, SUPPLY chains
Abstract

Applications of the blockchain technology in supply chains have attracted extensive attention in both academia and industries. However, little research has investigated the effects of the blockchain technology on firms' operational strategies. In this paper, we investigate the impacts of the traceability enabled by the blockchain technology on a producer's decision whether to outsource delivery to a third-party logistics firm. We find that without the blockchain technology, the logistics firm has a moral hazard—an incentive to set the delivery quality at the lowest level even though improving the delivery quality is for free. The traceability enabled by the blockchain technology can resolve the logistics firm's moral hazard and encourage the producer to improve the production quality. Furthermore, when the delivery is cost-efficient for the producer, the traceability enabled by the blockchain technology motivates the producer to outsource the delivery to the logistics firm; otherwise, the producer's outsourcing decision is not affected. When quality cost is low, the blockchain technology makes the logistics firm improve its delivery quality significantly and encourages the producer to improve the production quality. When the quality cost is moderate, only under certain conditions, the blockchain technology has effects on both parties' decisions. [ABSTRACT FROM AUTHOR]

Published
2023
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163. Laser surface modification of NiTi for medical applications

Author

Ng, Chi-Ho, Man, Hau-Chung, Lawrence, Jonathan, Avis, Nicholas, Waugh, David G., and Shi, Yu

Subjects
610.28, Laser surface treatment, NiTi
Abstract

Regarding the higher demand of the total joint replacement (TJR) and revision surgeries in recent years, an implant material should provide much longer lifetime without failure. Nickel titanium (NiTi) is the most popular shape memory alloy in the industry, especially in medical devices due to its unique mechanical properties such as pseudo-elasticity, damping capacity, shape memory and good biocompatibility. However, concerns of nickel ion release of this alloy still exist if it is implanted for a prolonged period of time. Nickel is well known for the possibility of causing allergic response and degeneration of muscle tissue as well as being carcinogenic for the human body beyond a certain threshold. Therefore, drastically improving the surface properties (e.g. wear resistance) of NiTi is a vital step for its adoption as orthopaedic implants. To overcome the above-mentioned risks, different surface treatment techniques have been proposed and investigated, such as Physical Vapour Deposition (PVD), Chemical Vapour Deposition (CVD), ion implantation, plasma spraying, etc. Yet all of these techniques have similar limitations such as high treatment temperature, poor metallurgical bonding between coated film and substrate, and lower flexibility and efficiency. As a result, laser gas nitriding would be an ideal treatment method as it could overcome these drawbacks. Moreover, the shape memory effect and pseudo-elasticity of NiTi from a reversible phase transformation between the martensitic phase and the austenitic phase are very sensitive to heat. Hence, NiTi implant is subjected to the following provisions of the thermo-mechanical treatment process, and this implant provides desired characteristics. It is important to suggest a surface treatment, which would not disturb the original build-in properties. As a result, the low-temperature methods for substrate have to be employed on the surface of NiTi. This present study aims to investigate the feasibility of applying diffusion laser gas nitriding technique to improve the wettability and wear resistance of NiTi as well as establish the optimization technique. The current report summaries the result of laser nitrided NiTi by continuous-wave (CW) fibre laser in nitrogen environment. The microstructure, surface morphology, wettability, wear resistance of the coating layer has been analysed using scanning electron microscopy (SEM), X-ray diffractometry (XRD), sessile drop technique, 3-D profile measurement and reciprocating wear test. The resulting surface layer is free of cracks, and the wetting behaviour is better than the bare NiTi. The wear resistance of the optimised nitride sample with different hatch patterns is also evaluated using reciprocating wear testing against ultra-high-molecular-weight polyethylene (UHMWPE) in Hanks’ solution. The results indicate that the wear rates of the nitride samples and the UHMWPE counter-part were both significantly reduced. It is concluded that the diffusion laser gas nitriding is a potential low-temperature treatment technique to improve the surface properties of NiTi. This technique can be applied to a femoral head or a bone fixation plates with relatively large surface area and movable components.

