The volatility of realized volatility

Using unobservable conditional variance as measure, latent-variable approaches, such as GARCH and stochastic-volatility models, have traditionally been dominating the empirical finance literature. In recent years, with the availability of high-frequency financial market data modeling realized volatility has become a new and innovative research direction. By constructing "observable" or realized volatility series from intraday transaction data, the use of standard time series models, such as ARFIMA models, have become a promising strategy for modeling and predicting (daily) volatility. In this paper, we show that the residuals of the commonly used time-series models for realized volatility exhibit non-Gaussianity and volatility clustering. We propose extensions to explicitly account for these properties and assess their relevance when modeling and forecasting realized volatility. In an empirical application for S&P500 index futures we show that allowing for time-varying volatility of realized volatility leads to a substantial improvement of the model's fit as well as predictive performance. Furthermore, the distributional assumption for residuals plays a crucial role in density forecasting. Klassifikation: C22, C51, C52, C5

The Volatility of Realized Volatility

Using unobservable conditional variance as measure, latent–variable approaches, such as GARCH and stochastic–volatility models, have traditionally been dominating the empirical finance literature. In recent years, with the availability of high–frequency financial market data modeling realized volatility has become a new and innovative research direction. By constructing “observable” or realized volatility series from intraday transaction data, the use of standard time series models, such as ARFIMA models, have become a promising strategy for modeling and predicting (daily) volatility. In this paper, we show that the residuals of the commonly used time–series models for realized volatility exhibit non–Gaussianity and volatility clustering. We propose extensions to explicitly account for these properties and assess their relevance when modeling and forecasting realized volatility. In an empirical application for S&P500 index futures we show that allowing for time–varying volatility of realized volatility leads to a substantial improvement of the model’s fit as well as predictive performance. Furthermore, the distributional assumption for residuals plays a crucial role in density forecasting.Finance, Realized Volatility, Realized Quarticity, GARCH, Normal Inverse Gaussian Distribution, Density Forecasting

ASSESSING THE BUSINESS INCUBATORS’ PERFORMANCE REFERRING THE LOCAL DEVELOPMENT IN ITALY

Literature assign to business incubators an important role in promoting innovative entrepreneurship and economic growth. This study investigates the relationship between incubators performance and local development in Italy, focusing on those characteristics of regional contexts that enhance the role of incubators. Using a sample of 162 incubators, the regional economic index for 18 regions and the performance data for 405 new technology ventures located within these regions, we show that the local context features play a positive effect on the incubators performance. The nature of founders team of incubators is also important to implement effective entrepreneurial initiatives, while the sectorial specialization isn’t an essential requirement for the success of NTVs. Different factors of local context contribute positively to generate an environment that enhance the incubators’ activities

Monopolistic professional closure, family credentials and examination procedures in the Venetian College of Accountants (16th-17th century)

Peer reviewedPostprin

Novel CircRNA Discovery in Sheep Shows Evidence of High Backsplice Junction Conservation

Circular RNAs (circRNAs) are covalently closed circular non-coding RNAs. Due to their structure, circRNAs are more stable and have longer half-lives than linear RNAs making them good candidates for disease biomarkers. Despite the scientific relevance of these molecules, the study of circRNAs in non-model organisms is still in its infancy. Here, we analyse total RNA-seq data to identify circRNAs in sheep from peripheral blood mononuclear cells (PBMCs) and parietal lobe cortex. Out of 2510 and 3403 circRNAs detected in parietal lobe cortex and in PBMCs, a total of 1379 novel circRNAs were discovered. Remarkably, around 63% of all detected circRNAs were found to be completely homologous to a circRNA annotated in human. Functional enrichment analysis was conducted for both tissues based on GO terms and KEGG pathways. The enriched terms suggest an important role of circRNAs from encephalon in synaptic functions and the involvement of circRNAs from PBMCs in basic immune system functions. In addition to this, we investigated the role of circRNAs in repetitive vaccination experiments via differential expression analysis and did not detect any significant relationship. At last, our results support both the miRNA sponge and the miRNA shuttle functions of CDR1-AS in sheep brain. To our knowledge, this is the first study on circRNA annotation in sheep PBMCs or parietal lobe cortex samples.This work was supported by a Spanish Ministry of Economy grant AGL2013-49137-C3 to BMJ; EV-M is a predoctoral fellow from the University of the Basque Country (UPV/EHU) [PIF15/361] and received a grant for a short-term scientific mission (STSM) from the Functional Annotation of Animal Genomes—European network (FAANG-Europe) [COST Action CA15112

Photoionization of monocrystalline CVD diamond irradiated with ultrashort intense laser pulse

