Principal Components Analysis in implied volatility modeling (Analiza skladowych glownych w modelowaniu implikowanej zmiennosci)

We analyze the implied volatility surface structure of ODAX options as traded on DTB (currently Eurex). We apply PCA to cross sections of the implied volatility surface taken along the same moneyness (m) or the same time to maturity (T). For data from the period October 3rd 1997 – November 30th 1998 a substantial reduction of the dimensionality of the problem was achieved. It turned out that (i) for the m-sections the first two principal components contained 99.997% of information, and (ii) for the T-sections the first three principal components contained 99.892% of information. Moreover, the obtained principal components were very similar for different m's or T's allowing us to assume that that the space spanned by the eigenvectors is identical across several groups (of m's or T's), i.e. leading us to the so called Common PCA.Volatility surface; ODAX option; Principal Component Analysis; Common PCA;

Intracerebral electroencephalography in targeting anterior thalamic nucleus for deep brain stimulation in refractory epilepsy

Background Results of DBS of ATN in refractory epilepsy depend on accuracy of the electrode's location. We searched for characteristic intraoperative, intracerebral EEG recording pattern from anterior thalamic nuclei (ATNs) as a biological marker for verifying the electrode's position. Methods There were six patients with refractory epilepsy scheduled for deep brain stimulation (DBS) procedure. At surgery, to map the target, we recorded EEG from each lead of DBS electrodes. One patient underwent a 24 hours EEG with continuous recording from both ATNs before internalization of stimulator units. Results In all patients we recorded spontaneous bioelectric activity of ATNs. The pattern of the recording from the ATN was similar in all cases. In the one patient where 24-hour recording was done with simultaneous scalp EEG, a complex partial seizure was captured. Conclusion This is the first report of using DBS electrode for intraoperative EEG recordings from the ATN in patients with refractory epilepsy. Since we managed to find the characteristic pattern of bioelectric activity of ATN, this technique seems to be a promising method for targeting this structure during the operation

Intracranial video-EEG monitoring in presurgical evaluation of patients with refractory epilepsy

Objective Reviewing our experience in intracranial video-EEG monitoring in the presurgical evaluation of patients with refractory epilepsy. Methods We report on 62 out of 202 (31%) patients with refractory epilepsy, who underwent a long term video-EEG monitoring (LTM). The epileptogenic zone (EZ) was localised either based on the results of LTM or after intracranial EEG recordings from depth, subdural or foramen ovale electrodes. The decision on the location of the electrodes was based upon semiology of the seizures, EEG findings and the lesions visualised in MRI brain scan. Intraoperative corticography was carried out before and right after the resection of the seizure onset zone. Results The video-EEG monitoring could localise EZ in 43 (69%) cases based. The remaining patients underwent invasive diagnostics: 10 (53%) had intracerebral depth electrodes, 6 (31%) depth and subdural and 3 (16%) foramen ovale electrodes. Intracranial video EEG recordings showed seizure focus in all the patients. Ten of them had EZ in mesial temporal structures, 4 in accessory motor area, 3 at the base of the frontal lobe and 2 in parietal lobe. There was one case of an asymptomatic intracerebral haematoma at the electrode. All patients were subsequently operated on. In 15 (79%) cases the seizures subsided (follow-up from 2 to 5 years), in 4 (21%) they decreased. Conclusions The intracranial EEG is required in all patients with normal MRI (so-called nonlesional cases) in whom EZ is suspected to be located in the hippocampus, insula or in the basal parts of the frontal lobe

Fournier's gangrene – a clinical case report

Fournier’s gangrene is an acute, rapidly progressive, necrotizing infection of the skin and subcutaneous tissues surrounding the genitals and perineum. Necrotizing fasciitis of the genital area is a rare disease entity. Although it concerns mostly males, can also occur in females and adolescents. In this syndrome, bacteria produce gases which accumulate in the infected tissue. The damage may also comprise tissue of the penis and scrotum. The infection is caused by aerobic and anaerobic bacteria. Usually the Fournier’s gangrene is caused by Staphylococci, Streptococci and Enteric bacteria. Bacterial infection can accompany the fungal infection. The high mortality rate is associated with bacterial contagion of the skin, fat, fascia and blood vessels. Harmful enzymes, produced by micro-organisms, induce numerous blood clots. They can lead to ischemia, which contribute to the development of necrosis. Fournier’s syndrome is a disease with a high mortality rate. Immunodeficiency, diabetes and chronic alcohol abuse favor the development of gangrene. Abrasion, burn or surgery complication may be the route of infection for microorganisms. Clinical symptoms appear within few days. Diagnostic process is based on the clinical picture. It is crucial to start treatment as soon as possible. Delay of the wide spectral intravenous antibiotic therapy and surgical removal of the necrotic tissue may result in death of the patient

