SPEEDUP Code for Calculation of Transition Amplitudes via the Effective Action Approach

We present Path Integral Monte Carlo C code for calculation of quantum mechanical transition amplitudes for 1D models. The SPEEDUP C code is based on the use of higher-order short-time effective actions and implemented to the maximal order $p$=18 in the time of propagation (Monte Carlo time step), which substantially improves the convergence of discretized amplitudes to their exact continuum values. Symbolic derivation of higher-order effective actions is implemented in SPEEDUP Mathematica codes, using the recursive Schroedinger equation approach. In addition to the general 1D quantum theory, developed Mathematica codes are capable of calculating effective actions for specific models, for general 2D and 3D potentials, as well as for a general many-body theory in arbitrary number of spatial dimensions.Comment: 17 pages, 3 figures, uses cicp.cl

A Framework for Assessing Nature-Based Urban Stormwater Management Solutions: A Preliminary Spatial Analysis Approach Applied to Southeast Serbia

The development of the stormwater management strategies, e.g., low-impact development (LID), water-sensitive urban design (WSUD), and sustainable drainage solutions (SUDS), was initiated in the mid-1980s as a set of engineering approaches and technologies to reduce the harmful effects of stormwater. Over time, all of them evolved in the holistic, multidisciplinary approaches and, today, they are increasingly viewed and implemented under the umbrella term “Nature-based Solutions” (NbS). The technical elements and measures of these NbS represent various technical solutions, implemented i.a., according to the suitability of the site to achieve their maximum efficiency. Currently, there are no standards or procedures for the application of NbS technologies in Serbia. To overpass this and encourage implementation, we carried out preliminary assessment of NbS elements suitability for application in eight urban settlements in the Region of Southern and Eastern Serbia. The assessment is based on publicly available data and performed according to the existing recommendations in the field of spatial planning and rainwater management for WSUD. The analyses were conducted by GIS tools that involved spatial analyses of various terrain characteristics and provided an insight into the criteria, i.e., constraints that are key to the placement of various technical elements, including bioretention, rain garden, and permeable pavement. Research findings point out that creation of the thematic maps with area suitability ratings for individual NbS stormwater elements might represent a good starting point for further investigation, planning, and design. The proposed framework for preliminary assessment is potentially useful for the countries and regions without regulations in the field of NbS for stormwater management.info:eu-repo/semantics/publishedVersio

Fast Converging Path Integrals for Time-Dependent Potentials I: Recursive Calculation of Short-Time Expansion of the Propagator

In this and subsequent paper arXiv:1011.5185 we develop a recursive approach for calculating the short-time expansion of the propagator for a general quantum system in a time-dependent potential to orders that have not yet been accessible before. To this end the propagator is expressed in terms of a discretized effective potential, for which we derive and analytically solve a set of efficient recursion relations. Such a discretized effective potential can be used to substantially speed up numerical Monte Carlo simulations for path integrals, or to set up various analytic approximation techniques to study properties of quantum systems in time-dependent potentials. The analytically derived results are numerically verified by treating several simple models.Comment: 29 pages, 5 figure

Određivanje izotopa plutonijuma u prizemnim slojevima vazduha na lokaciji Vinča-Beograd u periodu černobiljskog akcidenta

