168 research outputs found

    On the Parameterized Complexity of Deletion to ?-Free Strong Components

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    Directed Feedback Vertex Set (DFVS) is a fundamental computational problem that has received extensive attention in parameterized complexity. In this paper, we initiate the study of a wide generalization, the H-SCC Deletion problem. Here, one is given a digraph D, an integer k and the objective is to decide whether there is a vertex set of size at most k whose deletion leaves a digraph where every strong component excludes graphs in the fixed finite family H as (not necessarily induced) subgraphs. When H comprises only the digraph with a single arc, then this problem is precisely DFVS. Our main result is a proof that this problem is fixed-parameter tractable parameterized by the size of the deletion set if H only contains rooted graphs or if H contains at least one directed path. Along with generalizing the fixed-parameter tractability result for DFVS, our result also generalizes the recent results of Göke et al. [CIAC 2019] for the 1-Out-Regular Vertex Deletion and Bounded Size Strong Component Vertex Deletion problems. Moreover, we design algorithms for the two above mentioned problems, whose running times are better and match with the best bounds for DFVS, without using the heavy machinery of shadow removal as is done by Göke et al. [CIAC 2019].publishedVersio

    Nitrogen and phosphorous budgets for integrated culture of whiteleg shrimp Litopenaeus vannamei with red seaweed Gracilaria corticata in zero water exchange system

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    In this study, a 2×3 factorial design with two levels of shrimp density (25 and 50 shrimp per m2) and three levels of red algae density (0, 200 and 400g per m2) was applied to calculate nitrogen and phosphorous budgets in the integrated culture of Litopenaeus vannamei with Gracilaria corticata during 45 days in a zero water exchange system. Juveniles of L. vannamei (5.82±0.11 g) and G. corticata were cultured in 18 round 1 m3 poly ethylene tanks. Water temperature, dissolved oxygen (DO), pH and salinity were measured once every 3 days. Results indicated that shrimp density had a significant effect on pH and DO in the morning and in the afternoon. The algal density didn’t have a significant effect on pH and DO in culturing tanks (p> 0.05). According to the results of this study, the main source of nitrogen and phosphorus input to the tanks during a 45-day culturing period was from feeds. Shrimp and algal densities significantly affect the concentration of total ammonia, nitrite, nitrate and phosphate in water and an increase in shrimp density led to an increase of these compounds whereas, increasing the algal density led to the reduction of these compounds. Results indicated that increasing the density of G. corticata in all treatments, led to an increase in biomass of harvested shrimp and the co-culture of G. corticata with L. vannamei decreased the amount of nitrogen and phosphorus in both water and sediments and improved the water quality of L. vannamei culture

    Brief Announcement: Treewidth Modulator: Emergency Exit for DFVS

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    In the Directed Feedback Vertex Set (DFVS) problem, we are given as input a directed graph D and an integer k, and the objective is to check whether there exists a set S of at most k vertices such that F=D-S is a directed acyclic graph (DAG). Determining whether DFVS admits a polynomial kernel (parameterized by the solution size) is one of the most important open problems in parameterized complexity. In this article, we give a polynomial kernel for DFVS parameterized by the solution size plus the size of any treewidth-eta modulator, for any positive integer eta. We also give a polynomial kernel for the problem, which we call Vertex Deletion to treewidth-eta DAG, where given as input a directed graph D and a positive integer k, the objective is to decide whether there exists a set of at most k vertices, say S, such that D-S is a DAG and the treewidth of D-S is at most eta

    Effect of illness perception improvement on risk factors of coronary artery disease

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    Background: Illness perception can affect health-related behaviors and disease outcomes. Objectives: To determine the effect of an educational intervention of improving illness perception on some modifiable risk factors of coronary artery disease. Methods: In this clinical trial, 100 patients undergoing coronary angiography that met the inclusion criteria were divided randomly into two intervention and control groups. In the intervention group, three educational sessions were conducted individually, while usual care was conducted for the control group. Measurements on fasting blood glucose, cholesterol, triglyceride, blood pressure, body mass index, and smoking status were gathered at baseline, immediately and six months after the intervention in both groups. Data were analyzed using the SPSS. Results: The mean of systolic blood pressure (p<0.005), fasting triglycerides (p<0.005), and fasting blood glucose (p<0.005) were significantly different before and after the intervention between the two groups. Conclusion: Improvement illness perception through educational intervention can affect risk factors of coronary artery disease

