265 research outputs found

    Thermodynamic curvature and black holes

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    I give a relatively broad survey of thermodynamic curvature RR, one spanning results in fluids and solids, spin systems, and black hole thermodynamics. RR results from the thermodynamic information metric giving thermodynamic fluctuations. RR has a unique status in thermodynamics as being a geometric invariant, the same for any given thermodynamic state. In fluid and solid systems, the sign of RR indicates the character of microscopic interactions, repulsive or attractive. R|R| gives the average size of organized mesoscopic fluctuating structures. The broad generality of thermodynamic principles might lead one to believe the same for black hole thermodynamics. This paper explores this issue with a systematic tabulation of results in a number of cases.Comment: 27 pages, 10 figures, 7 tables, 78 references. Talk presented at the conference Breaking of Supersymmetry and Ultraviolet Divergences in extended Supergravity, in Frascati, Italy, March 27, 2013. v2 corrects some small problem

    Quality management of cut carnation 'Tempo' with 1- MCP

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    Water relation and chlorophyll content are two important factors on the postharvest quality of cut flowers. 1-MCP (1–methylcyclopropene), as a gaseous inhibitor of ethylene action, significantly delayed the wilting ofcut carnation (Dianthus caryophyllus L.). The effects of 1-MCP depends on concentration, time duration and temperature. In this study, the effect of different 1-MCP concentrations (0, 20, 40, 60, 80 and 100 nl l-1) andtime durations (3, 6 and 9 h) on the vaselife, water uptake, loss of fresh weight and chlorophyll index of cut carnation 'Tempo' which is an ethylene-sensitive flower, were evaluated. The effects of 1-MCP concentrations and interaction between 1-MCP concentration and time duration on the vaselife, water uptake, loss of chlorophyll index and loss of fresh weight, were significant at 1% levels of probability. Also the effect of time duration on the loss of chlorophyll index and loss of fresh weight was significant at 5%and on the water uptake was significant at 1% of probability. Treatment with 60 nl l-1 1-MCP for 3 h with 16.47 days vaselife, 2.57 ml g-1 fresh weight, 2.41 ml g-1 water uptake and 2.667 loss of chlorophyll index wasbetter than other treatments

    Effect of Nano-Iron Chelate and Cycocel on Growth Parameters of Poinsettia

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    IntroductionPoinsettia (Euphorbia pulcherrima) from the family Euphorbiaceae is used as potted and cut flower and has great importance in floriculture industry. Appropriate application of nutrients and plant growth regulators has an important role in increasing the quantity and quality of crops. The successful application of various nanoplatforms in medicine under in vitro conditions has generated some interest in agro-nanotechnology. This technology holds the promise of controlled release of agrochemicals and site-specific targeted delivery to improve efficient nutrient utilization and enhanced plant growth. Nanoencapsulation shows the benefit of more efficient use and safer handling of pesticides with less exposure to the environment. Thus, nanofertilizers can be substituted for conventional fertilizers. The role of iron in the activity of some enzymes such as catalase, peroxidase and cytochrome oxidase has been demonstrated. Iron is present as a cofactor in the structure of many enzymes. The results of some studies showed that in the absence of micro-nutrients elements, the activity of some antioxidant enzymes decreased, which resulted in increased sensitivity of plants to environmental stresses. The use of nano-iron fertilizer is an appropriate solution to remove this problem. Some growth retardants such as cycocel, paclobutrazol, bayleton and daminozide reduced the plant growth. Growth reduction in some ornamental plants enhances their overall quality and marketing. Cycocel is one of the most important growth retardants which inhibits gibberellin biosynthesis and activity in plant. Today, a range of artificially made growth-reducing compounds are used in the floriculture industry. The effect of plant growth retardants, depends on the time and method of application, concentration, species and varieties type, type of target organ and environmental and physiological conditions. Plant growth retardants reduce the division and elongation of stem cells. These compounds also reduce stem length and growth by having a negative effect on gibberellin structure. Therefore, the present study investigated the effect of different levels of nano-iron fertilizer and different concentrations of cycocel on growth and development of poinsettia (Euphorbia pulcherrima Willd.). Materials and Methods These experiments were carried out based on a randomized completely block design in three replications to evaluate the effect of various levels of nano iron chelated fertilizer and cycocel on growth parameters of Euphorbia pulcherrima. Cuttings with a height of 15 to 20 cm, each with 3 nodes, were prepared from the mother plant of poinsettia. Cuttings were placed in water within 24 hours for exudation of latex. Then, cuttings were planted in perlite for rooting. After rooting (60-65 days), cuttings were transferred into substrates including cocopeat, municipal compost and soil in ratio of 1:1:1. Poinsettia cuttings were grown in pots. Treatments include nano-iron fertilizer (0, 0.9, 1.8, 3.6 and 4.5 g.l–1) and cycocel (0, 500, 1000, 1500 and 3000 mg.l–1). Application of EDTA-based nano-iron chelate as foliar spray was performed on plants at the beginning of the experiment and 30 days later, as well as the use of cycocel 30 days after the start of the experiment as foliar spray. Stem height, internode length, node number, root length, root number, root volume, leaf number, leaf surface, leaf total chlorophyll content, iron content in leaf and the number and longevity of bracts were evaluated. Results and Discussion Results showed that the lowest plant height and the highest leaf number, root length, root volume, the number and longevity of bracts were obtained in treatments of 1.8 g.l–1 nano-iron chelate without or with the concentration of 1000 mg.l–1 cycocel. In some traits such as root volume and chlorophyll content, the minimum amount was calculated in the maximum of nano-iron chelate and cycocel concentrations. Suitable root characters were severely reduced through the use of 3000 mg.l–1 cycocel. Overall, the most suitable treatment, especially for reduction of stem height and enhancing some vegetative traits (such as leaf number) and flowering (such as bract longevity) was 1.8 g.l–1 nano-iron chelate along with 1000 mg.l–1 cycocel. Research has demonstrated that cycocel application reduces plant height in various species, including ornamental plants, as confirmed by this study. Furthermore, this study reveals a novel effect of cycocel: it alters the weight of both aerial and underground plant parts, alongside influencing leaf iron and chlorophyll content. Notably, plant growth retardants like cycocel are known to increase cytokinin content, which in turn can lead to elevated leaf chlorophyll levels

