1,131 research outputs found
Entanglement and quantum phase transitions in matrix product spin one chains
We consider a one-parameter family of matrix product states of spin one
particles on a periodic chain and study in detail the entanglement properties
of such a state. In particular we calculate exactly the entanglement of one
site with the rest of the chain, and the entanglement of two distant sites with
each other and show that the derivative of both these properties diverge when
the parameter of the states passes through a critical point. Such a point
can be called a point of quantum phase transition, since at this point, the
character of the matrix product state which is the ground state of a
Hamiltonian, changes discontinuously. We also study the finite size effects and
show how the entanglement depends on the size of the chain. This later part is
relevant to the field of quantum computation where the problem of initial state
preparation in finite arrays of qubits or qutrits is important. It is also
shown that entanglement of two sites have scaling behavior near the critical
point
Health risk assessment of selected heavy metals in some edible fishes from Gorgan Bay, Iran
The objective of this study was to assess the bioaccumulation of heavy metals (Cd, Pb, Cr and Fe) in the muscles of five fish species (Sander lucioperca, Liza auratus, Alosa caspia, Cyprinus carpio and Liza saliens) from Gorgan Bay in the south-eastern Caspian Sea, in order to determine the value daily intake of heavy metals by consumption of fish and human health risk assessment. The concentration of metals was estimated using graphite furnace atomic absorption spectrometer. Potential health risk assessments based on estimated daily intake (EDI) values and target hazard quotient (THQ) indicated that the intakes of metals by consuming these fish species do not result in an appreciable hazard risk for the human body. The hazard index (HI) calculated was lower than 1 for all the species. However, the results indicate that the high concentrations of Pb (in the muscle of L. auratus) and Fe in all fish is alarming
A needs assessment of fish (common carp) culture agency members in Guilan and Mazandaran Province
The main objective of this study is an investigation of educational needs of fish is cammon carp Proudation cooperatives and effective factors on mentioned educational needs. This research was applicable from objective point of view and descriptive-correlation method considering its method, which has been done with survey approach. The statistical population is the members of the fish is cammon carp Proudation cooperatives in Guilan&mazandaran Province which were included 2235 persons. Among this population, 160 persons were selected using Cochran formula and proportional stratified random sampling method. Managers production Which were 19 production cooperatives in the province, was census through the survey method Meanwhile, the total number of 38 experienced experts in fishculture of Guilan & mazandaran provinces Fisheries Researeach organization .The main tool for data collection was questionnaire and its reliability was calculated by Cronbach’s alpha coefficient, The main tool for data collection survey questionnaire and its reliability by a panel of experts confirmed were valid questionnaire study using the alpha coefficient to mean parts inventory intensive manufactures 73% and surveys of experts and managers of cooperatives by Cronbach’s alpha coefficient of 78% was calculated More than 70 percent of the average of the current knowledge of warm water fish production in Guilan and Mazandaran is moderate to high. Educational needs of producers fish in warm- water showed a significant relationship between income level and their knowledge. Results showed that the management of health and diseases in warm-water fish farms, fish farms, water management, and site selection and construction of warm water from the producers' point of view, experts and managers of cooperatives is the educational priority
Different voices from community groups to support sustainable tourism development at Iranian World Heritage Sites: evidence from Bisotun
This empirical study investigates the causal factors affecting support for sustainable tourism development (SSTD) at a world heritage site in Bisotun, a city in Kermanshah Province, Iran. It uses social exchange theory to assess the effects of community attachment, community involvement, perceived benefits, and perceived costs on SSTD. Using social identity theory, it identifies whether these associations significantly vary across four different community groups: farmers, businesses, handicraft sellers, and local government employees. A questionnaire was administered to 489 respondents from these four community groups in the Bisotun area. The hypotheses were tested using structural equation modelling and invariance metric tests. The results revealed that community attachment, community involvement, and perceived benefits had a significant and positive impact on SSTD. The results of the metric invariance tests show that the effects of community attachment and community involvement on SSTD varied across the community groups at this world heritage site located in a developing country. The study discusses the theoretical and managerial implications of these findings
Quantum discord and non-Markovianity of quantum dynamics
The problem of recognizing (non-)Markovianity of a quantum dynamics is
revisited through analyzing quantum correlations. We argue that
instantaneously-vanishing quantum discord provides a necessary and sufficient
condition for Markovianity of a quantum map. This is used to introduce a
measure of non-Markovianity. This measure, however, requires demanding