    Study on effects of physical, biological and chemical parameters on growth and bloom-forming of dinoflagellates Cochlodinium polykrikoides

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    The red tide, as a natural phenomenon, has been frequently occurred in the Persian Gulf and Oman Sea coastal waters. Harmful algal blooms of Cochlodinium polykricoiedes were first observed in August 2007 and coincided with massive aquatic organisms’ mortalities and have caused substantial economic losses and negative effects on the aquatic environment in the Persian Gulf. The objective of this study was to evaluate direct control or mitigation of C. polykricoiedes blooms through physical (flocculation with clay; 0.5, 1.0, 1.5, 2, 4 and 10 g L^-1), biological [6 seaweeds; fresh and extract (aqueous and methanol)] and chemical (hydrogen peroxide, potassium permanganate, copper sulfate, acetic acid and sodium hypochlorite; 0.05, 0.1, 0.5, 1 and 1.5 g L^-1) treatments. The results of the physical assay showed that the growth of C. polykricoiedes was strongly inhibited by using clay slurry in 4 or 10 g L^-1. The removal efficiency of C. polykricoiedes by clay was 99% after 24 hour. The seaweeds showed the most mitigation effect on C. polykricoiedes using aqueous extract was C. sinnosa, using mixed aqueous and methanol were S. illicifolium , U. lactuca and G. corticata, fresh tissue were E.intistialisی C.sinuosa, H.valentiea, and culture filtrate of E. intistialis. The results clearly showed that the flocculants; potassium permanganate, copper sulfate, acetic acid and sodium hypochlorite had the highest removal efficiency (100%) of C. polykricoiedes cells in the lowest concentration (0.05 g L^-1). Overall, our experiments suggest that using clay and seaweeds as a control strategies could be considered for HABs in the Persian Gulf coastal waters

    Determination of effective parameters on growth and bloom forming of Cochlodinium polykrikoides

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    Harmful algal blooms resulting in red discoloration of coastal waters in the Persian Gulf, Iran were first observed in January 2007. The species responsible for the bloom, which was identified as Cochlodinium polykrikoides, coincided with massive aquatic organisms’ mortalities in the Persian Gulf. In order to provide optimum growth and bloom forming, C. polykrikoides cells were sampled during the bloom conditions in the coastal waters of Persian Gulf. After adaptation in filtered seawater, they isolated by positive phototropism characteristic of this species to light. They were grown in modified media culture at different salinity (30, 32 and 35ppt), temperature (20, 23, 26 and 28ÂșC) and intensity (35, 70 and 90 ”mol m^-2 s^-1) with an initial cell density of 50 cell mL^−1. The results of the present study clearly showed that the highest alga biomass was obtained following culture by using A^2 medium under the 32ppt salinity, 26°C temperature, and under a 11h light:13h dark photoperiod regime at a light intensity of 90 ”mol m^-2 s^-1 provided by cool white fluorescent tubes. Mean cell density of C. polykrikoides in a 60 liter tank for ten days reached to 32 × 10^6 cell L^−1. Moreover, individual C. polykrikoides chain with 18 cells was observed for the first time in cultures. Based on the results from the present study, as mentioned above, providing suitable media culture and physical condition (light intensity and temperature), bloom forming of C. polykrikoides start from day 8 to 10 and will be continued until day 24 t0 28. In the other hand, C. polykrikoide cells immediately crashed and destroyed

    Egg production and larval rearing of orange-spotted grouper (Epinephelus coioides) using reared broodstocks in Hormozgan Province, Iran

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    Egg production of cultivated broodstocks of orange-spotted grouper, Epinephelus coioides and larvae rearing were surveyed in Iran from 2008 to 2012. Broodstocks were obtained by rearing of 7 wild juveniles (587.57 ± 132.63 g body weight) which were caught from the north of Persian Gulf in October 2008 and reared to December 2012. Captured juvenile fishes were fed using defrosted trash fish at a rate of 4-6 percent of body weight per day. Four-year-old fishes spawned spontaneously, when average weight of females and males were about 7020 ± 1277 g and 5128 ± 253g respectively. Effects of four temperature ranges (23-24, 26-27, 28-29 and 31-32 °C) and three tank size ( 40L, 300L and 2400L) on hatching and survival rates were examined. Eggs were stocked as a density of 25 Eggs L^-1. Effects of tank size on hatching rate and survival of larvae were assessed at 1, 5, 10, 20 and 30 days after hatching (DAH). The optimal temperature range for hatching was 28-29°C. No difference was observed among hatching rates of fish within the various tank sizes. Survival rates of larvae in 2400L fiber glass tanks until 30 days after hatching were significantly higher than the other tanks. Results indicate this species can be reproduced and reared in large numbers under normal rearing conditions and carefully controlled temperature

