140 research outputs found

    Study of the Effects of Acidic Ions on Cloud Droplet Formation Using Laboratory Experiments

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    AbstractAtmospheric aerosols affect climate of the Earth, scatter sunlight and serve as cloud condensation nuclei (CCN). Yet the reason for many observed events of new aerosol formation is not understood. One of the ideas put forward to explain these events is that the presence of SO42- can enhance the formation of aerosols. These sulphate aerosols form partly during the oxidation of the oceanic emission Dimethyl sulfide (DMS) into the atmosphere and partly from volcanoes, plants and soils, fossil fuel combustion, and biomass burning. In this paper, laboratory experiments on warm cloud formation with different acid ion density are presented. The results show that the lifetime of cloud is reduced by increasing density of SO42-, but this changes is not significant (significance level, P=0.578), while the cloud concentration is significantly changed with the decreasing of density of SO42- (P=0.001). There is also a good significant correlation between cloud concentration with the maximum temperature change, with correlation coefficient, r=0.646 (p=0.004)

    Dissociation Between Attention and Consciousness During a Novel Task: an ERP Study

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    While consciousness and attention seem to be tightly connected, recent evidence has suggested that one of these processes can be present in the absence of the other. Recent researches showed that observers can pay attention to an invisible (unconscious) stimulus, and that a stimulus can be clearly perceived (seen) in the absence of attention. We have proposed a novel psychophysical task to explore neural correlates of top-down attention and consciousness. The task is meant to confirm that these two processes can occur independently of each other. EEG was recorded during realizations of the task and target-locked event-related potentials (ERPs) for masked and unmasked conditions were constructed. Time features corresponding to the P100, N150, and P300 components were extracted for each channel separately. Utilizing these features, we employed some common classifiers for classification of the fourfold state. Our task could separate attention and consciousness successfully through their neural correlates. The results indicate that some of the mentioned components changed when attention or consciousness occurs. By comparing difference waves in each condition separately, our results introduce new ERP correlates of attention and consciousness. We also revealed that parieto-occipital areas are the most relevant areas for dissociation between attention and consciousness. To our knowledge, this is the first time that these correlates are introduced in a separable mode, and that the classification accuracies are reported for this purpose.Як вважають, увага та усвідомлення тісно поєднані, проте результати недавніх досліджень дають підстави думати, що один із цих процесів може реалізуватися за відсутності другого. У новітніх експериментах виявилося, що спостерігачі можуть приділяти увагу невидимому (неусвідомлюваному) стимулу і що стимул може чітко розпізнаватися (диференціюватися) за відсутності уваги. Ми запропонували нове психофізіологічне завдання для дослідження нервових корелятів змін рівнів уваги та усвідомлення. Цільові ЕЕГпотенціали, пов’язані з подією (ППП), відводили в умовах пред’явлення замаскованих та незамаскованих візуальних патернів. Часові характеристики компонентів P100, N150 та P300 визначалися роздільно для відведень по кожному ЕЕГканалу. З урахуванням цих характеристик були використані певні загальні класифікатори для параметрів, спостережуваних у всіх чотирьох стимуляційних станах. У нашому тесті ефекти уваги та усвідомлення могли бути успішно розділені відповідно до їх нервових ЕЕГ-корелятів. Згідно з отриманими результатами, згадані вище компоненти ППП змінюються залежно від того, як проявляється увага або усвідомлення. Роздільне порівняння відмінностей між хвилями ППП для кожної з умов дозволило виявити нові кореляти уваги та усвідомлення, що відбиваються в ППП. Показано також, що тім’яно-потиличні кортикальні зони є структурами, найбільшою мірою пов’язаними з дисоціацією ефектів уваги та усвідомлення. Як ми вважаємо, ці кореляти вперше представлені з використанням методики, котра дозволяє їх розрізнити, і наведені дані щодо точності такої диференціації

    Effects of correct and wrong answers on ERPs recorded under conditions of the continuous performance test in ADHD/normal participants

