389 research outputs found
Diffusion covariation and co-jumps in bidimensional asset price processes with stochastic volatility and infinite activity Levy jumps
In this paper we consider two processes driven by diffusions and jumps. The
jump components are Levy processes and they can both have finite activity and
infinite activity. Given discrete observations we estimate the covariation
between the two diffusion parts and the co-jumps. The detection of the co-jumps
allows to gain insight in the dependence structure of the jump components and
has important applications in finance. Our estimators are based on a threshold
principle allowing to isolate the jumps. This work follows Gobbi and Mancini
(2006) where the asymptotic normality for the estimator of the covariation,
with convergence speed given by the squared root of h, was obtained when the
jump components have finite activity. Here we show that the speed is the
squared root of h only when the activity of the jump components is moderate
convolution based unit root processes a simulation approach
We propose a convolution based approach to the simulation of a modified version of a unit root process where the state variable is dependent on the innovation . The dependence structure is given by a copula function . We study by simulation the effect of a negative correlation on the properties of unit roots. We call this process C-UR(1)
O(1S), OH, and O2(b) Airglow Layer Perturbations due to AGWs and their Implied Effects on the Atmosphere
The O(1S) (green line) night airglow emission in response to atmospheric gravity wave (AGW) perturbations was simulated with a linear, one-dimensional model. The results were combined with previously modeled O2(b, 0â1) atmospheric band and OH Meinel band emission response (Liu and Swenson, 2003) to derive amplitude and phase relations among multiple airglow layers in response to gravity waves with various intrinsic parameters and damping rates (β). The simulations show that the vertical profile of the standard deviation of the perturbed green line volume emission rate (VER) has a centroid altitude that is 3 km lower and a full-width-half-maximum 2.1 km smaller than the unperturbed VER profile, similar to findings for the OH and O2(b) band layers. Relative phase differences and amplitudes of vertically propagating waves can be deduced from zenith observations of the layers. Airglow weighted responses to waves are related through a cancellation factor (CF) for both layer intensity and temperature. The vertical wavelength can be deduced from relative phase information of three airglow layers separated in altitude. The vertical flux of horizontal momentum associated with gravity waves is deduced from intrinsic wave parameters. Wave damping versus altitude is used to deduce the flux divergence and local accelerations resulting from dissipative waves. The simulations are useful in calculating wave information and wave effects on the atmosphere from multiwavelength, zenith airglow observations
Quality of life measures in Italian children with atopic dermatitis and their families
<p>Abstract</p> <p>Background</p> <p>The impact of atopic dermatitis (AD) on children's quality of life (QoL) in US and European countries is relatively well known, though rarely evaluated in the Italian population. Moreover, the association between child age and QoL has not been enough investigated, even though few studies detected a worse QoL in youngest AD children. The aim of the study was to evaluate the QoL in an Italian sample of atopic children and their families, also exploring a possible association with child age.</p> <p>Methods</p> <p>60 AD children aged between 1-12 years and their mothers completed specific QoL questionnaires (IDQoL/CDLQI, DFI) and a clinician completed a measure of AD severity (SCORAD).</p> <p>Results</p> <p>AD severity (Objective SCORAD) significantly correlated with QoL measures. Severe AD children showed higher IDQoL/CDLQI and DFI scores compared to mild and moderate AD groups (<it>P </it>= 0.006 and <it>P </it>< 0.0005, respectively), but only DFI scores differed in these last two conditions (<it>P </it>= 0.014). DFI scores negatively correlated with children's age (<it>P </it>= 0.046), but did not differ when considering child age ranges. Multiple linear regression analyses revealed a significant association between Objective SCORAD and QoL measures.</p> <p>Conclusions</p> <p>A strong association between severe AD and poor QoL, both in children and mothers, was found in the Italian sample, in line with the international literature. Family's QoL scores were sensitively related to AD severity, more than the child's QoL, emphasising that the disease has a deep impact on the family. A significant association between age and QoL was only partially found and needs further investigation.</p
Awake Da Vinci robotic partial nephrectomy: First case report ever in a situation of need
We report a unique case of a robotic partial nephrectomy performed under continuous spinal anesthesia (CSA). A 63-year-old woman, active smoker with mild obesity and previous right pneumonectomy, was diagnosed with a growing 5.5-cm renal right cystic tumor. Being at high risk for general anesthesia, a loco-regional approach was indicated. Therefore, after multidisciplinary discussion, a robotic-assisted partial nephrectomy under CSA was considered mandatory. After T4-T5 sensory and motor block, retroperitoneoscopic robot-assisted surgery was successfully performed. Postoperative period was uneventful, with optimal pain control. This unique case demonstrates the feasibility of robotic surgery under CSA, for imperative indications
Effects of 6-month, Multimodal Exercise Program on Clinical and Gait Parameters of Patients with Idiopathic Parkinson's Disease: A Pilot Study
This pilot study aimed to identify the effects of a 6-month, multimodal exercise program on clinical and gait parameters in patients with Parkinson's disease. Two groups of participants were enrolled in the study: Trained Group (TG) and Control Group (CG). Individuals in the TG exercised three times a week for 24 weeks (in a multimodal exercise program), while the CG participants maintained their regular activity level. Participants in both the TG and the CG were assessed at pre- and posttest by clinical rates and the spatiotemporal parameters of self-paced walking. The two groups were not significantly different in demographic, clinical, and gait data at baseline. There were no significant differences between groups for clinical data at posttest. The purposed multimodal exercise program has found improvement in some kinematic gait parameters for the TG. Further study in the form of randomized controlled trial would be required to establish effectiveness of the intervention
- âŚ