Surface detonation in type Ia supernova explosions?

We explore the evolution of thermonuclear supernova explosions when the progenitor white dwarf star ignites asymmetrically off-center. Several numerical simulations are carried out in two and three dimensions to test the consequences of different initial flame configurations such as spherical bubbles displaced from the center, more complex deformed configurations, and teardrop-shaped ignitions. The burning bubbles float towards the surface while releasing energy due to the nuclear reactions. If the energy release is too small to gravitationally unbind the star, the ash sweeps around it, once the burning bubble approaches the surface. Collisions in the fuel on the opposite side increase its temperature and density and may -- in some cases -- initiate a detonation wave which will then propagate inward burning the core of the star and leading to a strong explosion. However, for initial setups in two dimensions that seem realistic from pre-ignition evolution, as well as for all three-dimensional simulations the collimation of the surface material is found to be too weak to trigger a detonation.Comment: 5 pages, 3 figures, in: Proceedings of the SciDAC 2006 Meeting, Denver June 25-26 2006, also available at http://herald.iop.org/jpcs46/m51/gbr//link/40

Hofstadter butterfly in a cavity-induced dynamic synthetic magnetic field

Energy bands of electrons in a square lattice potential threaded by a uniform magnetic field exhibit a fractal structure known as the Hofstadter butterfly. Here we study a Fermi gas in a 2D optical lattice within a linear cavity with a tilt along the cavity axis. The hopping along the cavity axis is only induced by resonant Raman scattering of transverse pump light into a standing-wave-cavity mode. Choosing a suitable pump geometry allows us to realize the Hofstadter-Harper model with a cavity-induced dynamical synthetic magnetic field, which appears at the onset of the superradiant phase transition. The dynamical nature of this cavity-induced synthetic magnetic field arises from the delicate interplay between collective superradiant scattering and the underlying fractal band structure. Using a sixth-order expansion of the free energy as a function of the order parameter and by numerical simulations, we show that at low magnetic fluxes the superradiant ordering phase transition is first order, while it becomes second order for higher flux. The dynamic nature of the magnetic field induces a nontrivial deformation of the Hofstadter butterfly in the superradiant phase. At strong pump far above the self-ordering threshold, we recover the Hofstadter butterfly one would obtain in a static magnetic field

Electromagnetic analysis and performance comparison of fully 3D-printed antennas

In this work, the possibility of directly prototyping antennas by exploiting additive manufacturing 3D-printing technology is investigated. In particular, the availability of printable filaments with interesting conductive properties allows for printing of even the antenna conductive elements. Three samples of a 2.45 GHz microstrip patch antenna have been 3D-printed by using different approaches and materials, and their performance evaluated and compared. In particular, the same dielectric substrate printed in polylactic acid (PLA) has been adopted in all cases, whilst copper tape and two different conductive filaments have been used to realize the conductive parts of the three antenna samples, respectively. Even if an expected radiation efficiency reduction has been observed for the conductive filament case, the comparative analysis clearly demonstrates that 3D-printing technology can be exploited to design working fully-printed antennas, including the conductive parts

Evidence on Problematic Online Gaming and Social Anxiety over the Past Ten Years: a Systematic Literature Review

Purpose of Review: The present study aimed to review the literature concerning the relationship between problematic online gaming (POG) and social anxiety, taking into account the variables implicated in this relationship. This review included studies published between 2010 and 2020 that were indexed in major databases with the following keywords: Internet gaming, disorder, addiction, problematic, social phobia, and social anxiety. Recent Findings: In recent years, scientific interest in POG has grown dramatically. Within this prolific research field, difficulties associated with social anxiety have been increasingly explored in relation to POG. Indeed, evidence showed that individuals who experience social anxiety are more exposed to the risk of developing an excessive or addictive gaming behavior. Summary: A total of 30 studies satisfied the initial inclusion criteria and were included in the present literature review. Several reviewed studies found a strong association between social anxiety and online gaming disorder. Furthermore, the relationships among social anxiety, POG, age, and psychosocial and comorbid factors were largely explored. Overall, the present review showed that socially anxious individuals might perceive online video games as safer social environments than face-to-face interactions, predisposing individuals to the POG. However, in a mutually reinforcing relationship, individuals with higher POG seem to show higher social anxiety. Therefore, despite online gaming might represent an activity able to alleviate psychopathological symptoms and/or negative emotional states, people might use online gaming to counterbalance distress or negative situations in everyday life, carrying out a maladaptive coping strategy