    Fitting the integrated Spectral Energy Distributions of Galaxies

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    Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

    Effect of Glucose, Fructose, and Sucrose on Vase Life, Antioxidants Enzymes, and Some Physiologic Parameters of Carnation cv. ‘Yellow Candy’ Cut Flower

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    Introduction  Carnation (Dianthus caryphyllus L.), from Caryophyllaceae family, is one of the most important cut flowers in the world that its short vase life reduces the economic value. Postharvest longevity of cut flowers can be prolonged using carbohydrates (sugars) in a vase jar. Cut flowers undergo some physiological and biochemical changes that often lead to an early senescence. To delay the aging process in cut flowers, it is necessary to evaluate many aspects of preparation for storage conditions, especially preservative solutions that affect the quality and longevity of these flowers. Many flowers are harvested before they are fully developed, to ensure a long postharvest life and to minimize mechanical damages that might occur during handling. The growth and development of flower buds on cut flowers require food (especially carbohydrates), which is stored in the leaves and stems. These stored carbohydrates can be mobilized for the flower bud to use but maybe they are insufficient when the buds are harvested at a tight-bud stage. To maintain metabolic activities, including respiration, even for cut flowers that have reached full development, it is necessary to provide adequate reserves to achieve acceptable postharvest life. When stored materials are low, leaves and flowers age faster and the petals fade. Under these conditions, supplements can be provided to the flowers by adding sugars such as glucose, fructose and sucrose to the vase solutions. However, it is important to note that a sugar solution is also suitable for the growth of microorganisms, so that an antimicrobial agent should be added to the vase solution as well. Many researches were carried out on prolonging the vase life of cut carnation flowers with different preservative solutions together with an antimicrobial agent. Studies on postharvest longevity of cut carnation flowers using sugars as preservative solutions is low. Therefore, the aim of the present study was to evaluate the effect of sugars (glucose, fructose and sucrose) and application time on vase life and some physiological parameters of carnation cv. ‘Yellow Candy’ cut flowers. Materials and Methods  A factorial experiment based on completely randomized design in three replicates was performed in order to investigate the effect of different levels (0, 50 and 100 g/L) of three types of sugars (glucose, fructose, and sucrose) and two sugar application times (the first and second 24 h, on 2019) on vase life of carnation cv. ‘Yellow Candy’ cut flowers. Some other traits such as water uptake, dry mater, relative fresh weight, protein and carotenoid of petal, leaf chlorophyll, POD and SOD enzymes activity and MDA were also measured. The statistical analysis of data was performed using Statistical Package for Social Sciences (SPSS) v 16.0. Least significant difference (LSD) test at P < 0.05 was used to find out the significance of differences among the mean values.     Results and Discussion Results showed that the effect of different levels of sugars on all evaluated traits was significant. Each three levels of sugars at each two applied times caused to increase vase life and relative traits. Maximum vase life (18 days) was obtained in 50 g/L glucose at the first 24 h with no statistically significant differences with the 100 g/L sucrose and fructose at the first 24 h. The highest water uptakes and dry matter, the lowest POD and SOD activity and minimum MDA were obtained in treatment of 50 g/L glucose at the first 24 h. The study found that the highest levels of petal protein content, chlorophyll a, b, and total chlorophyll were achieved in carnation "Yellow Candy" cut flowers treated with 50 g/L glucose after 24 hours of harvesting. The application of sugars at the first 24 hours after harvesting had a greater impact on improving the vase life of the flowers compared to the second 24 hours. Therefore, the use of glucose as an external holding solution, preferably within the early hours of harvesting, is recommended to prolong the postharvest life of carnation "Yellow Candy" cut flowers. The study also revealed that the use of external holding solutions, particularly sugars combined with antimicrobial agents, can have a positive effect on prolonging the vase life of cut flowers. The concentration of sugar required in the holding solution varies depending on the type of flower being treated, with most flowers requiring a concentration of 2% sugar. However, some flowers may require higher concentrations, up to 4-6%, while others may be damaged if treated with concentrations higher than 1%. The application of sucrose has been shown to increase glucose and fructose levels in petals, further supporting the use of external holding solutions containing sugars for extending the vase life of cut flowers. Therefore, it is important to examine each flower before treating it to determine the optimal concentration of sugars. Sugars are a source of energy and carbon for cut flowers and play an important role in decreasing the protein degradation and ethylene production, maintenance of osmotic balance, increasing water uptake, and finally delaying in senescence proces

