Thin accretion disks around cold Bose-Einstein Condensate stars

Due to their superfluid properties some compact astrophysical objects, like neutron or quark stars, may contain a significant part of their matter in the form of a Bose-Einstein Condensate. Observationally distinguishing between neutron/quark stars and Bose-Einstein Condensate stars is a major challenge for this latter theoretical model. An observational possibility of indirectly distinguishing Bose-Einstein Condensate stars from neutron/quark stars is through the study of the thin accretion disks around compact general relativistic objects. In the present paper, we perform a detailed comparative study of the electromagnetic and thermodynamic properties of the thin accretion disks around rapidly rotating Bose-Einstein Condensate stars, neutron stars and quark stars, respectively. Due to the differences in the exterior geometry, the thermodynamic and electromagnetic properties of the disks (energy flux, temperature distribution, equilibrium radiation spectrum and efficiency of energy conversion) are different for these classes of compact objects. Hence in this preliminary study we have pointed out some astrophysical signatures that may allow to observationally discriminate between Bose-Einstein Condensate stars and neutron/quark stars, respectively.Comment: 21 pages, 12 figures, accepted for publication in EPJC; reference adde

The Economic Value regarding the Protection Activities of Critical Infrastructures

In the past two years, a number of European countries, members of EU, Australia and Canada have initiated substantive actions in PIC area, establishing bodies responsible, defining procedures and methodologies, allocating significant resources to protect critical infrastructure considered essential or vital. The security concept, and implicit, the economical and energetic ones have different use and defining in relation to the history and organizational culture of every nation. A decisive contribution in the process of defining those concepts is identifying the set of values and national interests, elements that usually are the result of the public opinion perception. The increased share of non-military risks and threats has determined the national security management reconsideration, becoming more obvious the necessity of “public-private partnership” approach. A new concept is becoming more and more present and gains maximum generality significations. This kind of process reconfigures the position and the role of social state actors: the political class, the business and scientific environment, civil society and citizens

Jacobi stability analysis of scalar field models with minimal coupling to gravity in a cosmological background

We perform the study of the stability of the cosmological scalar field models, by using the Jacobi stability analysis, or the Kosambi-Cartan-Chern (KCC) theory. In the KCC approach we describe the time evolution of the scalar field cosmologies in geometric terms, by performing a "second geometrization", by considering them as paths of a semispray. By introducing a non-linear connection and a Berwald type connection associated to the Friedmann and Klein-Gordon equations, five geometrical invariants can be constructed, with the second invariant giving the Jacobi stability of the cosmological model. We obtain all the relevant geometric quantities, and we formulate the condition of the Jacobi stability for scalar field cosmologies in the second order formalism. As an application of the developed methods we consider the Jacobi stability properties of the scalar fields with exponential and Higgs type potential. We find that the Universe dominated by a scalar field exponential potential is in Jacobi unstable state, while the cosmological evolution in the presence of Higgs fields has alternating stable and unstable phases. By using the standard first order formulation of the cosmological models as dynamical systems we have investigated the stability of the phantom quintessence and tachyonic scalar fields, by lifting the first order system to the tangent bundle. It turns out that in the presence of a power law potential both these models are Jacobi unstable during the entire cosmological evolution.Comment: 24 pages, 14 figures, accepted for publication in Advances in High Energy Physics, special issue "Dark Physics in the Early Universe

Smart Electronic System for Monitoring Water Quality Parameters in Fish Tanks

Fish farming represents a strong link in the value chain of food distribution over the world. There are different types of farms like RAS, continuously water alimented pounds, lake, maritime, etc. The self-cleaning water capability of a tank system is the key factor in describing RAS (recirculating aquaculture system) systems. This factor is crucial for the survival of farmed fish in urban aquaculture systems. The aim of this paper consists in describing the design and the functionality of a smart electronic system, capable of monitoring water quality parameters, in order to monitor the fish tanks’ environment and making decisions about undesirable events that may affect them. If unpleasant events occur, such as the parameter’s level no longer falls within the preseted limits, an alarm is set to warn the user. Automatization of the system will be conceived to close the power and/or water supply circuit in case there was no human intervention within a certain period of time in the fish tanks. This paper is based on the ongoing research of the iPREMAS aquaculture project. The system from the iPREMAS project contains sensors for monitoring the essential water quality parameters for the growth, reproduction and qualitative and quantitative improvement of fish population, such as pH level, water temperature, dissolved oxygen level, water salinity, water level, conductivity and will be improved with sensors to monitor the level of nitrates and nitrites. The sensors are to be connected to a special designed electronic module and will transmit the information to an electronic control module based on a development kit containing a microcontroller for the automatization of the system. A database is used to store the data and a software application is used to visualize the data transmitted by the sensors that will communicate with the database and display the values in real time

