On the Unit Graph of a Noncommutative Ring

Let $R$ be a ring (not necessary commutative) with non-zero identity. The unit graph of $R$, denoted by $G(R)$, is a graph with elements of $R$ as its vertices and two distinct vertices $a$ and $b$ are adjacent if and only if $a+b$ is a unit element of $R$. It was proved that if $R$ is a commutative ring and \fm is a maximal ideal of $R$ such that |R/\fm|=2, then $G(R)$ is a complete bipartite graph if and only if (R, \fm) is a local ring. In this paper we generalize this result by showing that if $R$ is a ring (not necessary commutative), then $G(R)$ is a complete $r$-partite graph if and only if (R, \fm) is a local ring and $r=|R/m|=2^n$, for some $n \in \N$ or $R$ is a finite field. Among other results we show that if $R$ is a left Artinian ring, $2 \in U(R)$ and the clique number of $G(R)$ is finite, then $R$ is a finite ring.Comment: 6 pages. To appear in Algebra Colloquiu

Exploring field scale salinity using simulation modeling, example for Rudasht area, Esfahan Province, Iran

Salinity / Simulation models / Soil-water-plant relationships / Soil properties / Climate / Irrigated farming / Water quality / Iran / Esfahan Province / Rudasht Area

A typology of community and stakeholder engagement based on documented examples in the field of novel vector control.

BackgroundDespite broad consensus on the importance of community and stakeholder engagement (CSE) for guiding the development, regulation, field testing, and deployment of emerging vector control technologies (such as genetically engineered insects), the types of activities pursued have varied widely, as have the outcomes. We looked to previous CSE efforts for clarity about appropriate methods and goals. Our analysis yielded a typology of CSE, and related vocabulary, that describes distinctions that funders, organizers, and scholars should make when proposing or evaluating CSE.MethodsWe compiled available formal documentation of CSE projects, starting with projects mentioned in interviews with 17 key informants. Major features of these examples, including the initiators, target groups, timing, goals, and methods were identified using qualitative coding. Based on these examples, subcategories were developed for a subset of features and applied to the identified cases of CSE in the documents. Co-occurrence of subcategorized features was examined for patterns.ResultsWe identified 14 documented examples CSE projects, which were comprised of 28 distinct CSE activities. We found no clear patterns with respect to timing. However, we found that grouping examples according to whether initiators or targets could enact the immediate desired outcome could help to clarify relationships between goals, methods, and targets.ConclusionBased on this analysis, we propose a typology that distinguishes three categories of CSE: engagement to inquire -where initiators are empowered to act on information collected through engagement with target groups; engagement to influence -where initiators engage to affect the actions of already-empowered target groups; and engagement to involve -where initiators engage to delegate authority to target groups. The proposed typology can serve as a guide for establishing the goals, identifying appropriate methods, and evaluating and reporting CSE projects by directing attention to important questions to be asked well before determining who to engage and how

Подземная река Ужла – примечательный феномен Русской равнины

Сообщение представляет историю исследования феномена реки и источника-воклюза Ужла в Вологодской области, а также итоги спелеоподводной экспедиции, проведенной в марте 2012 г. и посвященной изучению этого источника. Результатом экспедиции явилось обнаружение на глубине 64-66 метров (от зеркала воды в источнике) подземного русла реки Ужла – протяженной подводной пещеры.Повідомлення представляє історію дослідження феномену річки та джерела-воклюзу Ужла у Вологодській області, а також підсумки спелеопідводної експедиції, проведеної у березні 2012 р. і присвяченої вивченню цього джерела. Результатом експедиції стало виявлення на глибині 64-66 метрів (від дзеркала води в джерелі) підземного русла річки Ужла - протяжної підводної печери.This communication presents history of investigations of the phenomenon of the river and Vaucluse-type resurgence Uzhla in the Vologda region results of the speleo-diving expedition conducted in March 2012, aimed in studying of the resurgence. The result of expedition was a discovery of an underground river-bed of the river Uzhla – an extensive submarine cave at depth of 64-66 meters (from the water table at the source)

Pola Komunikasi Pencari Suaka Asal Afghanistan dalam Berinteraksi di Rumah Detensi Imigrasi Pekanbaru