Published
2017

169. The Role of Surgery in Metastatic Renal Cell Carcinoma in 2024.

Author

Leung, David KW, Ko, Ivan CH, Siu, Brian WH, Wong, Chris HM, Yuen, Steffi KK, Ng, Chi Fai, and Teoh, Jeremy YC

Abstract

Renal cell carcinoma (RCC) is the most common solid tumour of the kidney and accounts for 3% of all cancers. While immune checkpoint inhibitor (ICI)-based combination therapies have emerged as the first-line treatment for metastatic renal cell carcinoma (mRCC), the role of surgery has become more controversial. This review summarizes the evidence, current role and future directions for surgery in mRCC management. The survival benefits of cytoreductive nephrectomy (CN) shown in the interferon era have encountered increasing disputes in the tyrosine-kinase inhibitor (TKI) and ICI eras. Undoubtedly, several systematic reviews based on retrospective data have supported the survival benefits of CN. Nevertheless, 2 prospective trials, CARMENA and SURTIME, proved that sunitinib as the upfront therapy resulted in noninferior survival outcomes compared with immediate CN. The safety of CN does have solid ground in the current literature. Several studies suggested that preoperative systemic therapy did not seem to aggravate perioperative complications or mortality rates, in experienced centres. Meticulous patient selection is the rule of thumb in the modern management of mRCC patients. The limitations of the existing prognostication models, however, must be acknowledged. Clinicians should adopt a multidisciplinary and holistic approach and contemplate all patient, disease, surgeon and socio-economical factors, before deciding who should go for surgery. The advent of metastasis-directed therapy (MDT) and survival benefits of adjuvant pembrolizumab shown in the oligometastatic subgroup, where complete metastasectomy could be achieved (M1 NED), calls for more comparative studies against upfront ICI combinations. In summary, CN brings survival benefits to well-selected good-to-intermediate-risk mRCC patients. Individualized and multidisciplinary care is pivotal. [ABSTRACT FROM AUTHOR]

Published
2024
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170. Elevated reactive aggression in forebrain‐specific Ccn2 knockout mice.

Author

Chang, Ho‐Ching, Ng, Chi‐Hou, Chen, Yu‐Fu, Wang, Yu‐Chun, Yu, I‐Shing, Lee, Lukas Jyuhn‐Hsiarn, Lee, Li‐Jen, and Lee, Kuang‐Yung

Abstract

Cellular communication network factor 2 (CCN2) is a matricellular protein that plays important roles in connective tissue. CCN2 is also expressed in the nervous system; however, its role is still unclear. To explore CCN2 function in the brain, we generated forebrain‐specific Ccn2 knockout (FbCcn2 KO) mice. In this study, we examined the behavioral phenotypes of FbCcn2KO mice. Male mice lacking CCN2 in the forebrain exhibited normal locomotion, sensorimotor gating, and social behaviors but signs of anxiety and elevated reactive aggression. We checked the c‐fos expression in aggression‐related brain regions following the resident‐intruder task (RIT), an aggression test. RIT‐induced c‐fos levels in the medial amygdala (MeA) were higher in FbCcn2−/− mice as compared to controls. However, in the prefrontal cortex, RIT‐induced c‐fos levels in FbCcn2−/− mice were lower than controls. Our results suggested in male mice lacking CCN2 in the olfaction‐related regions, olfactory social cues elicit greater signals in the MeA, resulting in greater reactive aggression in the RIT. Further, lacking CCN2 in the prefrontal cortex, the major area related to inhibitory control and emotion regulation, may lead to signs of anxiety and the failure to suppress aggressive behaviors. Our model is useful in elaborating the mechanism underlying reactive aggression and therapeutic strategies. [ABSTRACT FROM AUTHOR]

Published
2024
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171. Kidney-Sparing Surgery Has Equivalent Oncological Outcomes to Radical Nephroureterectomy for Ureteral Urothelial Carcinoma.