    Factors influencing behavioral intentions to use conditionally automated vehicles

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    Background: This study explored factors influencing the acceptance of conditionally automated vehicles among Australian drivers by extending the Technology Acceptance Model with the Technology Readiness Index. Method: Data from an online survey of 844 participants were analyzed using partial least squares structural equation modeling (PLS-SEM). Results: Perceived usefulness had the strongest direct effect on behavioral intention (0.469, p &lt; 0.001), followed by attitude (0.318, p &lt; 0.001). Innovativeness positively influenced behavioral intention (0.183, p &lt; 0.001), while insecurity had a negative impact (−0.071, p &lt; 0.01). Optimism and discomfort were not significant. Perceived usefulness also had significant indirect effects through attitude (0.156, p &lt; 0.001) and trust (0.072, p &lt; 0.001). Perceived ease of use indirectly influenced behavioral intention through perceived usefulness (0.306, p &lt; 0.001), attitude (0.102, p &lt; 0.001), trust (0.047, p &lt; 0.001), and their combinations. Trust indirectly affected behavioral intention via attitude (0.130, p &lt; 0.001). Perceived security and privacy risks had indirect negative effects through trust and attitude (−0.035, p &lt; 0.001; −0.005, p &lt; 0.05). Conclusion: These results suggest that fostering acceptance among less tech-savvy individuals may help promote positive attitudes, increase conditionally automated vehicle adoption, and potentially enhance road safety. Practical implications: These findings suggest a need for targeted programs to enhance perceived usefulness and trust while addressing security and privacy concerns, ultimately contributing to safer road systems through the adoption of conditionally automated vehicles

    Assessment of genetic diversity among some Iranian hazelnut genotypes using SSR markers

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    Abstract Studying genetic diversity is a preliminary step for conservation and utilization of germplasm. Talesh hills, located in Guilan province in northern part of Iran, are one of the main areas for natural distribution of hazelnut (Corylus avellana L.). Hazelnut trees in Talesh Mountains are a wild population (land race) and obtained from open-pollinated seedling. In this research, a population including 90 hazelnut samples was studied using 15 microsatellite markers. Totally, 98 polymorphic alleles were detected with an average of 6.53 alleles per locus. The lowest numbers of 3 alleles were observed in CaC-B005 and CaC-C114 and the highest number of 12 alleles in CaC-C101 locus. The average effective number of alleles (3.75), mean expected heterozygosity of (He=0.70) and average observed heterozygosity of (Ho=0.62) were estimated for studied loci. All loci showed high PIC with an average of 0.72 that the highest amount detected in CaC-B011 and CaC-B101 loci with values of 0.85 and 0.84, respectively. A dendrogram was generated by UPGMA clustering method that placed the 90 accessions into 7 main loose groups. According to the results a high genetic diversity was found in the studied population that mainly related to the hazelnut pollination nature that shows sporophytic incompatibility system enhancing out-crossing in natural populations