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    Parameters of event-related potentials (ERPs) regarding correct and wrong answers under conditions of the continuous performance test (CPT) were measured in 50 adult subjects with the absence/presence of attention deficit/hyperactivity disorders (ADHD) and characterized by different levels of sustained attention. For ERP extraction, the average for each group of signals, which were time-locked to the onset of stimuli, was calculated; two ERP groups were considered separately for correct and wrong answers. In both groups, the P300 wave was clearly observed. The time dynamics of ERP components were investigated in six defined time blocks. At the peak of P300, a prominent component of brain activity could be observed. Some ERP morphological features (704 items) were extracted from these potentials. The results indicated that 11 of the obtained features had a significant (P<0.01) relation to the level of sustained attention. When comparing correct and wrong answers, 10 features in the normal group and 3 features in the ADHD group demonstrated significant differences (P < 0.05), which means that the participant’s response is reflected in the features of EEG signal. The results reveal a promising relation between CPT results and some parameters of brain signals, which can be used for further evaluations of the sustained attention level.Параметри пов’язаних з подією ЕЕГ-потенціалів (ППП) вимірювали у 50 дорослих тестованих з відсутністю (норма) та наявністю синдрому дефіциту уваги й гіперактивності (АDНD), котрі демонстрували різні градації рівня підтримуваної уваги. Враховували правильність і помилковість відповідей в умовах тесту безперервного виконання (continuous performance test, CPT). Щоб описати ППП, розраховували середні значення для кожної групи сигналів, «прив’язаних» до моменту пред’явлення стимулу. Було виділено дві окремі групи ППП, відповідно до вірних та помилкових відповідей. Хвиля Р300 була чітко представлена в обох групах ППП. Часова динаміка компонентів ППП була досліджена в межах шести ізольованих часових блоків. Пік Р300 віддзеркалював чітко виражений компонент церебральної активності. У складі ППП було виділено низку морфологічних особливостей (усього 704 риси). Виявилося, що 11 з таких рис вірогідно (P < 0.01) корелювали з рівнем постійної уваги. При порівнянні ППП, пов’язаних з вірними та хибними відповідями, істотні відмінності демонстрували 10 рис у групі норми та три риси в групі АDНD (P < 0.05). Це свідчить про те, що характер відповіді тестованого певним чином віддзеркалюється в патерні ЕЕГ-сигналу. Отримані дані вказують на наявність зв’язку між результатами СРТ і деякими параметрами ЕЕГ-сигналів. Це може бути використано для об’єктивної оцінки рівня підтримуваної уваги

    Effects of the adhd syndrome on the frequency composition of ERPs revealed by independent component analysis

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    In this study, we investigated the frequency characteristics of independent components (ICs) of event-related potentials (ERPs) recorded in persons with attention deficit/hyperactivity disorder (ADHD) and normal adults under conditions of continuous performance test (CPT). A group of 50 participants (10 ADHD subjects and 40 ones with no attention disorders) was examined. Independent component analysis was applied to the recorded signals. For ERP extraction, averages for each group of ICs, which were time-locked to the onset of stimuli, were calculated. Several frequency characteristics (704 items) were extracted from different ERPs in each IC. Eight features of the brain signals had a significant (P < 0.001) correlation with the participants’ clinical presentation, which is consistent with the results of previous studies. The revealed promising relation can be used for further evaluation of the sustained attention level.У роботі вивчали частотні характеристики пов’язаних з подією ЕЕГ-потенціалів (ППП) у дорослих тестованих з наявністю синдрому дефіциту уваги й гіперактивності (ADHD) та його відсутністю (норма) в умовах тесту безперервного виконання (continuous performance test, CPT). Дослідження були проведені на 50 добровольцях (10 тестованих з наявністю ADHD і 40 практично здорових людей). Для вивчення ППП використовували методику незалежного компонентного аналізу. Середні величини для кожної групи незалежних компонентів (НК), „прив’язаних” до моменту пред’явлення стимулу, розраховували, щоб описати ППП. У кожному НК у складі різних ППП було виділено низку частотних особливостей (усього 704 риси). Як виявилося, вісім таких рис досліджуваних ППП вірогідно (P < < 0.001) корелювали з клінічними характеристиками тестованих, що узгоджується з результатами, отриманими в попередніх роботах. Наші дані можуть бути використані для об’єктивної оцінки рівня підт римуваної уваги

    Drug-related mutational patterns in hepatitis B virus (HBV) reverse transcriptase proteins from Iranian treatment-Naïve chronic HBV patients

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    Background: Immunomodulators and Nucleotide analogues have been used globally for the dealing of chronic hepatitis B virus (HBV) infection. However, the development of drug resistance is a major limitation to their long-term effectiveness. Objectives: The aim of this study was to characterize the hepatitis B virus reverse transcriptase (RT) protein variations among Iranian chronic HBV carriers who did not receive any antiviral treatments. Materials and Methods: Hepatitis B virus partial RT genes from 325 chronic in active carrier patients were amplified and directly sequenced. Nucleotide/amino acid substitutions were identified compared to the sequences obtained from the database. Results: All strains belonging to genotype D.365 amino-acid substitutions were found. Mutations related to lamivudine, adefovir, telbivudine, and entecavir occurred in (YMDD) 4% (n = 13), (SVQ) 17.23% (n = 56), (M204I/V + L180M) 2.45% (n = 8) and (M204I) 2.76% (n = 9) of patients, respectively. Conclusions: RT mutants do occur naturally and could be found in HBV carriers who have never received antiviral therapy. However, mutations related to drug resistance in Iranian treatment-naïve chronic HBV patients were found to be higher than other studies published formerly. Chronic HBV patients should be monitored closely prior the commencement of therapy to achieve the best regimen option. © 2013, KOWSAR Corp

    Estimation of radiation dose-reduction factor for cerium oxide nanoparticles in MRC-5 human lung fibroblastic cells and MCF-7 breast-cancer cells