Током друге половине двадесетог века у циљу редовног праћења концентрације радионуклида у аеросолима, вршена су узорковања ваздуха на четири места на локацији Института за нуклеарне науке „Винча“. У време узорковања одређивана је укупна бета активност дневних узорака аеросола на филтер папиру. Како је бета спектрометрија/бројање недеструктивна метода исти узорци су касније искоришћени за алфаспектрометријска мерења. У узорцима ваздуха из периода интензивних надземних нуклеарних проба, као и из периода непосредно након чернобиљског акцидента, током 90-тих година двадесетог века у Лабораторији за нуклеарну и плазма физику одређивана је концентрација изотопа плутонијума алфаспектрометријском методом. Узорковање ваздуха вршено је помоћу пумпе са филтерима. Две године након Чернобиља узорци ваздуха прикупљани током маја 1986. године, су прво мерени на полупроводничком HPGe спектрометру и детектовани су следећи вештачки радионуклиди: 137Cs, 134Cs, 106Ru, 125Sb, 144Ce и 110mAg. Максималне концентрације цезијумових изотопа детектоване су у периоду 02-03. маја, док је други максимум детектован 06. маја. Након гамаспектрометријских, урађена су и алфаспектрометријска мерења. Максималне концентрације 238Pu и 239,240Pu детектоване су у периоду 01-07. маја 1986. године, што одговара хронолошки максимално измереним концентрацијама цезијума. Добијени резултати били су у сагласности са доступним резултатима измереним на локацијама Прага, Минхена и Париза за исти временски период. У узорцима сакупљаним током 1987. и 1989. године, концентрације изотопа плутонијума биле су на граници детекције, осим у пролећном периоду када има највише падавина. Непосредно након чернобиљског акцидента, највећи допринос укупној активности плутонијума у околини потицао је од 241Pu, чистог бета емитера. Мерење овог изотопа може се вршити течним сцинтилационим детектором или масеним спектрометром, који нису били доступни у Институту, те овај радионуклид није ни мерен. Међутим, исти електродепоновани алфа извори плутонијума, припремани почетком деведесетих година прошлог века, поново су мерени алфаспектрометријски током 2004. и 2005. године. Како је од сепарације плутонијума из узорака ваздуха прошло десетак година, што је поредиво са релативно кратким периодом полураспада 241Pu, створени су услови да се концентрација 241Pu у ваздуху одреди преко његовог потомка - 241Am. Активност насталог америцијума одређивана је на основу измерене активности 228Th, и прорачунатог доприноса потомака трасера 236Pu помоћу Bateman-ових једначина. Добијени односи 241Pu/239,240Pu налазе се у границама цитираним у литератури. Резултати вишегодишњих мерења објављени су у више публикација у међународним часописима, као и у саопштењима на домаћим и међународним конференцијама. У овом раду је дата свеобухватна анализа поступака за припрему узорака, процедура радиохемијке сепарације изотопа плутонијума из узорака ваздуха, технике припреме алфаспектроскопски танких извора, специфичности поступака анализе снимљених спектара, као и анализа добијених резултата за специфичне активности изотопа 238Pu, 239,240Pu и 241Pu.For the purpose of regular monitoring of the concentration of radionuclides in aerosols, air sampling was carried out during the second half of XX century in four places at the Institute „Vinča“ site. Gross beta activities of the aerosols were determined daily. Since beta counting is not destructive method, these samples were subsequently used for the alpha spectrometric measurements. Determination of fallout plutonium, as well as plutonium originated from the Chernobyl accident were performed by alpha spectrometry in the Laboratory for nuclear and plasma physics. Air sampling was performed by pumps with filters. Air samples collected during May 1986 were measured by semiconductor HPGe spectrometer, and the following artificial radionuclides: 137Cs, 134Cs, 106Ru, 125Sb, 144Ce and 110mAg were detected. Maximal concentration of cesium isotopes were observed on 02-03 May, while second maximum was detected on 06 May. Alphaspectrometric measurements of plutonium isotopes indicated also that maximal concentration of 238Pu and 239,240Pu occurred in the period 01-07 May. Obtained results were in agreement with ones reported in literature for locations of Prague, Munich, and Paris for the same period. Monitoring of air during 1987 and 1989 showed that plutonium isotopes concentrations were below minimal detectable values, except in spring time due to abundant precipitation. The same plutonium sources, prepared during the 90s were re-measured in 2004 and 2005, in order to determine concentration of 241Pu (pure beta emitter) by alpha spectrometry using “Am in-growth Method”. Activity of in-growth americium was determined experimentally, based on measured activity of 228Th, and additionally calculated using the contribution of 236Pu (used as a tracer) descendants obtained by the Bateman’s equations. Obtained activity ratios 241Pu/239,240Pu were within the limits cited in the literature. The result of perennial measurement have been published in several publications in international journals, and presented at numerous national and international conferences. Comprehensive analysis of sample preparation, radiochemical procedure of plutonium separation from air samples, alpha - sources preparation techniques, analysis of recorded spectra, as well as analysis of obtained results for 238Pu, 239,240Pu and 241Pu concentrations are presented in this paper.Article is part of: [http://vinar.vin.bg.ac.rs/handle/123456789/8230

Radionuclide Content in Laundry Detergents Commercially Available on the Serbian Market and Assessment of Radiological Environmental Hazards

Laundry detergents are chemicals widely used in everyday life, and in numerous industry branches. In order to perceive the radiological aspect of environmental pollution by wastewater, the analysis of laundry detergents available on the Serbian market was undertaken. Laundry detergent samples were measured by means of gamma spectrometry and the results are presented in this paper. Analysis of the obtained activity concentrations showed that laundry detergents in Serbia mostly fulfill the international recommendation and requirements regarding the phosphate content. Besides that, the content of the detected radionuclides in laundry detergent samples indicates the minor radiological risk to the environment via wastewaters

A Non-Singular Black Hole

We present a completely integrable deformation of the CGHS dilaton gravity model in two dimensions. The solution is a singularity free black hole that at large distances asymptoticaly joins to the CGHS solution.Comment: 11 pages, 1 figure, Latex 2

Market Concentration and Market Power / Koncentrisanost tržišta i tržišna moć

Contemporary directions of the market liberalization should lead to a bigger number of market participants and to a bigger degree of competition among them. This again, leads to a more diversified offer and to bigger quality products along with higher level of services with cheaper rates. In order to control the mentioned processes, analysis of market concentration is needed, as well as studying and perfection of the methods that allow measurement of market concentration. The degree of market concentration which on a specific market one or more economic subjects have is defined as ‘’market power’’. Economic efficiency on a specific market largely depends on whether non competitive market structures which produce adverse effects on economic efficiency are existent on that market, which ultimately affects on the overall well – being. Conversance of the degree of concentration of a specific (relevant) market is important so that breaching of the market principles can be timely spotted and so that appropriate measures can be taken. Supervision over the market and the market processes, as well as appliance of specific measuring methods of market concentration have the goal of establishing and maintenance of free market competition in which all of the economic subjects participate under the same conditions

Zajedničko ulaganje (joint venture) i tržišna konkurencija / Joint Venture and Market Competition

In modern business of the business entities, on the EU market, as well as on the other national markets, it is joint venture is increasingly used as a form of joining of business entities. For a competition law basic question is an effect on the market competition of this joining of the business entities. The effects made by joint ventures on market competition may be positive, which is the case with the invention, the availability of new technologies, increasing of the efficiency, new products etc., or negative, which is the case with market separation or closing of the market for new participants. In European competition law there is an opinion that there is greater possibility of the negative effects on market competition when real or potential competitors make joint venture. Authority for protection of competition on two basis can evaluate joint venture. The first base is joint venture, which is evaluated as concentration of the business entities, and the second base is joint venture, which is evaluated as an agreement between business entities. This paper shall elaborate both basis, paying special attention on its demarcation, as well as the effects they have on market competition. In addition, the paper shall show and explain the most common modalities of the joint venture agreements, and point out their differences between them