Author

Liu, Kang, Zhao, Hongda, Ng, Chi Fai, Teoh, Jeremy Yuen Chun, Laguna, Pilar, and de la Rosette, Jean

Subjects
TRANSITIONAL cell carcinoma, PROPENSITY score matching, SURVIVAL rate, OVERALL survival, PROGRESSION-free survival
Abstract

Introduction and Objective: Kidney-sparing surgery (KSS) for upper tract urothelial cancer (UTUC) has gained increasing interest recently. However, there is limited contemporary data regarding the role of KSS in ureteral urothelial carcinoma. Therefore, we investigated the survival outcomes of ureteral urothelial carcinoma after KSS from a large, prospective international UTUC registry. Methods: The Clinical Research Office of the Endourology Society-Urothelial Carcinomas of the Upper Tract (CROES-UTUC) Registry included patients with UTUC who received KSS or radical nephroureterectomy (RNU) between 2014 and 2019. In this study, we included patients with ureteral UTUC only. Study outcomes included overall survival (OS), cancer-specific survival (CSS), upper tract recurrence-free survival (RFS), intravesical RFS, progression-free survival (PFS), and metastasis-free survival (MFS). Propensity score matching (PSM) was performed to balance the tumor features' differences between groups. Results: Of the 391 patients with ureteral UTUC, 309 (79.0%) received RNU and 82 (21.0%) received KSS by ureteroscopy with laser ablation (n = 28) or segmental resection (n = 54). After PSM, there were no differences in OS (p = 0.525), CSS (p = 0.487), upper tract RFS (p = 0.147), intravesical RFS (p = 0.989), PFS (p = 0.617), and MFS (p = 0.336) between KSS and RNU. There were no significant differences between ureteroscopic ablation and segmental resection in OS, CSS, intravesical RFS, PFS, and MFS with RNU. Proximal ureteral UTUC had worse OS and CSS outcomes than other tumor locations following segmental resection. Conclusions: In patients with ureteral UTUC, no significant differences in long-term survival outcomes were observed between KSS and RNU. Proximal ureteral UTUC had worse survival outcomes over other tumor locations following segmental resection. [ABSTRACT FROM AUTHOR]

Published
2024
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172. High Levels of Incidental COVID-19 Infection in Emergency Urology Admissions: A Propensity Score-Matched Real World Data Analysis across Surgical Specialties.

Author

Liu, Alex Qinyang, Choy, Eric Ka-Ho, Chiu, Peter Ka-Fung, Yee, Chi-Hang, Ng, Chi-Fai, and Teoh, Jeremy Yuen-Chun

Subjects
URINARY tract infections, SURGERY, COVID-19, COVID-19 pandemic, PROPENSITY score matching
Abstract

Background: An incidental COVID-19 infection is often found in patients admitted for non-COVID-19-related conditions. This study aims to investigate the incidence of COVID-19 infections across surgical specialties including urology, general surgery, and orthopaedic surgery. Methods: This is a retrospective cohort study based on a territory-wide electronic database in Hong Kong. All emergency in-hospital admissions under the urology, general surgery, and orthopaedic surgery divisions in the public healthcare system in Hong Kong from January to September 2022 were included. All patients were routinely screened for SARS-CoV-2, based on admission protocols during the investigation period. Baseline characteristics were retrieved, with 1:1:1 propensity score matching being performed. Incidental COVID-19 rates were then compared across specialties. Results: A total of 126,034 patients were included. After propensity score matching, the baseline characteristics were well balanced, and 8535 patients in each group were analysed. Urology admission was noted to have a statistically significant higher incidence of incidental COVID-19 at 9.3%, compared to general surgery (5.4%) or orthopaedic surgery (5.6%). Amongst urology patients with incidental COVID-19 infection, 35.8% were admitted for retention of urine, 27.9% for haematuria, and 8.6% for a urinary tract infection. Conclusions: This large-scale cohort study demonstrated that incidental COVID-19 rates differ between surgical specialties, with urology having the highest proportion of incidental COVID-19 infection. [ABSTRACT FROM AUTHOR]

Published
2024
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173. Toward a Standardized Approach for Characterizing β‐Fleck Defects in Titanium Alloys.