Joint flow-seismic inversion for characterizing fractured reservoirs: theoretical approach and numerical modeling

Traditionally, seismic interpretation is performed without any account of the flow behavior. Here, we present a methodology to characterize fractured geologic media by integrating flow and seismic data. The key element of the proposed approach is the identification of the intimate relation between acoustic and flow responses of a fractured reservoir through the fracture compliance. By means of synthetic models, we show that: (1) owing to the strong (but highly uncertain) dependence of fracture permeability on fracture compliance, the modeled flow response in a fractured reservoir is highly sensitive to the geophysical interpretation; and (2) by incorporating flow data (well pressures and production curves) into the inversion workflow, we can simultaneously reduce the error in the seismic interpretation and improve predictions of the reservoir flow dynamics.Eni-MIT Energy Initiative Founding Member Progra

The most common etiological factors of conjunctivitis

Conjunctivitis is one of the most common diseases of the anterior segment. It is characterized by redness of the eye, conjunctivital injection, the presence of secretions in the conjunctival sac. The most common symptoms reported by patients include: pain, redness, itching, foreign body sensation and photophobia. Intensifying severe symptoms can lead to difficulties in daily activities. The correct diagnosis of the etiological agent is essential to implement an appropriate treatment and relieve symptoms of the disease

Reservoir characterization in an underground gas storage field using joint inversion of flow and geodetic data

Characterization of reservoir properties like porosity and permeability in reservoir models typically relies on history matching of production data, well pressure data, and possibly other fluid-dynamical data. Calibrated (history-matched) reservoir models are then used for forecasting production and designing effective strategies for improved oil and gas recovery. Here, we perform assimilation of both flow and deformation data for joint inversion of reservoir properties. Given the coupled nature of subsurface flow and deformation processes, joint inversion requires efficient simulation tools of coupled reservoir flow and mechanical deformation. We apply our coupled simulation tool to a real underground gas storage field in Italy. We simulate the initial gas production period and several decades of seasonal natural gas storage and production. We perform a probabilistic estimation of rock properties by joint inversion of ground deformation data from geodetic measurements and fluid flow data from wells. Using an efficient implementation of the ensemble smoother as the estimator and our coupled multiphase flow and geomechanics simulator as the forward model, we show that incorporating deformation data leads to a significant reduction of uncertainty in the prior distributions of rock properties such as porosity, permeability, and pore compressibility.Eni S.p.A. (Firm

Male breast hypertrophy - a review of modern methods of treatment

Gynecomastia is a benign enlargement of the mammary gland in males. Nowadays it is a common disorder of all ages, including newborns, adolescents and adults. It may be bilateral or unilateral enlargement of the breast. Gynecomastia may be a severe problem in adolescents resulting in development of psychological disorders. Evolution of surgical treatment options, depending on the degree of breast hypertrophy advancement, brought significant improvement in aesthetic effect and patient’s quality of life. This paper presents the development of pharmaceutical and surgical treatment technics. The manuscript proposes the optimal methods of clinical approach to the patients with an enlargement of the breast

Sequential approach to joint flow-seismic inversion for improved characterization of fractured media

Seismic interpretation of subsurface structures is traditionally performed without any account of flow behavior. Here we present a methodology for characterizing fractured geologic reservoirs by integrating flow and seismic data. The key element of the proposed approach is the identification—within the inversion—of the intimate relation between fracture compliance and fracture transmissivity, which determine the acoustic and flow responses of a fractured reservoir, respectively. Owing to the strong (but highly uncertain) dependence of fracture transmissivity on fracture compliance, the modeled flow response in a fractured reservoir is highly sensitive to the geophysical interpretation. By means of synthetic models, we show that by incorporating flow data (well pressures and tracer breakthrough curves) into the inversion workflow, we can simultaneously reduce the error in the seismic interpretation and improve predictions of the reservoir flow dynamics. While the inversion results are robust with respect to noise in the data for this synthetic example, the applicability of the methodology remains to be tested for more complex synthetic models and field cases.Eni-MIT Energy Initiative Founding Member ProgramKorea (South). Ministry of Land, Transportation and Maritime Affairs (15AWMP-B066761-03