THE FRAMEWORK STRATEGY RELATED TO SECURITY IN SOUTH-EASTERN EUROPE

When discussing the current strategic environment, there is the "when" of the Cold War and the first half of the '90s, and the "now" of today. The changing demography and migration patterns, ethnic and religious tensions, environmental degradation, instability coming from states that are likely to decline or have already fallen, and growing proliferation of weapons are just some of the problems that have exacerbated the differences between security "then" and "now", such as the transnational terrorist attacks after September 11, 2001. The concept of security was much disputed, as seen from a study of the United Nations in 1986, developed by a group of experts on the concept of security, resulting in the existence of a limited conceptual similarity between them Mankind has always been concerned with building or rebuilding peace and security During the Cold War, Central and Eastern European countries were not talking about a national security concept in the Western sense of the word, but about a military doctrine of the Warsaw Pact and, in some cases, as was that of Romania, about a national military doctrine. After the fall of the Iron Curtain, those countries have gradually chosen to use the concept of national security, a term that takes into account all types of threats to national interests, and also the whole range of ways to counter them, the military not having the leading role any longer

The Economic Value regarding the Protection Activities of Critical Infrastructures

In the past two years, a number of European countries, members of EU, Australia and Canada have initiated substantive actions in PIC area, establishing bodies responsible, defining procedures and methodologies, allocating significant resources to protect critical infrastructure considered essential or vital. The security concept, and implicit, the economical and energetic ones have different use and defining in relation to the history and organizational culture of every nation. A decisive contribution in the process of defining those concepts is identifying the set of values and national interests, elements that usually are the result of the public opinion perception. The increased share of non-military risks and threats has determined the national security management reconsideration, becoming more obvious the necessity of “public-private partnership” approach. Anew concept is becoming more and more present and gains maximum generality significations. This kind of process reconfigures the position and the role of social state actors: the political class, thebusiness and scientific environment, civil society and citizens

THE NEW DIMENSION OF THREATS THAT THE EUROPEAN ACTORS ARE SUBJECT TO IN NEIGHBORING STATES CRISIS MANAGEMENT

Restructuring activities of the current international system increases the amplification of the existing inequalities in developing countries with unlimited potential for the European market. Thus, amid security system vulnerabilities and uncontrolled situations, the local conflicts may spread to neighboring regions, affecting also the strategic security environment. The dynamics of political and military events reveals that security and defense go beyond the responsibility of a single country, a fact which causes a greater involvement of democratic states and international organizations. Against this background, the work in question provides not only an insight into the new international dimension, but also a possible response version in order to enable risk and vulnerabilities (of economic, social or religious nature) management, in the benefit of all. Therefore, restricting undesirable phenomena can be achieved by harmonizing the actions on the various interest sectors at national or international level, similar to the objectives underlying the American concept of "homeland security". As a solution, the concept itself connects everything that can be connected, when we talk about security, in a widespread network of state intervention mechanisms, namely, the external instruments of power. For this reason, homeland security is characterized by a plurality of stakeholders, from a local and national level to a European and transatlantic one

Usefulness of Imaging and Biological Tools for the Characterization of Portal Vein Thrombosis in Hepatocellular Carcinoma

This study aims to evaluate the performance of contrast-enhanced ultrasound (CEUS) and biological tests to characterize portal vein thrombosis (PVT). We retrospectively analyzed 101 patients with PVT, liver cirrhosis, and hepatocellular carcinoma (HCC). In all patients, demographic, biologic, imaging, and endoscopic data were collected. All patients underwent CEUS and a second line imaging technique (CE-CT/MRI) to characterize PVT. Of the 101 cirrhotic subjects, 77 (76.2%) had HCC. CEUS had 98.6% sensitivity (Se) and 89.3% specificity (Sp) for the characterization of PVT type. A significant correlation was found between alpha-fetoprotein (AFP) levels and the PVT characterization at CEUS (r = 0.28, p = 0.0098) and CT/MRI (r = 0.3, p = 0.0057). Using the AFP rule-out cutoff values for HCC (AFP < 20 ng/dL), 78% of the subjects were correctly classified as having benign PVT, while 100% of the subjects were correctly classified as tumor-in-vein (TIV) when the rule-in cutoff value was used (AFP ≥ 200 ng/dL). Using multiple regression analysis, we obtained a score for classifying PVT. The PVT score performed better than CEUS (AUC—0.99 vs. AUC—0.93, p = 0.025) or AFP serum levels (AUC—0.99 vs. AUC—0.96, p = 0.047) for characterizing PVT. In conclusion, CEUS is a sensitive method for the characterization of PVT. The PVT score had the highest performance for PVT characterization