Cartel Mechanism Design: Nonratifiable Conditions of Collusive Behavior

This dissertation is about an open question of cartel ratifiable conditions. My research goal is to establish a mechanism which is able to detect and explain cartels' activities. My research question in the second chapter is whether or not an efficient cartel mechanism is ratifiable in the first-price sealed-bid auction format with participation costs. R. McAfee and J. McMillan study the coordinated bidding strategies in a strong cartel, which is incentive-compatible and efficient. This chapter investigates this efficient collusive mechanism with two important conditions (1) bidders can update their information through a cartel's prior auction and (2) they have to pay participation costs to participate in seller's auction. The concept of ratifiability, introduced by P. Cramton and T. Palfrey, is applied to explore the first-price sealedbid auction with participation costs. I discovered that the efficient cartel mechanism, such as pre-auction knockout, would be ratified when either of the two conditions exists. However, this mechanism is no longer ratifiable when both conditions exist. The bidder with the highest value in the cartel would have incentive to betray, since doing so sends a credible signal of high value. Hence, the other bidders will be discouraged from participating in the seller's auction and the highest-value bidder maximizes his revenue. In the third chapter, I studied the seller's strategy when she faces a cartel in an auction mechanism. An active seller's optimal strategy is to raise the reserve price to a level that is higher than her own valuation. The collusive mechanism is sustainable even though its revenue is extracted by the higher reserve price. If the seller is authorized to change the auction mechanism, she can receive the expected payoff, prevent the formation of a ring and keep the auction efficient. Further, I presented two methods that could deter a cartel under specific conditions. One is the residual claimants method as proposed by Y. Che and J. Kim and the other is to set a positive participation cost as outlined in the first chapter. The residual claimants method can inhibit a ring in many cases, but it may have some trouble in preventing an efficient cartel mechanism when there is only one participant in the seller's auction. In the fourth chapter, I investigated how to achieve external efficiency in a repeated game. In particular, I looked into the allocation of the budgeted that allows an authority, such as the government, to differentiate collusive behavior and to expose agents to external threats. A threshold level of the budget payment is found in an incentive compatible collusive mechanism for which the government can prevent an agent from participating. In a two-stage model, I showed that if the government can boost exemption or have more budget to subsidize agents, it is less likely that a ring will be formed

Nonratifiability of the Cartel Mechanism in First-Price Sealed-Bid Auction with Participation Costs

McAfee and McMillan (1992) investigate the coordinated biding strategies in a strong cartel, in which the cartel members can exclude new entrants and can make transfer payments, and show that the strong cartel mechanism is incentive-compatible and efficient. In this paper however, we show the strong cartel mechanism is no longer ratifiable in the presence of participation cost, in which case the bidder with the highest value in the cartel would have incentive to veto for the collusive mechanism. This behavior could make the maximum benefit for the winning bidder

On Ratifiability of Efficient Cartel Mechanisms in First-Price Auctions with Participation Costs and Information Leakage

This paper investigates whether an efficient all-inclusive cartel mechanism studied by McAfee and McMillan (1992) can still preserve its efficiency when bidders can update their information through the cartel’s collusive mechanism and there is a cost to participate in the seller’s auction within the independent private values setting. It is shown that, when the seller uses the first-price auction, the usual efficient cartel mechanisms will no longer be ratifiable in the presence of both participation costs and potential information leakage. The bidder with the highest value in the cartel will have incentive to betray, sending a credible signal of his high value and thus discouraging other bidders from participating in the seller’s auction. However, the cartel mechanisms would still be efficient if either participation cost or information leakage, but not both, is present

On Ratifiability of Efficient Cartel Mechanisms in First-Price Auctions with Participation Costs and Information Leakage

This paper investigates whether an efficient all-inclusive cartel mechanism studied by McAfee and McMillan (1992) can still preserve its efficiency when bidders can update their information through the cartel’s collusive mechanism and there is a cost to participate in the seller’s auction within the independent private values setting. It is shown that, when the seller uses the first-price auction, the usual efficient cartel mechanisms will no longer be ratifiable in the presence of both participation costs and potential information leakage. The bidder with the highest value in the cartel will have incentive to betray, sending a credible signal of his high value and thus discouraging other bidders from participating in the seller’s auction. However, the cartel mechanisms would still be efficient if either participation cost or information leakage, but not both, is present

Happiness or hopelessness in late life: A cluster RCT of the 3L-Mind-Training programme among the institutionalized older people.