knowledge about the system and the environment. By using a quantum correlation
monogamy property and an ancillary system, we propose a simplified measure with
less requirements. Non-Markovianity is thereby decided by quantum state
tomography of the system and the ancilla.Comment: 5 pages, 3 figure
Relation between clinical features and gastric emptying time in diabetic patients
BACKGROUND: Gastroparesis is characterized by delayed gastric emptying. This pathology is usually observed in patients with diabetes. One standard approach to quantitative assessment of gastric emptying is scintigraphic study. The aim of present study was to perform scintigraphic study of gastric emptying time in patient with diabetes and to find its correlation with patients' characteristics. MATERIALS AND METHODS: Gastric emptying was assessed in 19 patients with type 2 diabetes (mean age of 61.04 ± 6.09 years) and 6 healthy volunteers. Characteristics of the patients were sex, age, duration of diabetes, blood sugar and serum HbA1c level. RESULTS: Results of present study revealed that gastric emptying half time was significantly larger in patients with type 2 diabetes as compared with healthy volunteers (P-value < 0.05). While correlation of sex, age, duration of diabetes and blood sugar with gastric emptying time was not statistically significant, HbA1c level had significant effect on gastric emptying time. CONCLUSION: Results of this prospective study indicated that level of serum HbA1c is an effecting factor on gastric emptying time in patients with type 2 diabetes; however, these preliminary findings should be validated in larger and well-designed studies. Copyright © 2015 Via Medica
Approximation algorithms for guarding holey polygons
Guarding edges of polygons is a version of art gallery problem.The goal is finding the minimum number of guards to cover the edges of a polygon. This problem is NP-hard, and to our knowledge there are approximation algorithms just for simple polygons. In this paper we present two approximation algorithms for guarding polygons with holes.Keywords: guarding, approximation algorithm, vertex guard, edge guar
The impact of mental illnesses on the clinical manifestations of COVID-19 patients
Background: The underlying medical conditions with COVID-19 patients may affect the clinical symptoms, morbidity and mortality. Due to the high prevalence of mental illnesses and their impact on inflammatory processes and pulmonary function, we evaluated the impact of depression and anxiety as the highest prevalence of mental illness on clinical manifestations of COVID-19 patients.Methods: A questionnaire form about past medical history completed for the COVID-19 patients. Patients with underlying depression and anxiety excluded and compared with the patients without comorbidities of medical or mental conditions in terms of the common clinical manifestations.Results: Total out of the 560 patients reviewed, 174 patients had no history of any disease (named as group A). 39 patients had the history of depression only and 45 patients had the history of anxiety only (respectively named as groups B and C). There was a high and meaningful frequency of feeling dyspnea (p value 0.05).Conclusions: Comorbidity of depression and anxiety may affect the clinical symptoms in patients with COVID-19. Respiratory symptoms (e.g., cough, tachypnea and feeling dyspnea), tachycardia and chest pain are the more manifested symptoms in the patients with depression and anxiety and may be due to their underlying disease. The impact of mental illnesses on morbidity and mortality of COVID-19 patients remains unclear and requires further studies
Aspect oriented implementation of design patterns using metadata
Computer programming paradigms aim to provide better separation of concerns. Aspect oriented programming extends object oriented programming by managing crosscutting concerns using aspects. Two of the most important critics of aspect oriented programming are the “tyranny of the dominant signature” and lack of visibility of program's flow. Metadata, in form of Java annotations, is a solution to both problems. Design patterns are assumed as the general solutions for Object-Oriented matters. They assist in software complexity management and serve as a bridge among software designers as well. These properties have led the patterns to be introduced as a choice in order to prove new technologies. Successful implementations share a generic solution: the usage of annotation to configure and mark the participants, while the pattern's code is encapsulated in aspects. This loses the coupling between aspects and type signatures and between the code base and a specific AOP framework. Also, it increases the developer's awareness of the program's flow. In the present article, aspect oriented programming and design patterns are introduced and also taking the benefit of annotation equipment in java language is proposed as a solution to reduce tight coupling and increase program flow observation rate for aspect oriented programming. Keywords: aspect oriented programming, design patterns, object oriented programming, metadata
A Methodology for Performing Meta-analyses of Developers Attitudes Towards Programming Practices
Programming practices are often labelled as “best practice” and “bad practice” by developers. This label can be subjective but we can see trends among developers. A methodology for performing meta-analyses of articles discussing any given practice was created to determine programmers overall attitudes towards any given practice while accounting for factors such as whether they considered alternative approaches
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