Author

Ng, Chi‐Ho, Bermingham, Michael, Collins, Peter, and Dargusch, Matthew

Subjects
HEAT treatment, IMPACT (Mechanics), SERVICE life, IMAGE analysis, LOW temperatures
Abstract

β‐flecks are a type of segregation defect commonly encountered during the solidification of titanium alloys enriched with β‐stabilizing elements. These defects are associated with a detrimental impact on mechanical properties, which potentially limit the service life of parts containing them. Despite their significance, a standardized method for identifying these defects is lacking. In this study, a systematic approach is provided to detecting and characterizing β‐flecks in a representative metastable β‐Ti alloy and β‐C (ASTM Grade 19/Ti–3Al–8V–6Cr–4Mo–4Zr). By combining low temperature but prolonged aging, time‐dependent etching, and Fiji‐assisted image analysis, the presence and characteristics of β‐flecks are determined with precision and impartiality. This straightforward technique offers a reliable means for visualizing and quantifying β‐flecks in titanium alloys. It establishes a foundational framework that can be broadly applied to various β‐Ti alloys prone to β‐fleck formation. [ABSTRACT FROM AUTHOR]

Published
2024
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176. An International Collaborative Consensus Statement on En Bloc Resection of Bladder Tumour Incorporating Two Systematic Reviews, a Two-round Delphi Survey, and a Consensus Meeting

Author

Teoh, Jeremy Yuen-Chun, MacLennan, Steven, Chan, Vinson Wai-Shun, Miki, Jun, Lee, Hsiang-Ying, Chiong, Edmund, Lee, Lui-Shiong, Wei, Yong, Yuan, Yuhong, Yu, Chun-Pong, Chow, Wing-Kie, Poon, Darren Ming-Chun, Chan, Ronald, Lai, Fernand, Ng, Chi-Fai, Breda, Alberto, Kramer, Mario Wolfgang, Malavaud, Bernard, Mostafid, Hugh, Herrmann, Thomas, and Babjuk, Marek

Published
2020
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179. A Global Survey on the Impact of COVID-19 on Urological Services

Author

Teoh, Jeremy Yuen-Chun, Ong, William Lay Keat, Gonzalez-Padilla, Daniel, Castellani, Daniele, Dubin, Justin M., Esperto, Francesco, Campi, Riccardo, Gudaru, Kalyan, Talwar, Ruchika, Okhunov, Zhamshid, Ng, Chi-Fai, Jain, Nitesh, Gauhar, Vineet, Wong, Martin Chi-Sang, Wroclawski, Marcelo Langer, Tanidir, Yiloren, Rivas, Juan Gomez, Tiong, Ho-Yee, and Loeb, Stacy

Published
2020
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183. Discovery of a variable energy-dependent X-ray polarization in the accreting neutron star GX 5−1