Direct laser writing of conductive paths in synthetic diamond is of interest for implementation in radiation detection and clinical dosimetry. Unraveling the microscopic processes involved in laser irradiation of diamond below and close to the graphitization threshold under the same conditions as the experimental procedure used to produce three-dimensional devices is necessary to tune the laser parameters to optimal results. To this purpose a transient currents technique has been used to measure laser-induced current signals in monocrystalline diamond detectors in a wide range of laser intensities and at different bias voltages. The current transients vs time and the overall charge collected have been compared with theoretical simulations of the carrier dynamics along the duration and after the conclusion of the 30 fs laser pulse. The generated charge has been derived from the collected charge by evaluation of the lifetime of the carriers. The plasma volume has also been evaluated by measuring the modified region. The theoretical simulation has been implemented in the framework of the empirical pseudopotential method extended to include time-dependent couplings of valence electrons to the radiation field. The simulation, in the low-intensity regime, I\ensuremath{\sim}1\phantom{\rule{0.28em}{0ex}}\mathrm{TW}/{\mathrm{cm}}^{2}, predicts substantial deviation from the traditional multiphoton ionization, due to nonperturbative effects involving electrons from degenerate valence bands. For strong field with intensity of about $50\phantom{\rule{0.28em}{0ex}}\mathrm{TW}/{\mathrm{cm}}^{2}$, nonadiabatic effects of electron-hole pair excitation become prominent with high carrier densities eventually causing the optical breakdown of diamond. The comparison of theoretical prediction with experimental data of laser-generated charge vs laser energy density yields a good quantitative agreement over six orders of magnitude. At the highest intensities the change of slope in the trend is explained taking into account the dependence of the optical parameters and the carrier mobility on plasma density

Ophthalmic complications of Lemierre syndrome

PURPOSE: Lemierre syndrome is a life-threatening condition characterized by head/neck bacterial infection, local suppurative thrombophlebitis and septic embolic complications in a range of sites of distant organs. No prior study focused on the course and characteristics of ophthalmic complications of Lemierre syndrome. METHODS: We analysed data of 27 patients with ophthalmic complications from a large cohort of 712 cases with Lemierre syndrome reported globally between 2000 and 2017. We focused on initial manifestations, early (in-hospital) course and long-term ophthalmic deficits at the time of hospital discharge or during postdischarge follow-up. The study protocol was registered in the International Prospective Register of Systematic Reviews PROSPERO (CRD42016052572). RESULTS: Nine (33%) patients were women; the median age was 20 (Q1-Q3: 15-33) years. Fusobacterium spp. was involved in 56% of cases. The most prevalent initial manifestations were decreased vision (35%) and periocular oedema (38%), followed by impaired eye movements/nerve palsy (28%) and proptosis (28%). Venous involvement, notably cerebral vein thrombosis (70%) and ophthalmic vein thrombosis (55%), explained the symptomatology in most cases. Septic embolism (7%), orbital abscesses (2%) and carotid stenosis (14%) were also present. Ophthalmic sequelae were reported in 9 (33%) patients, often consisting of blindness or reduced visual acuity, and nerve paralysis/paresis. CONCLUSION: Ophthalmic complications represent a severe manifestation of Lemierre syndrome, often reflecting an underlying cerebral vein thrombosis. Visual acuity loss and long-term severe complications are frequent. We call for an interdisciplinary approach to the management of patients with Lemierre syndrome and the routine involvement of ophthalmologists

Linear mitochondrial DNA is rapidly degraded by components of the replication machinery.

Emerging gene therapy approaches that aim to eliminate pathogenic mutations of mitochondrial DNA (mtDNA) rely on efficient degradation of linearized mtDNA, but the enzymatic machinery performing this task is presently unknown. Here, we show that, in cellular models of restriction endonuclease-induced mtDNA double-strand breaks, linear mtDNA is eliminated within hours by exonucleolytic activities. Inactivation of the mitochondrial 5'-3'exonuclease MGME1, elimination of the 3'-5'exonuclease activity of the mitochondrial DNA polymerase POLG by introducing the p.D274A mutation, or knockdown of the mitochondrial DNA helicase TWNK leads to severe impediment of mtDNA degradation. We do not observe similar effects when inactivating other known mitochondrial nucleases (EXOG, APEX2, ENDOG, FEN1, DNA2, MRE11, or RBBP8). Our data suggest that rapid degradation of linearized mtDNA is performed by the same machinery that is responsible for mtDNA replication, thus proposing novel roles for the participating enzymes POLG, TWNK, and MGME1

Novel geometrical concept of a high-performance brain PET scanner. Principle, design and performance estimates

We present the principle, a possible implementation and performance estimates of a novel geometrical concept for a high-resolution positron emission tomograph. The concept, which can be for example implemented in a brain PET device, promises to lead to an essentially parallax-free 3D image reconstruction with excellent spatial resolution and constrast, uniform over the complete field of view. The key components are matrices of long axially oriented scintillator crystals which are read out at both extremities by segmented Hybrid Photon Detectors. We discuss the relevant design considerations for a 3D axial PET camera module, motivate parameter and material choices, and estimate its performance in terms of spatial and energy resolution. We support these estimates by Monte Carlo simulations and in some cases by first experimental results. From the performance of a camera module, we extrapolate to the reconstruction resolution of a 3D axial PET scanner in a semi-analytical way and compare it to an existing state-of-the art brain PET device. We finally describe a dedicated data acquisition system, capable to fully exploit the advantages of the proposed concept. We conclude that the proposed 3D axial concept and the discussed implementation is a competitive approach for high-resolution brain PET. Excellent energy resolution and Compton enhanced sensitivity are expected to lead to high-quality reconstruction and reduced scanning times