AIM(#br)To explore the effectiveness of a new mental health promotion activities program by including the criterion variables of happiness and depressive mood.(#br)DESIGN(#br)A double-blinded, clustered, randomized and controlled trial.(#br)METHOD(#br)A list of older residents was provided by the senior social worker at a geriatric institution. The participant inclusion criteria were living on one of four different floors that had separate and noninterfering spaces and having comparable disabilities. The researchers randomly selected residents on two floors as members of the intervention group; the other residents were considered the control group. The intervention groups attended 6 weeks of the 3L-Mind-Training program, whereas the control group only engaged in regular health promotion activities. The mini version of the Chinese Happiness Inventory was adapted to measure happiness. The Geriatric Depression Scale short-form was used to measure depression in older people. The generalized estimating equation was used to analyze the short-term and durative effects.(#br)FINDINGS(#br)The 126 residents ranged in age from 65-97 years old and 90% of the residents relied on wheelchairs. The intervention activities provided significant immediate and durative effects both on subjective well-being enhancement and depressive mood relief. When evaluating the overall intervention activity, 93.8% of the aged residents indicated that this program was helpful and allowed them to view life events positively.(#br)CONCLUSION AND IMPACT(#br)A well-planned mind-training program could help older people reform their viewpoint and create a more fun and happy experience of ageing.(#br)TRIAL REGISTRATION(#br)Data came from the project, initiated in 2014, which was funded by the Ministry of Science and Technology in Taiwan and was approved by the Institutional Review Board in Chung Shan Medical University (No. CS15009). The trial registration number of the study was No. ChiCTR1900021811. This article is protected by copyright. All rights reserved

The Transcription Factor Sfp1 Regulates the Oxidative Stress Response in Candida albicans

Candida albicans is a commensal that inhabits the skin and mucous membranes of humans. Because of the increasing immunocompromised population and the limited classes of antifungal drugs available, C. albicans has emerged as an important opportunistic pathogen with high mortality rates. During infection and therapy, C. albicans frequently encounters immune cells and antifungal drugs, many of which exert their antimicrobial activity by inducing the production of reactive oxygen species (ROS). Therefore, antioxidative capacity is important for the survival and pathogenesis of C. albicans. In this study, we characterized the roles of the zinc finger transcription factor Sfp1 in the oxidative stress response against C. albicans. A sfp1-deleted mutant was more resistant to oxidants and macrophage killing than wild-type C. albicans and processed an active oxidative stress response with the phosphorylation of the mitogen-activated protein kinase (MAPK) Hog1 and high CAP1 expression. Moreover, the sfp1-deleted mutant exhibited high expression levels of antioxidant genes in response to oxidative stress, resulting in a higher total antioxidant capacity, glutathione content, and glutathione peroxidase and superoxide dismutase enzyme activity than the wild-type C. albicans. Finally, the sfp1-deleted mutant was resistant to macrophage killing and ROS-generating antifungal drugs. Together, our findings provide a new understanding of the complex regulatory machinery in the C. albicans oxidative stress response

Palatal hybrid surgery for obstructive sleep apnea-state-of-the-art annotation of uvulopalatopharyngoplasty

Background: Surgery for obstructive sleep apnea (OSA) has changed in concept and technique that transformed from radical excision to functional reconstruction. The aim of this study was to investigate the safety and effectiveness of palatal hybrid surgery in OSA patients. Methods: Palatal hybrid surgery is a tissue-specific technique (mucosa-preservation, tonsil-excision, fat-ablation, muscle-relocation/suspension) used in treating OSA patients with velopharyngeal obstruction. The study included 46 consecutive adults OSA patients. The palatal hybrid surgery annotates uvulopalatopharyngoplasty in stereoscopic reconstruction of tonsillar fossa (pharyngoplasty), omni-suspension of the soft palate (palatoplasty) and advancement of uvula (uvuloplasty). Results: No patient experienced airway compromise, voice change or persistent nasal regurgitation following palatal hybrid surgery. One patient existed postoperative tonsillar fossa bleeding received conservative treatment. Postoperative pain in visual analogue scale (VAS) showed average score of 3, 3, 2, 0 at the 1st, 3rd, 7th, 14th day, respectively. Perioperative snoring severity (VAS) (8.7 vs 2.6) and daytime sleepiness (Epworth Sleepiness Scale) (11.3 vs 5.5) all improved significantly (p < 0.001). Posterior air space in retropalatal area increased from 8.4 to 11.1 mm (p < 0.001). Home sleep test showed that apnea–hypopnea index significantly reduced from 41.8 to 18.2 event/h and minimal oxygen saturation increased from 72.4 to 81.5% (p < 0.001). The success rate in individual Friedman stage was 100% (stage I), 63% (stage II) and 58% (stage III) with a total success rate of 63%. Conclusion: Palatal hybrid surgery using tissue-specific maneuver annotates UPPP in concept and technique. The results show that palatal hybrid surgery is mini-invasive with low morbid and is effective in improving subjective clinic symptoms, objective sleep parameters and success rate of OSA