Author

Fabiani, Sergio, primary, Capitanio, Fiamma, additional, Iaria, Rosario, additional, Poutanen, Juri, additional, Gnarini, Andrea, additional, Ursini, Francesco, additional, Farinelli, Ruben, additional, Bobrikova, Anna, additional, Steiner, James F., additional, Svoboda, Jiri, additional, Anitra, Alessio, additional, Baglio, Maria C., additional, Carotenuto, Francesco, additional, Del Santo, Melania, additional, Ferrigno, Carlo, additional, Lewis, Fraser, additional, Russell, David M., additional, Russell, Thomas D., additional, van den Eijnden, Jakob, additional, Cocchi, Massimo, additional, Di Marco, Alessandro, additional, La Monaca, Fabio, additional, Liu, Kuan, additional, Rankin, John, additional, Weisskopf, Martin C., additional, Xie, Fei, additional, Bianchi, Stefano, additional, Burderi, Luciano, additional, Di Salvo, Tiziana, additional, Egron, Elise, additional, Illiano, Giulia, additional, Kaaret, Philip, additional, Matt, Giorgio, additional, Mikušincová, Romana, additional, Muleri, Fabio, additional, Papitto, Alessandro, additional, Agudo, Iván, additional, Antonelli, Lucio A., additional, Bachetti, Matteo, additional, Baldini, Luca, additional, Baumgartner, Wayne H., additional, Bellazzini, Ronaldo, additional, Bongiorno, Stephen D., additional, Bonino, Raffaella, additional, Brez, Alessandro, additional, Bucciantini, Niccolò, additional, Castellano, Simone, additional, Cavazzuti, Elisabetta, additional, Chen, Chien-Ting, additional, Ciprini, Stefano, additional, Costa, Enrico, additional, De Rosa, Alessandra, additional, Del Monte, Ettore, additional, Di Gesu, Laura, additional, Di Lalla, Niccolò, additional, Donnarumma, Immacolata, additional, Doroshenko, Victor, additional, Dovčiak, Michal, additional, Ehlert, Steven R., additional, Enoto, Teruaki, additional, Evangelista, Yuri, additional, Ferrazzoli, Riccardo, additional, Garcia, Javier A., additional, Gunji, Shuichi, additional, Hayashida, Kiyoshi, additional, Heyl, Jeremy, additional, Iwakiri, Wataru, additional, Jorstad, Svetlana G., additional, Karas, Vladimir, additional, Kislat, Fabian, additional, Kitaguchi, Takao, additional, Kolodziejczak, Jeffery J., additional, Krawczynski, Henric, additional, Latronico, Luca, additional, Liodakis, Ioannis, additional, Maldera, Simone, additional, Manfreda, Alberto, additional, Marin, Frédéric, additional, Marinucci, Andrea, additional, Marscher, Alan P., additional, Marshall, Herman L., additional, Massaro, Francesco, additional, Mitsuishi, Ikuyuki, additional, Mizuno, Tsunefumi, additional, Negro, Michela, additional, Ng, Chi-Yung, additional, O’Dell, Stephen L., additional, Omodei, Nicola, additional, Oppedisano, Chiara, additional, Pavlov, George G., additional, Peirson, Abel L., additional, Perri, Matteo, additional, Pesce-Rollins, Melissa, additional, Petrucci, Pierre-Olivier, additional, Pilia, Maura, additional, Possenti, Andrea, additional, Puccetti, Simonetta, additional, Ramsey, Brian D., additional, Ratheesh, Ajay, additional, Roberts, Oliver J., additional, Romani, Roger W., additional, Sgrò, Carmelo, additional, Slane, Patrick, additional, Soffitta, Paolo, additional, Spandre, Gloria, additional, Swartz, Douglas A., additional, Tamagawa, Toru, additional, Tavecchio, Fabrizio, additional, Taverna, Roberto, additional, Tawara, Yuzuru, additional, Tennant, Allyn F., additional, Thomas, Nicholas E., additional, Tombesi, Francesco, additional, Trois, Alessio, additional, Tsygankov, Sergey S., additional, Turolla, Roberto, additional, Vink, Jacco, additional, Wu, Kinwah, additional, and Zane, Silvia, additional

Published
2024
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186. Asia prostate cancer study (A-CaP Study) launch symposium

Author

Akaza, Hideyuki, Hirao, Yoshihiko, Kim, Choung-Soo, Oya, Mototsugu, Ozono, Seiichiro, Ye, Dingwei, Cooperberg, Matthew, Hinotsu, Shiro, Lee, Ji Youl, Zhu, Gang, Namiki, Mikio, Horie, Shigeo, Chung, Byung Ha, Chen, Chung-Hsin, Fai, Ng Chi, Hakim, Lukman, Chiong, Edmund, Letran, Jason, Umbas, Rainy, Suzuki, Kazuhiro, Nishimura, Kazuo, Ong, Teng Aik, Lojanapiwat, Bannakij, Wu, Tong-lin, Kim, Wun-Jae, Murphy, Declan, Ogawa, Osamu, Carroll, Peter, Naito, Seiji, and Tsukamoto, Taiji