new beam scanning device for active beam delivery system bds in proton therapy

Abstract A new Beam Delivery System (BDS) has been studied in the framework of a new proton therapy project, called AMIDERHA. It is characterized by an active scanning system for target irradiation with a pencil beam. The project is based on the use of a Linac with variable final energy and the Robotized Patient Positioning System instead of the traditional gantry. As a consequence, in the active BDS of AMIDERHA a pencil beam scanning system with a relatively long Source to Axis Distance (SAD) can be used. In this contribution, the idea of using a unique new device capable of both horizontal and vertical beam scansion for the AMIDERHA active BDS will be presented and discussed. Furthermore, a preliminary design of that device will be shown, together with the results of simulations

Oral mucositis: a survey on changes in the proteomic profile

Objectives. Oral mucositis is the most severe complication of anticancer therapy. It occurs in 40-85% of patients during chemotherapy and radiotherapy but also in patients who have undergone hematopoietic stem cell transplantation. The symptoms for oral mucositis are burning and severe pain oral, spontaneous bleeding, dysphagia, dysarthria and odynophagia; especially pain and burning sensation on swallowing contribute to decreased quality of life for oncologic patients and, in severe cases, may also force the patient to feed parenterally (1). Furthermore, if the mucositis is severe it can lead to partial or complete interruption of radiotherapy before completion of the treatment protocol with consequent worsening of the prognosis (2, 3). Dentists must be familiar with the necessary intervents, in order to help the patient during the course of the treatment and prevent the interruption. Certain measures may help minimize the symptoms associated with oral mucositis; however, further research is required, focusing on lesion prevention prior to treatment initiation. To this end, it has been investigated the salivary proteome of cancer patients who developed oral mucositis, post chemotherapy and/or radiotherapy. In addition, we compared the salivary proteome of the same subjects before developing oral mucositis and immediately after the treatment for the mucositis. The analysis was made with SELDI technology. Methods. In the current study, 55 saliva samples of patients suffering from different types of cancer were analyzed. The saliva was collected in three times: before the development of mucositis, when it was diagnosed and after the resolution of this pathology. All samples were analyzed by SELDI-TOF/MS analysis. It was possible to create cluster peaks in spectra obtained using BIORAD DataManagerTM software (Ver 3.5). Results. From this analysis we identified a list of differently expressed mass peaks (clusters). We have selected some significant peaks in a range of values between 3000 m/z 15000 m/z. In particular, five were found to be differentially expressed: 3343, 3486, 3732, 4132 and 4786 m/z. The analysis of the cluster, we evaluated different patterns of peaks in the three groups; some of these were up regulated, as the peak 3732 m/z in samples pre mucositis, and down regulated, such as the 7101 m/z in the samples pre mucositis. It is noted, moreover, an important increase of the peak 4132 m/z in samples of mucositis. Conclusions. Oral mucositis is one of the most frequent complications of cancer therapies. It is, therefore, extremely important that the mucositis is prevented whenever possible, or at least treated to reduce its severity and possible complications. Knowing the salivary proteome and its variations in a state of pre mucositis, mucositis and post mucositis can be useful in order to intervene with preventive tools and better therapies. The association of the peaks 3343, 3486, 3732, 4132 and 4786 m / z, in particular the increase in expression of the peak 4132 m / z in samples of mucositis makes us think that it can be used as biomarker of this condition. Therefore, if these data will be confirmed on a larger series of patients could identify these proteins and study of targeted therapies. Furthermore, it would be helpful to understand whether these variations are associated with a particular chemotherapy and evaluate longer available cancer therapies replacement