Seeding with Costly Network Information

We study the task of selecting $k$ nodes in a social network of size $n$, to seed a diffusion with maximum expected spread size, under the independent cascade model with cascade probability $p$. Most of the previous work on this problem (known as influence maximization) focuses on efficient algorithms to approximate the optimal seed set with provable guarantees, given the knowledge of the entire network. However, in practice, obtaining full knowledge of the network is very costly. To address this gap, we first study the achievable guarantees using $o(n)$ influence samples. We provide an approximation algorithm with a tight (1-1/e){\mbox{OPT}}-\epsilon n guarantee, using $O_{\epsilon}(k^2\log n)$ influence samples and show that this dependence on $k$ is asymptotically optimal. We then propose a probing algorithm that queries ${O}_{\epsilon}(p n^2\log^4 n + \sqrt{k p} n^{1.5}\log^{5.5} n + k n\log^{3.5}{n})$ edges from the graph and use them to find a seed set with the same almost tight approximation guarantee. We also provide a matching (up to logarithmic factors) lower-bound on the required number of edges. To address the dependence of our probing algorithm on the independent cascade probability $p$, we show that it is impossible to maintain the same approximation guarantees by controlling the discrepancy between the probing and seeding cascade probabilities. Instead, we propose to down-sample the probed edges to match the seeding cascade probability, provided that it does not exceed that of probing. Finally, we test our algorithms on real world data to quantify the trade-off between the cost of obtaining more refined network information and the benefit of the added information for guiding improved seeding strategies

The frequency and risk factors of Helicobacter pylori in children of 6 years old from Shahrekord in 2006

چکیده: زمینه و هدف: هلیکوباکتر پیلوری یکی از عفونت های شایع در انسان است که در ایجاد گاستریت حاد و مزمن، زخم پیتیک و سرطان معده نقش دارد. شیوع عفونت در کودکی 10 تا 80 درصد بوده و بیشترین شیوع در کشورهای در حال توسعه می باشد. هدف از این مطالعه، تعیین میزان آلودگی به هلیکوباکتر پیلوری در کودکان شش ساله شهرکرد و عوامل موثر بر آن بوده است. روش بررسی: در این مطالعه توصیفی – تحلیلی تعداد 215 نفر از کودکان 6 ساله مراجعه کننده برای طرح سنجش کودکان بدو ورود به دبستان شهرکرد وارد مطالعه شدند. نمونه مدفوع جمع آوری و با استفاده از روش ELISA از نظر آنتی ژن هلیکوباکترپیلوری بررسی گردید. داده ها با استفاده از آزمون های آماری کای دو و رگرسیون لجستیک مورد تجزیه و تحلیل قرار گرفتند. یافته ها: بر اساس نتایج 3/23 (50 مورد) از نمونه ها از نظر آنتی ژن هلیکوباکترپیلوری مثبت بودند. شیوع عفونت هلیکوباکترپیلوری رابطه معنی داری با جنس، مصرف سیگار والدین، درد شکم، رشد، تهوع، بی اشتهایی، زخم معده و یا اثنی عشر در والدین و سابقه استفاده از شیر مادر نداشت. ولی با تحصیلات والدین و سابقه سرطان معده در فامیل درجه اول رابطه معنی داری وجود داشت (05/0

Cerebral Protection During Coronary Artery Bypasses Grafting in Bilateral Total Internal Carotids Occlusion: Case Report

Introduction: The best management for the patient with coronary artery disease (CAD) that requires emergent coronary bypass graft surgery (CABG) with bilateral total internal carotid artery occlusions previously reported. Here we report two successful cases of CABG with additional occlusion in the circle of Willis anterior or posterior communicating artery “incomplete cow” with onpump technique and cerebral protection considerations. Case Presentation: Bilateral carotid artery occlusion, coronary artery disease, and emergency operation with cardiopulmonary bypass are associated with increased stroke, especially when there is one additional occlusion of the cerebral artery in the circle of Willis. Routine preoperative carotid artery sonography and selective carotid angiography revealed bilateral total carotid occlusion in both cases in addition, CT-angiography also confirmed occlusions of right posterior communicating in the first case and left posterior communicating artery in the second case. Collateral circulation feeding in the intracranial circulations originated mainly from the vertebrobasilar system (compensatory phase) preoperative physical examinations showed no neurological deficit. Operation was done successfully with moderate hypothermia and different cerebral protection considerations and postoperative courses were uneventful and patients discharged from hospital seven days post operation. Conclusions: Anesthesia should consider hemodynamic management and avoid significant tachycardia or bradycardia and severe hypertension or hypotension

Determination of fecal Alpha 1-Antitrypsin as marker for differentiation of microbial and non-microbial diarrhea