Subjects
Biomedical and Clinical Sciences, Clinical Sciences, Oncology and Carcinogenesis, Prostate Cancer, Urologic Diseases, Cancer, Aging, Asian Cancer, Database, Prospective Study, Clinical sciences, Oncology and carcinogenesis
Abstract

The Asian Prostate Cancer (A-CaP) Study is an Asia-wide initiative that has been developed over the course of 2 years. The A-CaP Study is scheduled to begin in 2016, when each participating country or region will begin registration of newly diagnosed prostate cancer patients and conduct prognosis investigations. From the data gathered, common research themes will be identified, such as comparisons among Asian countries of background factors in newly diagnosed prostate cancer patients. This is the first Asia-wide study of prostate cancer and has developed from single country research efforts in this field, including in Japan and Korea. The inaugural Board Meeting of A-CaP was held on December 11, 2015 at the Research Center for Advanced Science and Technology, The University of Tokyo, attended by representatives of all participating countries and regions, who signed a memorandum of understanding concerning registration for A-CaP. Following the Board Meeting an A-CaP Launch Symposium was held. The symposium was attended by representatives of countries and regions participating in A-CaP, who gave presentations. Presentations and a keynote address were also delivered by representatives of the University of California San Francisco, USA, and the Peter MacCallum Cancer Centre, Australia, who provided insight and experience on similar databases compiled in their respective countries.

Published
2016

187. Berkovich spectra of elements in Banach Rings

Author

Leung, Chi-Wai and Ng, Chi-Keung

Subjects
Mathematics - Functional Analysis, Mathematics - Commutative Algebra, Mathematics - Number Theory, Mathematics - Rings and Algebras, Mathematics - Spectral Theory, 46H99
Abstract

Adapting the notion of the spectrum $\Sigma_a$ for an element $a$ in an ultrametric Banach algebra (as defined by Berkovich), we introduce and briefly study the Berkovich spectrum $\sigma^{Ber}_R(u)$ of an element $u$ in a Banach ring $R$. This spectrum is a compact subset of the affine analytic space $A_Z^1$ over $Z$, and the later can be identified with the "equivalence classes" of all elements in all complete valuation fields. If $R$ is generated by $u$ as a unital Banach ring, then $\sigma^{Ber}_R(u)$ coincides with the spectrum of $R$ (as defined by Berkovich). If $R$ is a unital complex Banach algebra, then $\sigma^{Ber}_R(u)$ is the "folding up" of the usual spectrum $\sigma_B(u)$ alone the real axis. For a non-Archimedean complete valuation field $k$ and an infinite dimensional ultrametric $k$-Banach space $E$ with an orthogonal base, if $u\in L(E)$ is a completely continuous operator, we show that many different ways to define the spectrum of $u$ give the same compact set $\sigma^{Ber}_{L(E)}(u)$. As an application, we give a lower bound for the valuations of the zeros of the Fredholm determinant $\det(1- t\cdot u)$ (as defined by Serre) in complete valuation field extensions of $k$. Using this, we give a concrete example of a completely continuous operator whose Fredholm determinant does not have any zero in any complete valuation field extension of $k$., Comment: 28pages; 1 figures; any comment is welcome

Published
2014

188. Model comparison with composite likelihood information criteria

Author

Ng, Chi Tim and Joe, Harry

Subjects
Mathematics - Statistics Theory
Abstract

Comparisons are made for the amount of agreement of the composite likelihood information criteria and their full likelihood counterparts when making decisions among the fits of different models, and some properties of penalty term for composite likelihood information criteria are obtained. Asymptotic theory is given for the case when a simpler model is nested within a bigger model, and the bigger model approaches the simpler model under a sequence of local alternatives. Composite likelihood can more or less frequently choose the bigger model, depending on the direction of local alternatives; in the former case, composite likelihood has more "power" to choose the bigger model. The behaviors of the information criteria are illustrated via theory and simulation examples of the Gaussian linear mixed-effects model., Comment: Published in at http://dx.doi.org/10.3150/13-BEJ539 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm)

