Optimal Reserve Prices in Sequential Auctions with Imperfect Commitment

In a sequential auction of perfect substitutes, we analyze the consequences of the seller's incapacity to commit perfectly to a reserve-price schedule. When facing such a seller, the bidders have strong incentives not to reveal during the earlier rounds of the auction any information about their valuations. If the seller observes only the winning bid in each round, as in a sequence of Dutch auctions, there is a symmetric monotone equilibrium in which the seller may lower the reserve price over time. The possibility of lower future reserve prices makes several bidder types abstain from the earlier rounds, even though their valuations exceed the requested price. In addition, because of the restriction in competition, the participating bidders shade their bids sharply. Thus, imperfect commitment results in revenue loss. The loss becomes more severe if the seller attempts to suppress some of the information revealed in the auction, for example, by learning only whether an item is sold. Finally, if the seller observes all bids, as in a sequence of sealed-bid auctions, a monotone equilibrium fails to exist, however small the imperfection of the seller's commitment is. Our results rationalize the adoption of costly commitment or privacy preserving measures, such as the use of a well established auction house

Three Essays on Sequential Auctions

This dissertation examines the reasons for which a seller may decide to conduct a multi-unit auction sequentially rather than simultaneously. It analyzes the manner in which the information generated during a sequential auction can affect bidding to the seller's benefit and demonstrates the requirement of intertemporal commitment to the auction rules.When the seller cannot commit not to alter the reserve price over time, the bidders are reluctant to reveal their valuations. Therefore, with single-unit demands, a symmetric monotone equilibrium exists only in a sequential Dutch auction. In the earlier rounds of this auction, because of the anticipation of lower reserve prices in the future, some buyers prefer not to submit a bid, although their valuations exceed the requested reserve price. Furthermore, any buyer submitting a bid shades it sharply. Consequently, under imperfect commitment, the optimal sequential auction results in lower expected revenue than its simultaneous counterpart.In the presence of allocative and informational externalities, in particular, in a sale of two oligopoly licenses, a sequential auction succeeds in eliminating some of the payoff uncertainty by allocating the licenses in an ordered manner, according to the bidders' strength. Therefore, the weaker oligopolist can acquire his license at a lower price than the one he would pay in a simultaneous auction. In addition, he can avoid overpaying. Conversely, the stronger oligopolist pays a higher price, so that, when the bidders' production costs are independent, the two auction schemes generate the same expected revenue. Therefore, without affecting the seller's revenue or efficiency objectives, the sequential auction results in a more equal distribution of the wealth generated by the oligopoly.Finally, when the preparation or submission of bids is costly, so that a buyer will not enter the auction unless he expects a substantial gain from it, low prices in the earlier rounds of a sequential sale trigger stronger participation, and, consequently, higher prices in the later rounds. A sequential auction, therefore, may result in higher expected revenue than a simultaneous sale, especially when the number of potential bidders is large, the participation cost small, or the distribution of valuations convex

Long-Term Oxygen Therapy in COPD: Factors Affecting and Ways of Improving Patient Compliance

Long-term oxygen therapy (LTOT) is the cornerstone mode of treatment in patients with severe chronic obstructive pulmonary disease (COPD) associated with resting hypoxaemia. When appropriately prescribed and correctly used, LTOT has clearly been shown to improve survival in hypoxemic COPD patients. Adherence to LTOT ranges from 45% to 70% and utilization for more than 15 hours per day is widely accepted as efficacious. Although several studies have addressed the level of patients' adherence to LTOT, few have suggested or evaluated interventions that conduce to compliance enhancement. The lack of sufficient data regarding COPD patients following oxygen prescription is an enormous void that must be duly confronted to augment clinical effectiveness and cost containment for the long term use. The present review article highlights factors influencing the compliance of patients using LTOT and emphasizes novel strategies and interventions that may prove to be of significant benefit given the remarkably little current research appraising this issue. Therefore, additional research should be promptly performed to verify the efficacy of newly designed approaches in improving the outcomes of patients receiving LTOT

The effects of rivalry on scientific progress under public vs private learning

We offer a model of scientific progress in which uncertainty resolves over time. We show that rivalry leads to less experimentation, extending results for preemption games to experimentation with uncertain outcomes. We compare experimentation duration and welfare when experimental outcomes are publicly versus privately observable. We show that public learning can generate more experimentation and higher welfare when uncertainty about the feasibility of a breakthrough is large; breakthroughs are rare even when they are feasible; and experiments produce results infrequently. Our results shed light on recent criticism of the science system