Alpha-1 anti-trypsin=AAT) یکی از پروتئین های فاز حاد سرم انسان است که سطوح سرمی آن در بعضی از بیماری ها از جمله بیماری های کبدی، کلیوی و ریوی تغییر می یابد و متعاقب اختلالات گوارشی از جمله اسهال، AAT از طریق مدفوع دفع می شود. اندازه گیری AAT مدفوع در تشخیص دفع غیر طبیعی پروتئین مورد استفاده قرار گرفته است. در مطالعات مختلفی، میزان AAT مدفوع به عنوان شاخص در تشخیص افتراقی انواع اختلالت گوارشی اندازه گیری شده است. باتوجه به اینکه تشخیص افتراقی اسهال های میکروبی از غیر میکروبی به علت نیاز به انجام کشت مدفوع وقت گیر می باشد لذا در این مطالعه سنجش میزان AAT مدفوع به عنوان یک آزمایش غربالی اولیه برای متمایز نمودن انواع اسهال ها (عفونی باکتریال و غیر عفونی) مورد مطالعه قرار گرفته است. در این مطالعه مورد-شاهدی مقدار AAT مدفوع کودکان بستری شده در بخش اطفال بیمارستان هاجر شهرکرد اندازه گیری شد. گروه اول شامل 30 کودک مبتلا به اسهال بودند که نتیجه کشت مدفوع آنها از نظر میکروبی مثبت و گروه دوم شامل 30 کودک مبتلا به اسهال بودند که نتیجه کشت مدفوع آنها از نظر میکروبی منفی بوده است و گروه شاهد شامل 30 کودک غیر مبتلا به اسهال بود. در تمام کودکان فوق میزان AAT مدفوع به روش رادیال ایمونودیفیوژن اندازه گیری گردید. میانگین مقدار AAT در گروه اول mg/dl 46.2±50، در گروه دوم mg/dl 34.77±25 و در گروه شاهد (افراد سالم) mg/dl 3.35±1.08 می باشد. از نظر آماری میانگین AAT در سه گروه اختلاف معنی داری نشان داد. نتایج این بررسی نشان داد که میانگین مقدار AAT در گروه مبتلا به اسهال و دارای کشت میکروبی مثبت (گروه اول) بالاتر از سایر گروه ها بوده است. اما در سطح انفرادی تمام افراد این گروه میزان AAT بالایی نداشتند. لذا پیشنهاد می گردد در مطالعه تکمیلی میزان AAT مدفوع در مقایسه با میزان AAT سرم اندازه گیری گردد

In-vitro effect of menthe piperita and salvia officinalis extracts on trichomonas vaginalis

Background: Trichomonas vaginalis is a flagellate parasite causing vaginosis, a common sexual transmitted disease. Metronidazole is the drug of choice for this disease but due to its side effects, it is necessary to search for an alternative drug. In this study, the effect of Menthe piperita and Salvia officinalis on Trichomonas vaginalis was investigated. Methods: Hydro-alcoholic extracts of the two herbs were prepared. The extracts were dried using vacuum rotary evaporator. Different concentrations of the extracts in comparison with methronidazole were added in test tubes containing culture medium and the parasite. All test tubes were kept in 37°C for 24 hours. The tubes were then expected for the parasite growth. Findings: In concentrations of 2, 2.5, 4, 5, 8, and 10 mg/ml of Salvia officinalis and in concentrations of 4, 5, 8, and 10 mg/ml of Menthe piperita the parasite did not grow. The effect of the extracts on Trichomonas vaginalis was similar to the effect of metronidazole on the parasite. Conclusion: Salvia officinalis and Menthe piperita had efficient effect against Trichomonas vaginalis growth in culture medium and s,o these two herbs can be considered as alternatives drugs. However, more investigation is recommended

Reliable and specific detection and identification of Brenneria goodwinii, the causal agent of oak and oriental beech decline

Chestnut-leaved oak (Quercus castaneifolia) and oriental beech (Fagus orientalis) are among the major tree species in the Hyrcanian forests. Brenneria goodwinii was identified as the causal agent of necrotic lesions and stem bleeding on affected oak trees in different countries. Oak and oriental beech trees with bleeding symptoms were observed in a few forest sites in northern Iran. The objectives of the present study were to identify and characterize the causal agents of bark canker in oak and oriental beech trees and develop a primer set for specific detection, using polymerase chain reaction (PCR), of Brenneria goodwinii strains. A total of 31 and 20 samples from oak and oriental beech trees, respectively, with stem bleeding and bark canker symptoms were collected from Golestan and Mazandaran forests in northern Iran in 2020–2021. Bacterial strains displaying a green metallic sheen on EMB-agar medium were isolated from symptomatic oak (105 strains) and oriental beech samples (32 strains), while 31 and 20 strains were also isolated from healthy oak and oriental beech, respectively. Pathogenicity tests indicated that 51 and 25 strains isolated from oak and oriental beech, respectively were able to induce a necrotic area on oak acorns 15 days following inoculation. Moreover, four and two representative strains inoculated on oak and oriental beech twigs, respectively induced necrosis on all inoculated green twigs 1 month after inoculation. The sequences of the 16S rRNA and gyrB genes of representative strains isolated from and proved pathogenic on oak and oriental beech trees were 100% and over 99% similar to B. goodwinii LMG 26270T, respectively, which revealed the strains belong to B. goodwinii species. The primer pair BgF3/R2, which was designed to target the hrpN gene, was proven to be specific in the detection of B. goodwinii strains. The primer pair amplified a 618-bp DNA fragment from strains of B. goodwinii only and not from strains belonging to Rahnella, Gibbsiella, Lonsdalea, and the other Brenneria species among several other pathogenic bacteria tested. No fragment was amplified from DNA extracted from healthy trees or seedlings in PCR using this primer pair