The movement of people from one place to another is a common thing in todays times. Technology support and access to adequate transportation as well as the interests of the individual is the reason for the transfer to happen. Turbulent political conditions and trigger wars in some countries is one of the reasons for the immigration of people for seek asylum. Pekanbaru city is one of the cities that is much visited by immigrants with a reason to seeking asylum. Until September 2015 there were 300 people from different countries who inhabit the immigration detention center and of the number of 300 asylum seekers from Afghanistan were the most with 217 asylum seekers. they have to make any interactions with the other asylum seekers or the immigrants officers. The goal of this research is to analyze the communication patterns and to identify the verbal and nonverbal communication of the Afghanistan asylum seekers in the Immigration Detention Of Pekanbaru.This research used descriptive qualitative research metode, with the selection of informants using purposive sampling technique, which selects three informants, which is a KASUBSI Security of Immigration Detention Pekanbaru, and two Afghanistan asylum seekers. The data collection techniques are used observation, in-depth interviews, and documentation.While,for the data analysis was refer to the interactive model of Huberman and Miles. Then, for checking the validity of data were using extension participation and triangulation techniques.The results of this research are showed that the communication patterns of the Afghanistan asylum seekers are divided into two; the first one is internalcommunication pattern which uses all channels outline. In this pattern, they can make any interaction and it will influence each other. And then In this pattern of communication with external groups, the leader will come out of the loop all channels outline and served as a translator for the group members and external groups. In daily interaction, they use verbal communication in Parcy language or English with nonverbal communication such as facial, gestural, and postural message.Keyword: Communication pettern, Afghanistan Seekers Asylum, Immigration Detention of Pekanbar

On graphs whose star sets are (co-)cliques

AbstractIn this paper we study graphs all of whose star sets induce cliques or co-cliques. We show that the star sets of every tree for each eigenvalue are independent sets. Among other results it is shown that each star set of a connected graph G with three distinct eigenvalues induces a clique if and only if G=K1,2 or K2,…,2. It is also proved that stars are the only graphs with three distinct eigenvalues having a star partition with independent star sets

Causes of the failure of the state in Syria (2010-2019)

What broke out as the Arab Spring in Tunisia in 2010 stroke Egypt and shed its light on the Middle East, including Syria. During the first few days of demonstrations in Syria, the spring turned into a bloody fall and a full-scale civil war. Political-security crises and economic and social problems that had dominated the country during Assad's family rule left the state in deep defeat. Meanwhile, the arena of war turned into the scene of conflict between different political forces and their regional and international supporters, caused Syria to encounter immense foreign intervention. In this regard, this article attempts to figure out the answer to this question, "What are the causes for the Syrian state of failing during 2010-19?" The authors hypothesize that "the state in Syria has failed since the beginning of the protests due to persistent social, economic and political-security crises that led to the militarization of the country by the opposition and insurgent groups." The findings also indicate that the Syrian state faced historical crises after 2010 in economic imbalance and decline, demographic and environmental pressures, political-administrative corruption, and weak public services, which deepened after 2011, and it spread to other areas such as ethnic-religious violence

Effect of different levels of dietary betaine on growth performance, food efficiency and survival rate of pike perch (Sander lucioperca) fingerlings

A 6-week feeding experiments were carried out to determine the effects of different levels of dietary betaine on growth performance, food efficiency and survival rate of pike perch which has a critical period during transition feeding. Fingerlings of pike perch were fed with live food (treatment A), without betaine added to biomar (treatment B), 1% betaine added to biomar (treatment C) and 2% betaine added to biomar (treatment D) in 1000 l concreted tanks. 200 fingerlings (1.50 g, mean weight) were stocked in each tank and fed up to 7 meals per day. Higher increment in body weight (4.99 ± 0.73 g), specific growth rate (3.90 ± 0.06) and food efficiency (104.42 ± 4.27) were obtained with treatment D (2% betaine added to biomar). This treatment also showed significant (P<0.05) decrease in food conversion ratio (0.93 ± 0.04) in comparison with other treatments. Highest survival rate was observed in treatment B (biomar without betaine) with a 34.5 % rate and greatest cannibalism (1.03 ± 0.01) was found in treatment D, respectively. It was concluded that betaine could increase the palatability and acceptability of food and could be suitable to weaning the pike perch fingerlings to artificial diet