Published
2014
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194. Can Co-Curricular Activities Enhance the Learning Effectiveness of Students?: An Application to the Sub-Degree Students in Hong Kong

Author

Leung, Chi-Hung, Ng, Chi Wing Raymond, and Chan, Po On Ella

Abstract

A total of 575 students from the Associate Degree Foundation Program and the Associate Degree Program participated in this study. The two purposes of this study were to use the time series between/within experimental design to examine whether participation in co-curricular activities could (1) enhance student learning effectiveness and (2) have positive effects on the academic performance of self-funded sub-degree students in Hong Kong. It was found that participation in co-curricular activities could not enhance student learning effectiveness. Associate degree students were too preoccupied by the need to attain good academic results in the first 2-3 terms of study. Rather, this study suggests that student learning effectiveness is affected by the time factor. High learning effectiveness was observed in the middle of the academic year but relatively low learning effectiveness at the end of the year. (Contains 5 footnotes and 6 tables.)

Published
2011

196. A 2-year prospective evaluation of the Prostate Health Index in guiding biopsy decisions in a large cohort

Author

Chiu, Peter Ka-Fung, Liu, Alex Qinyang, Lau, Sui-Yan, Teoh, Jeremy Yuen-Chun, Ho, Chi-Chun, Yee, Chi-Hang, Hou, See-Ming, Chan, Chi-Kwok, Tang, Wai-Lun, Bangma, Chris H., Chu, Peggy Sau-Kwan, Poon, Wing-Tat, Ng, Chi-Fai, Roobol, Monique J., Chiu, Peter Ka-Fung, Liu, Alex Qinyang, Lau, Sui-Yan, Teoh, Jeremy Yuen-Chun, Ho, Chi-Chun, Yee, Chi-Hang, Hou, See-Ming, Chan, Chi-Kwok, Tang, Wai-Lun, Bangma, Chris H., Chu, Peggy Sau-Kwan, Poon, Wing-Tat, Ng, Chi-Fai, and Roobol, Monique J.

Abstract

Objectives: To prospectively evaluate how the Prostate Health Index (PHI) impacts on clinical decision in a real-life setting for men with a prostate-specific antigen (PSA) level between 4 and 10 ng/mL and normal digital rectal examination. Patients and Methods: Since 2016, the PHI has been available at no cost to eligible men in all Hong Kong public hospitals. All eligible patients who received PHI testing in all public Urology units (n = 16) in Hong Kong between May 2016 and August 2017 were prospectively included and followed up. All included men had a PHI test, with its result and implications explained; the subsequent follow-up plan was then decided via shared decision-making with urologists. Patients were followed up for 2 years, with outcomes including prostate biopsy rates and biopsy findings analysed in relation to the initial PHI measurements. Results: A total of 2828 patients were followed up for 2 years. The majority (82%) had PHI results in the lower risk range (score <35). Knowing the PHI findings, 83% of the patients with elevated PSA decided not to undergo biopsy. In all, 11% and 45% opted for biopsy in the PHI score <35 and ≥35 groups, respectively. The initial detection rate of International Society of Urological Pathology (ISUP) Grade Group (GG) ≥2 cancer was higher in the PHI score ≥35 group (23%) than in the PHI score <35 group (7.9%). Amongst patients with no initial positive biopsy findings, the subsequent positive biopsy rate for ISUP GG ≥2 cancer was higher in the PHI score ≥35 group (34%) than the PHI score <35 group (13%) with a median follow-up of 2.4 years. Conclusion: In a real-life setting, with the PHI incorporated into the routine clinical pathway, 83% of the patients with elevated PSA level decided not to undergo prostate biopsy. The PHI pathway also improved the high-grade prostate cancer detection rate when compared to PSA-driven strategies. Higher baseline PHI predicted subsequent biopsy outcome at 2 years. The PHI

Published
2024

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