    Breast conserving surgery versus mastectomy: cancer practice by general surgeons in Iran

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    BACKGROUND: There appear to be geographical differences in decisions to perform mastectomy or breast conserving surgery for early-stage breast cancer. This study was carried out to evaluate general surgeons' preferences in breast cancer surgery and to assess the factors predicting cancer practice in Iran. METHODS: A structured questionnaire was mailed to 235 general surgeons chosen from the address list of the Iranian Medical Council. The questionnaire elicited information about the general surgeons' characteristics and about their work experience, posts they have held, number of breast cancer operations performed per year, preferences for mastectomy or breast conserving surgery, and the reasons for these preferences. RESULTS: In all, 83 surgeons returned the completed questionnaire. The results indicated that only 19% of the surgeons routinely performed breast conserving surgery (BCS) and this was significantly associated with their breast cancer case load (P < 0.01). There were no associations between BCS practice and the other variables studied. The most frequent reasons for not performing BCS were uncertainty about conservative therapy results (46%), uncertainty about the quality of available radiotherapy services (32%), and the probability of patients' non-compliance in radiotherapy (32%). CONCLUSION: The findings indicate that Iranian surgeons do not routinely perform BCS as the first and the best treatment modality. Further research is recommended to evaluate patients' outcomes after BCS treatment in Iran, with regard to available radiotherapy facilities and cultural factors (patients' compliance)

    A comparison of oral omeprazole and intravenous cimetidine in reducing complications of duodenal peptic ulcer

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    BACKGROUND: Gastrointestinal bleeding is a common problem and its most common etiology is peptic ulcer disease. Ulcer rebleeding is considered a perilous complication for patients. To reduce the rate of rebleeding and to fasten the improvement of patients' general conditions, most emergency departments in Iran use H2-blockers before endoscopic procedures (i.e. intravenous omeprazole is not available in Iran). The aim of this study was to compare therapeutic effects of oral omeprazole and intravenous cimetidine on reducing rebleeding rates, duration of hospitalization, and the need for blood transfusion in duodenal ulcer patients. METHODS: In this clinical trial, 80 patients with upper gastrointestinal bleeding due to duodenal peptic ulcer and endoscopic evidence of rebleeding referring to emergency departments of Imam and Sina hospitals in Tabriz, Iran were randomly assigned to two equal groups; one was treated with intravenous cimetidine 800 mg per day and the other, with 40 mg oral omeprazole per day. RESULTS: No statistically significant difference was found between cimetidine and omeprazole groups in regards to sex, age, alcohol consumption, cigarette smoking, NSAID consumption, endoscopic evidence of rebleeding, mean hemoglobin and mean BUN levels on admission, duration of hospitalization and the mean time of rebleeding. However, the need for blood transfusion was much lower in omeprazole than in cimetidine group (mean: 1.68 versus 3.58 units, respectively; p < 0.003). Moreover, rebleeding rate was significantly lower in omeprazole group (15%) than in cimetidine group (50%) (p < 0.001). CONCLUSION: This study demonstrated that oral omeprazole significantly excels intravenous cimetidine in reducing the need for blood transfusion and lowering rebleeding rates in patients with upper gastrointestinal bleeding. Though not statistically significant (p = 0.074), shorter periods of hospitalization were found for omeprazole group which merits consideration for cost minimization

    Impact assessment of master plan of "attain to technical knowledge of specific pathogen free shrimp production and cut off to dependence on foreign products" on Bushehr city environment: A case study, Shoghab research station

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    This study is a part of the national and technology master plan entitled "Attain to technical knowledge of specific pathogen free shrimp production and cut off to dependence on foreign products". The goals of this work were to assess the environmental effects of Specific Pathogen Free shrimp production complex on surrounded region in Persian Gulf (Shoghab) research station in Bushehr city. The environmental impacts were assessed in Bandragah research station in Bushehr city by usage of comprehensive method for impacts prediction, and Pastakia Matrix for assessment during Feb 2012 till Sep 2014. Results showed 8 negative and 3 positive environmental factors that affect by operating phase including 48% very slightly negative and 44.5% slightly positive and 7.5% very slightly positive effects. Although there is no significant different between negative and positive effects but based on national strategy on getting the technology doing such a projects is highly recommended. By the usage of technical methods in effluents treatment control and reduction of bad impacts is achievable
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