Assessment of teacher performance in a private Iranian high school using the North Carolina teacher performance appraisal instrument

This study assessed teachers' performance in a private Iranian high school using the Teacher Performance Appraisal Instrument (TPAI) of North Carolina. The teacher performance appraisal system was used to: 1) determine levels of competency, 2) improve performance, 3) validate strong performance, 4) professional growth plans, 5) identify areas needing improvement, 6) licensure, 7) document problems areas 8) accurately reflect performance, and 9) self assessment. In this study, a team of researchers scrutinized and assessed school teachers' performance in class. There were 31 teachers and they were assessed based on 8 major functions, further defined by 43 indicators. According to the findings, the teachers of the high school were divided into three groups: 1) teachers who mastered new instructional methods and had more than 10 years experience in teaching 2) teachers with 5 to 10 years of experience and 3) student teachers with less than 5 years background. The performance level of the first group was high in a majority of the functions. The performance level of the second group was high in some of the major functions and the third group showed low performance in a majority of the functions

Virulence factors of Helicobacter pylori vacA increase markedly gastric mucosal TGF-beta 1 mRNA expression in gastritis patients

Objective: Helicobacter pylori (H. pylori) infection is the main cause of gastric inflammation. Regulatory T cells (Treg cells) suppress the activation and proliferation of antigen-specific T cells and mediate immunologic tolerance. TGF-beta 1 was shown to be secreted in a subset of Treg cells known as `Th3 cells'. These cells have not been sufficiently studied in context to H. pylon-induced inflammation in human gastric mucosa. In this study we therefore, aimed to investigate the expression of TGF-beta 1 in the context of H. pylori colonization in chronic gastritis, to examine the relationship between it and histopathologic findings and to compare it with virulence factors. Patients and methods: Total RNA was extracted from gastric biopsies of 48 H. pylori-infected patients and 38 H. pylori-negative patients with gastritis. Mucosal TGF-beta 1 mRNA expression in H. pylori-infected and uninfected gastric biopsies was determined by real-time PCR. Presence of vacA, cagA, iceA, babA2 and oipA virulence factors was evaluated using PCR. Results: TGF-beta 1 mRNA expression was significantly increased in biopsies of H. pylori-infected patients compared to H. pylori-uninfected patients. There was association between virulence factors and TGF-beta 1 mRNA expression. TGF-beta 1 mRNA expression in mucosa was significantly higher in patients with vacA s1 and s1m1. Conclusions: TGF-beta 1 may play an important role in the inflammatory response and promote the chronic and persistent inflammatory changes in the gastric. This may ultimately influence the outcome of H. pylon-associated diseases that arise within the context of gastritis and vacA may suffice to induce expression of TGF-beta 1 mRNA. (C) 2014 Elsevier Ltd. All rights reserved

Frequency of virulence factors in Helicobacter pylori-infected patients with gastritis

The outcome of Helicobacter pylori infection has been related to specific virulence-associated bacterial genotypes. The vacuolating cytotoxin (vacA), cagA gene, oipA and babA2 gene are important virulence factor involving gastric diseases. The objective of this study was to assess the relationship between virulence factors of H. pylori and histopathological findings. Material and methods: Gastroduodenoscopy was performed in 436 dyspeptic patients. Antrum biopsy was obtained for detection of H. pylori, virulence factors and for histopathological assessment. The polymerase chain reaction was used to detect virulence factors of H. pylori using specific primers. Results: vacA genotypes in patients infected with H. pylori were associated with cagA, iceA1 and iceA2. In the patients with H. pylori infection there was a significant relationship between cagA positivity and neutrophil activity (P = 0.004) and chronic inflammation (P = 0.013) and with H. pylori density (P = 0.034). Neutrophil infiltration was found to be more severe in the s1 group than in the s2 group (P = 0.042). Also was a significant relationship between oipA positivity and neutrophil activity (P = 0.004) and with H. pylori density (P = 0.018). No significant relationships were observed between other vacA genotypes and histopathological parameters. Conclusion: H. pylori strains showing cagA, vacA s1 and oipA positivity are associated with more severe gastritis in some histological features but virulence factors of H. pylori do not appear to determine the overall pattern of gastritis. (C) 2015 Elsevier Ltd. All rights reserved