Right-sided Bochdalek Hernia Presenting as a Solitary Pulmonary Nodule

AbstractBochdalek hernia is a well-known disorder, which represents visceral herniation through a posterior diaphragmatic defect. In this report we present an adult man with a right-sided Bochdalek hernia mimicking a solitary pulmonary nodule. Furthermore, we perform a brief review of the literature, with emphasis on novel imaging techniques that establish the diagnosis. In conclusion, Bochdalek hernia should be considered in the differential diagnosis of a posterior diaphragmatic or paraspinal opacity. Correct diagnosis is of paramount importance and can be easily established by non-invasive imaging techniques

Recurrent Respiratory Papillomatosis: A Rare Chronic Disease, Difficult to Treat, with Potential to Lung Cancer Transformation: Apropos of Two Cases and a Brief Literature Review

Recurrent respiratory papillomatosis (RRP), which is caused exclusively by human papilloma virus (HPV), is a rare condition characterized by recurrent growth of benign papillomata in the respiratory tract. The papillomata can occur anywhere in the aerodigestive tract but most frequently in the larynx, affecting both children and adults. The management of this entity remains still challenging since no specific definitive treatment exists. Nevertheless, novel surgical interventions as well as several adjuvant therapies have shown promising results in the long-term palliative management of this debilitating disease. Despite its mostly benign nature, RRP may cause significant morbidity and mortality because of its unpredictable clinical course and especially its tendency, albeit infrequent, for malignant transformation. In this article, we present two patients with RRP; one underwent bronchoscopic laser ablation in combination with inhaled interferon-alpha administration that led to a long-term regression of the disease while the other patient was diagnosed with transformation to squamous cell lung carcinoma with fatal outcome. We include a review of the current literature with special emphasis on RRP management and the potential role of HPV in the development of lung cancer

Intramedullary thoracic spinal metastasis from small-cell lung cancer

Intramedullary thoracic spinal metastasis from small-cell lung cancer. S. Katsenos, M. Nikolopoulou. Lung cancer with intramedullary spinal cord metastasis (ISCM) is a rare event exhibiting dismal prognosis. In the present paper, we describe a 74-year-old male who developed bilateral leg weakness with associated backache and non-productive cough. Chest imaging evaluation demonstrated pronounced bilateral mediastinal lymphadenopathy and a nodular opacity in the right lower lobe. The patient was diagnosed with small cell lung cancer through bronchoscopic procedures. Magnetic resonance imaging of the spinal cord with contrast-enhancement revealed an intramedullary lesion consistent with metastasis at the T5-T6 level. Despite chemotherapy and thoracic spine radiotherapy, he eventually succumbed to the disease 3 months after diagnosis. A brief overview of the current literature is also provided laying emphasis on the therapeutic strategies of this unusual extrathoracic metastatic disease

The Challenging Evaluation of Patients with Severe Psoriasis for Latent Tuberculosis: An Important Indication for IGRA

It is well-established that tumour necrosis factor (TNF)-α-antagonist regimens are advisable for the control of moderate to severe psoriasis; however the application of these agents is associated with increased risk of TB reactivation. Screening for latent tuberculosis infection (LTBI) is indispensable prior to treatment inception in order to diminish the risk of active TB. Although tuberculin skin test (TST) still represents a useful tool for LTBI detection, it is difficult to be performed and read in patients with extensive psoriatic lesions. In this paper, we report the case of a 65-year-old male with severe psoriasis, who was evaluated by an interferon-gamma release assay (IGRA) for LTBI diagnosis prior to anti-TNF-α therapy. Furthermore, the physiological aspects of interferon-gamma release assays are discussed emphasizing the value of these novel immunodiagnostic tests (IGRAs) for presumable LTBI in all patients with extensive skin disorders

Chronic eosinophilic pneumonia associated with neurofibromatosis type 1 : an unusual complication

Neurofibromatosis type 1 (formerly known as von Recklinghausen’s disease) is an autosomal dominant disorder, which results from the proliferation of the neural crest cells, thus affecting any organ system. Several pulmonary manifestations have hitherto been reported, including chest wall deformities, diffuse lung disease, thoracic neoplasms, pulmonary arterial hypertension, central hypoventilation, diaphragmatic paralysis and meningocele. However, eosinophilic lung disorders have not been described. An unusual case of chronic eosinophilic pneumonia in a patient with neurofibromatosis type 1, is reported herein. He had a propitious outcome, following corticosteroid treatment. This is the first well-documented case of chronic eosinophilic pneumonia and neurofibromatosis type 1 in the same patient. These clinical entities might share common pathogenic mechanisms, as suggested by the present study, that could explain their co-existence