    Religious perspectives on withdrawal of treatment from patients with multiple organ failure

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    The document attached has been archived with permission from the editor of the Medical Journal of Australia (09 January 2008). An external link to the publisher’s copy is included.Religious or spiritual values often influence health care decision-making by patients and their families, particularly in times of crisis. Though religious values might seem to be irrelevant where continuing treatment is judged to be “futile”, such clinical assessments should instead serve to open a dialogue about values and beliefs. The six major religious traditions in Australia have some similar values and principles about death and provision of care for the dying, but differ in their processes of ethical reasoning, cosmologies, and key moral concepts. Engaging with religious traditions on the common ground of basic values (such as human dignity, care, the sacredness of human life, non-violence, compassion, and selflessness) promotes negotiation of the manner in which care is provided, even where conflicts exist.Rachel A Ankeny, Ross Clifford, Christopher F C Jordens, Ian H Kerridge and Rod Benso

    Studying native fishes in Hamadan province

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    Studying native fishes of Hamadan province have been done in 159 stations from 51 important water resources (wetland, reservoir, spring, river and qanat) using with electric tool, cast-net, seine and gill-net gears from July 2010 to Oct. 2011 and the main aims were species identifying and determining their distribution and abundance in the studied area. In the study, 33411 fish specimens are caught in 257 times of sampling and selected randomly about 8500 individual and laboratory works showed the fish belong to 37 species from 7 families. Cyprinidae with 25, Nemacheilidae with 6 and Sisoridae with 2 species had the most diversity and Cobitidae, Poeciliidae, Salmonidae and Mastacembelidae had only a representative. 31 fish species were native or endemic and 6 species were alien. Fish species existed in all rivers of Ghezelozan and Sirvan sub-basins but there were not any fish in 10 rivers of Ghara-Chai sub-basin and in 6 rivers of Gamasiab sub-basin, too. Also, it was observe 1-3 fish species in 15 rivers, 4-6 fish species in 10 rivers, 7-10 fish species in 5 rivers and more than 10 fish species in 4 main water resources and Gamasiab sub-basin with 32 fish species was the most diversified and Ghezelozan sub-basin with 2 fish species was the least diversified. There were any species to 4 (mostly 1 or 2) fish species in studied qanats in Ghara-Chai and Gamasiab rivers sub-basins. 23 fish species existed in a subbasin, 12 species in 2 sub-basin, Capoeta capoeta in 3 sub-basin and Squalius cephalus in all sub-basins of studied area. Alburnoides nicolausi,Capoeta aculeata and Alburnus mossulensis have had the most frequency. Studying fish abundance showed Oxynoemacheilus argyrogramma with 17.8%, Garra rufa with 12.3%, A. mossulensis with 12.1% and C. aculeata with 10.2 % of total number of caught fish specimens are dominant. S. cephalus, Capoeta damascina, C. aculeata, C. trutta, Chondrostoma regium and A. mossulensis have had sport fishing value but Acanthobrama marmid, Oxynoemacheilus kiabii, Oxynoemacheilus kermanshahensis, Turcinoemacheilus kosswigi, Alburnus caeruleus and Mastacembelus mastacembelus have biodiversity value for being endemic or having limited habitats in Iran

    Production of nanoparticles from natural hydroxylapatite by laser ablation

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    Laser ablation of solids in liquids technique has been used to obtain colloidal nanoparticles from biological hydroxylapatite using pulsed as well as a continuous wave (CW) laser. Transmission electron microscopy (TEM) measurements revealed the formation of spherical particles with size distribution ranging from few nanometers to hundred nanometers and irregular submicronic particles. High resolution TEM showed that particles obtained by the use of pulsed laser were crystalline, while those obtained by the use of CW laser were amorphous. The shape and size of particles are consistent with the explosive ejection as formation mechanism
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