Additional file 1: Figure S1. of Novel skin chamber for rat ischemic flap studies in regenerative wound repair

Detailed scale for three-layer flap chamber in different width-to-length ratio. (PPTX 535 kb

Tribbles Homolog 3 Involved in Radiation Response of Triple Negative Breast Cancer Cells by Regulating Notch1 Activation

Breast cancer is the most common cancer for women in Taiwan and post-lumpectomy radiotherapy is one of the therapeutic strategies for this malignancy. Although the 10-year overall survival of breast cancer patients is greatly improved by radiotherapy, the locoregional recurrence is around 10% and triple negative breast cancers (TNBCs) are at a high risk for relapse. The aim of this paper is to understand the mechanisms of radioresistance in breast cancers which may facilitate the development of new treatments in sensitizing breast cancer toward radiation therapy. Tribbles homolog 3 (TRIB3) is a pseudokinase protein and known to function as a protein scaffold within cells. It has been reported that higher TRIB3 expression is a poor prognostic factor in breast cancer patients with radiotherapy. In this study, we investigate the involvement of TRIB3 in the radiation response of TNBC cells. We first found that the expression of TRIB3 and the activation of Notch1, as well as Notch1 target genes, increased in two radioresistant TNBC cells. Knockdown of TRIB3 in radioresistant MDA-MB-231 TNBC cells decreased Notch1 activation, as well as the CD24-CD44⁺ cancer stem cell population, and sensitized cells toward radiation treatment. The inhibitory effects of TRIB3 knockdown in self-renewal or radioresistance could be reversed by forced expression of the Notch intracellular domain. We also observed an inhibition in cell growth and accumulated cells in the G₀/G¹ phase in radioresistant MDA-MB-231 cells after knockdown of TRIB3. With immunoprecipitation and mass spectrometry analysis, we found that, BCL2-associated transcription factor 1 (BCLAF1), BCL2 interacting protein 1 (BNIP1), or DEAD-box helicase 5 (DDX5) were the possible TRIB3 interacting proteins and immunoprecipitation data also confirmed that these proteins interacted with TRIB3 in radioresistant MDA-MB-231 cells. In conclusion, the expression of TRIB3 in radioresistant TNBC cells participated in Notch1 activation and targeted TRIB3 expression may be a strategy to sensitize TNBC cells toward radiation therapy

Tribbles Homolog 3 Involved in Radiation Response of Triple Negative Breast Cancer Cells by Regulating Notch1 Activation

Breast cancer is the most common cancer for women in Taiwan and post-lumpectomy radiotherapy is one of the therapeutic strategies for this malignancy. Although the 10-year overall survival of breast cancer patients is greatly improved by radiotherapy, the locoregional recurrence is around 10% and triple negative breast cancers (TNBCs) are at a high risk for relapse. The aim of this paper is to understand the mechanisms of radioresistance in breast cancers which may facilitate the development of new treatments in sensitizing breast cancer toward radiation therapy. Tribbles homolog 3 (TRIB3) is a pseudokinase protein and known to function as a protein scaffold within cells. It has been reported that higher TRIB3 expression is a poor prognostic factor in breast cancer patients with radiotherapy. In this study, we investigate the involvement of TRIB3 in the radiation response of TNBC cells. We first found that the expression of TRIB3 and the activation of Notch1, as well as Notch1 target genes, increased in two radioresistant TNBC cells. Knockdown of TRIB3 in radioresistant MDA-MB-231 TNBC cells decreased Notch1 activation, as well as the CD24-CD44+ cancer stem cell population, and sensitized cells toward radiation treatment. The inhibitory effects of TRIB3 knockdown in self-renewal or radioresistance could be reversed by forced expression of the Notch intracellular domain. We also observed an inhibition in cell growth and accumulated cells in the G0/G1 phase in radioresistant MDA-MB-231 cells after knockdown of TRIB3. With immunoprecipitation and mass spectrometry analysis, we found that, BCL2-associated transcription factor 1 (BCLAF1), BCL2 interacting protein 1 (BNIP1), or DEAD-box helicase 5 (DDX5) were the possible TRIB3 interacting proteins and immunoprecipitation data also confirmed that these proteins interacted with TRIB3 in radioresistant MDA-MB-231 cells. In conclusion, the expression of TRIB3 in radioresistant TNBC cells participated in Notch1 activation and targeted TRIB3 expression may be a strategy to sensitize TNBC cells toward radiation therapy