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    In the current study, radiation dose-reduction factor (DRF) of nanoceria or cerium oxide nanoparticles (CONPs) in MRC-5 Human Lung Fibroblastic Cells and MCF-7 Breast-Cancer Cells was estimated. Characterization of CONPs was determined using scanner electron microscope (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and spectrophotometer. Then, six plans were designed with different radiation dose values on planning target value. The obtained MRC-5 and MCF-7 cells were treated with non-toxic concentrations of CONPs and then exposed. Finally, cell viability () of the cell lines was determined using MTT assay. The findings showed that CONPs have no significant radioprotective effect against 10 cGy radiation dose value. Nevertheless, 70 μM CONPs resulted in a significant radioprotection against 100, 200, 300, 400 and 500 cGy radiation dose values compared with the control group in MRC-5 cells. For all radiation dose values, mean cell viability () of MCF-7 had not increased significantly at the presence of nanoceria compared with control group. According to the findings, it was revealed that the use of CONPs have a significant radioprotective effect on normal lung cells, while they do not provide any protection for MCF-7 cancer cells. These properties can help to increase therapeutic ratio of radiotherapy. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group

    Modeling the Subsurface Structure of Sunspots

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    While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear inversion techniques do not yet allow helioseismology to probe the internal structure with sufficient confidence to distinguish between the monolith and cluster models, the development of physically realistic sunspot models are a priority for helioseismologists. This is because they are not only important indicators of the variety of physical effects that may influence helioseismic inferences in active regions, but they also enable detailed assessments of the validity of helioseismic interpretations through numerical forward modeling. In this paper, we provide a critical review of the existing sunspot models and an overview of numerical methods employed to model wave propagation through model sunspots. We then carry out an helioseismic analysis of the sunspot in Active Region 9787 and address the serious inconsistencies uncovered by \citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find that this sunspot is most probably associated with a shallow, positive wave-speed perturbation (unlike the traditional two-layer model) and that travel-time measurements are consistent with a horizontal outflow in the surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic

    The effects of slurry on larviculture of Rutilus frisii kutum and chienes carp yield and determination of efficient concentration for increasing of production

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    Rutilus frisii kutum is one of the important fish of Caspian Sea which has significant economical role in the region .The objective of this project is a comparative study on traditional culture of fishes versus slurry. This survey were conducted on nine pound of 1.7 hec triplicate with their treatment with stocking densities of 1.7 million fish larva at Dr yousefpoor center (Affiliated of Shahid Beheshti culture and propagation) at Siakal village , 32 km far from Rasht city in North of Iran, the first treatment considered as control which practice traditionally (using concentrated food plus grinded kilka fish) .In the second treatment for 13 days the pound supplied only by slurry then followed by concentrated fish food only .The tired treatment started with slurry for 13 days and followed by slurry plus concentrated food. The physical and chemical parameters of water, plankton, biometry of fish, growth indices such as daily weight growth (DWG), daily length growth (DLG) as well as specific ratio (SGR) were monitored weekly. The result indicate that net fish production was 1.7 to 2 times higher in slurry than traditional treatment also the survival rate were 1.7 times higher in slurry treatment . The treatment of slurry follow by addition of concentrated food plus slurry showed higher yield camper to others. Slurry with several active substances is more effective and can promote the growth of zooplanktons which is the food of larval stage of rutilus frisi kutum. In second phase of this project the effect of slurry was surveyed on Chinese carp. This experiment was conducted in triplicate with two treatment (one treatment is control which use cow manure plus chemical fertilizer and second treatment was conducted with slurry) and stocked with 2375 N/hec (Silver carp 60%, Big head 15%, common carp 17% and grass carp 8%) at June. In this survey common carp and grass carp were feed with concentrate food and fresh grasses respectively. Chemical factors were measured once for each two week and density of plankton was determined when it was necessarily. Nutritional content of phosphorous, nitrogen, calcium, potassium and magnesium after anaerobic fermentation as well as protein and lipid content with 1.4and 1.9 times respectively were higher in slurry treatment than control. The results showed that survival rate and yield were higher in slurry than control. The increasing percent of yield were 13.5, 2.6, 18.4 and 85.3 in Silver carp, Big head, common carp and grass carp respectively. The survival rate of grass carp was twice higher in slurry treatment than control. Zooplankton abundant in slurry pounds was more but blue- green algae density was less than control. Protein and lipid analysis reviled no significant difference between control and slurry. In general the result indicate that the slurry with higher nutritional content is more effective on the survival and growth rate of fishes and also is more efficient in proliferation of plankton in particular zooplankton

    The feasibility study for culture of Salmo trutta caspius by brackish water

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    Caspian trout is valuable, Commercial, anadromous and endemic fish species in the Caspian Sea so that, researchers attention have been focused on this species. At the moment, only pay attention to stocks rehabilitation that fisheries organization releases more than 300,000 fingerlings to the rivers ends to the Caspian Sea. Importance of this study consist (1) introducing a new species to the aquaculture system and (2) provide breeders in this research. we used from 2 treatments that consist with density of 10 kg/m^3 and 20 kg/m3 with 3 replication. Results showed, culture of Caspian trout is suitable with density 10 kg/m^3, so that weight gain, SGR and Daily growth mean are better than treatment 2(15-20 kg/m^3
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