Coupling Index and Stocks

In this paper, we are interested in continuous time models in which the index level induces some feedback on the dynamics of its composing stocks. More precisely, we propose a model in which the log-returns of each stock may be decomposed into a systemic part proportional to the log-returns of the index plus an idiosyncratic part. We show that, when the number of stocks in the index is large, this model may be approximated by a local volatility model for the index and a stochastic volatility model for each stock with volatility driven by the index. This result is useful in a calibration perspective : it suggests that one should first calibrate the local volatility of the index and then calibrate the dynamics of each stock. We explain how to do so in the limiting simplified model and in the original model

Coupling Index and Stocks

In this paper, we are interested in continuous time models in which the index level induces some feedback on the dynamics of its composing stocks. More precisely, we propose a model in which the log-returns of each stock may be decomposed into a systemic part proportional to the log-returns of the index plus an idiosyncratic part. We show that, when the number of stocks in the index is large, this model may be approximated by a local volatility model for the index and a stochastic volatility model for each stock with volatility driven by the index. This result is useful in a calibration perspective : it suggests that one should first calibrate the local volatility of the index and then calibrate the dynamics of each stock. We explain how to do so in the limiting simplified model and in the original model.Index modeling, calibration, non-parametric estimation

Tuberculous flexor tenosynovitis of the hand

AbstractTuberculosis is a major public health problem in developing countries. Flexor tenosynovitis of the fingers constitutes an exceptional tuberculosis localization (Gabl et al., 1997; Senda et al., 2011) [1,2]. Unusual presentations, such as tuberculous tenosynovitis, often go undetected and are associated with a diagnostic and therapeutic delay, especially when bacteriological research proves to be negative. Here, we report a case of tuberculous flexor tenosynovitis of the hand

Teeth syndrome: diagnosis, complications and management

Teeth syndrome or fight bite is a specific entity in hand surgery that is little known. It includes infectious complications of the hand following a fist against the teeth. Neglected or misdiagnosed this injury  frequently leads to serious complications that could compromise the function of the hand. A retrospective study was performed on 20 patients treated for teeth syndrome at our department, during a period of 12  years (January 2003 to April 2015). All young adults with a mean age of 28 years and a significant male  predominance. The dominant side was involved in 15 patients. Lesions were divided into 4 cases of simple dorsal wounds facing the MP joint, 8 cases of dorsal hand cellulitis, and 8 cases of arthritis and osteoarthritis of the  metacarpophalangeal (MP) joint of the long fingers. The index was the most affected finger. Treatment  consisted in debridement of necrotic tissues, stabilization with external fixation for arthritis, skin  reconstruction was performed secondarily. Result was assessed as good in 60% of cases. Clenched fist  injuries to the mouth (teeth syndrome or fight bite) are known as being the worst human bites. Usually  treated as minor injuries, without realizing a breach of the joint capsule, a lesion of the extensor tendon, or a contamination by oral flora. Any patient with a wound near the joint of the hand and was involved in a fight, need an appropriate evaluation and a specialized treatment to avoid serious complications.Key words: Human bite, cellulitis, arthritis, finger, Hand surger

A pathological fracture of the scaphoid revealing an intraosseous ganglion cyst

Intraosseous ganglion cyst is a benign bone lesion with histological similarities to the soft tissue ganglion cyst. Its location on the short bones, including the carpal bones has rarely been reported. The radiolucent carpal lesions are usually symptom-free found incidentally on radiographs of the wrist performed for other reasons. Detecting a pathological fracture of the scaphoid revealing an intraosseous ganglion cyst is exceptional. We report the case of a 21-year-old, right-handed male, presented with a one year history of progressive right-wrist pain, worsened since a month without a history of previous trauma. Plain radiographs and CT-scan revealed a cystic lesion of the scaphoid with a pathological fracture. He was successfully treated with curettage and packing with a Zaidemberg's vascularized radial graft without recurrence at two years postoperatively.Pan African Medical Journal 2016; 2

Contribution of Statistical Tests to Sparseness-Based Blind Source Separation

International audienceWe address the problem of blind source separation in the underdetermined mixture case. Two statistical tests are proposed to reduce the number of empirical parameters involved in standard sparseness-based underdetermined blind source separation (UBSS) methods. The first test performs multisource selection of the suitable time-frequency points for source recovery and is full automatic. The second one is dedicated to autosource selection for mixing matrix estimation and requires fixing two parameters only, regardless of the instrumented SNRs. We experimentally show that the use of these tests incurs no performance loss and even improves the performance of standard weak-sparseness UBSS approaches

Transport Information Collection Protocol with clustering of information sources

We improve and validate TICP, a TCP-friendly reliable transport protocol to collect information from a large number of sources spread over the Internet . A collector machine sends probes to information sources, which respond by sending back report packets containing their information. TICP adapts the rate of probes in a way to avoid implosion at the collector and congestion in the network. To ensure smooth variation of the congestion control parameters and to probe sources behind the same bottleneck at the same time, we add to TICP a mechanism that clusters information sources. This mechanism is based upon the Global Network Positionning (GNP) Internet coordinate system. By running simulations in ns-2 over realistic network topologies, we prove that TICP with clustering of information sources has shorter collect session duration and causes less packet losses than the initial version that probes sources independently of their location