611 research outputs found

    Seasonal and regional distribution of phytoplankton in the southern Caspian Sea

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    Seasonal distribution of species composition, cell abundance and biomass of phytoplankton of the Caspian Sea were investigated in 2005. This survey were fulfilled in 6 transects and 26 stations A total of 260 samples were collected during winter to autumn in the southern part of Caspian Sea. Totally, 163 species of phytoplankton were identified (71 species Bacillariophyta, 31 species Chlorophyta, 27 species Cyanophyta, 21 species Pyrrophyta, and 13 species Euglenophyta). Cell abundance and biomass of Bacillariophyta were high in centre, while biomass and cell abundance of Pyrrophyta were dominant in the middle as well as parts of the Sea, respectively. The overall total average of cell abundance and biomass of phytoplankton were 56.30± 30.97 ×106cells/m3 and 221.70±75.87 mg/m3, respectively. Bacillariophyta accounted for 47% in cell abundance, and Pyrrophyta consisted of 53% of the phytoplankton biomass. Maximum phytoplankton population was recorded in winter due to Bacillariophyta and the maximum biomass in spring due to Pyrrophyta. The maximum density of Bacillariophyta was in winter and autumn while maximum biomass was observed in spring due to bigger size of Bacillariophyta such as Rhizosolenia calcar avis and Nitzschia sigmoidea followed by Pyrrophyta with high cell abundance throughout the year

    A Cosine Similarity-Based Method to Infer Variability of Chromatin Accessibility at the Single-Cell Level

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    Cellular identity between generations of developing cells is propagated through the epigenome particularly via the accessible parts of the chromatin. It is now possible to measure chromatin accessibility at single-cell resolution using single-cell assay for transposase accessible chromatin (scATAC-seq), which can reveal the regulatory variation behind the phenotypic variation. However, single-cell chromatin accessibility data are sparse, binary, and high dimensional, leading to unique computational challenges. To overcome these difficulties, we developed PRISM, a computational workflow that quantifies cell-to-cell chromatin accessibility variation while controlling for technical biases. PRISM is a novel multidimensional scaling-based method using angular cosine distance metrics coupled with distance from the spatial centroid. PRISM takes differences in accessibility at each genomic region between single cells into account. Using data generated in our lab and publicly available, we showed that PRISM outperforms an existing algorithm, which relies on the aggregate of signal across a set of genomic regions. PRISM showed robustness to noise in cells with low coverage for measuring chromatin accessibility. Our approach revealed the previously undetected accessibility variation where accessible sites differ between cells but the total number of accessible sites is constant. We also showed that PRISM, but not an existing algorithm, can find suppressed heterogeneity of accessibility at CTCF binding sites. Our updated approach uncovers new biological results with profound implications on the cellular heterogeneity of chromatin architecture

    New combined PIC-MCC approach for fast simulation of a radio frequency discharge at low gas pressure

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    A new combined PIC-MCC approach is developed for accurate and fast simulation of a radio frequency discharge at low gas pressure and high density of plasma. Test calculations of transition between different modes of electron heating in a ccrf discharge in helium and argon show a good agreement with experimental data. We demonstrate high efficiency of the combined PIC-MCC algorithm, especially for the collisionless regime of electron heating.Comment: 6 paged, 8 figure

    Generalized Uncertainty Principle and the Ramsauer-Townsend Effect

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    The scattering cross section of electrons in noble gas atoms exhibits a minimum value at electron energies of approximately 1eV. This is the Ramsauer-Townsend effect. In this letter, we study the Ramsauer-Townsend effect in the framework of the Generalized Uncertainty Principle.Comment: 11 pages, 3 figure

    EXPERIMENTAL STUDY OF HEAVY CONCRETE BEHAVIOR UNDER FREE-AIR BLAST AND SURFACE

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    ABSTRACT In designing defensive structures, often dynamic loadings such as blast and impact is taken into account. With the progress of technologies of ballistic shield, preparing materials with the ability to withstand dynamic loads is considered by many scholars. For this ability, the concrete has a vast usage as an effective material. The present research, toward this end, will exhibit experimental and analytical processes of heavy concrete (high density) blast resistance and improving its behavior against the explosion, compared to conventional concretes. The research is conducted through 3 stages: 1-Final mixing plans are, presented and after sampling, testing physical and mechanical properties, according to BS and ASTM standards, of cubic specimens with a size of 15 cm by15 cm and cylindrical specimens with a size of 15 cm by 30 cm is done and results are given 2-in order to study the explosive resistance, specimens sizing 50×50×10cm were prepared and after preparing the conditions of field test using TNT explosive, placing the explosive at 0, 10 and 20 cm distances, an explosion was performed on the pieces. 3-conclusion: after experimental studies, it was found that special heavy concrete for this research has better performance compared with conventional concrete

    Decompressive hemicraniectomy in severe cerebral venous thrombosis: a prospective case series

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    Small retrospective case series suggest that decompressive hemicraniectomy can be life saving in patients with cerebral venous thrombosis (CVT) and impending brain herniation. Prospective studies of consecutive cases are lacking. Thus, a single centre, prospective study was performed. In 2006 we adapted our protocol for CVT treatment to perform acute decompressive hemicraniectomy in patients with impending herniation, in whom the prognosis with conservative treatment was considered infaust. We included all consecutive patients with CVT between 2006 and 2010 who underwent hemicraniectomy. Outcome was assessed at 12 months with the modified Rankin Scale (mRS). Ten patients (8 women) with a median age of 41 years (range 26–52 years) were included. Before surgery 5 patients had GCS < 9, 9 patients had normal pupils, 1 patient had a unilaterally fixed and dilated pupil. All patients except one had space-occupying intracranial hemorrhagic infarcts. The median preoperative midline shift was 9 mm (range 3–14 mm). Unilateral hemicraniectomy was performed in 9 patients and bilateral hemicraniectomy in one. Two patients died from progressive cerebral edema and expansion of the hemorrhagic infarcts. Five patients recovered without disability at 12 months (mRS 0–1). Two patients had some residual handicap (one minor, mRS 2; one moderate, mRS 3). One patient was severely handicapped (mRS 5). Our prospective data show that decompressive hemicraniectomy in the most severe cases of cerebral venous thrombosis was probably life saving in 8/10 patients, with a good clinical outcome in six. In 2 patients death was caused by enlarging hemorrhagic infarcts

    Acetazolamide for the prophylaxis of migraine in CADASIL: a preliminary experience

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    Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited microangiopathy caused by NOTCH3 mutations. It is characterized by migraine, with or without aura, ischemic events, psychiatric and cognitive disturbances. There is no approved treatment for migraine prophylaxis in CADASIL, but acetazolamide has been anecdotally reported to be effective. We retrospectively reviewed our database of patients with a genetic diagnosis of CADASIL to identify how many of them were treated with acetazolamide for the prophylaxis of migraine. The efficacy and the tolerability of this treatment were checked looking at the clinic reports. Acetazolamide was prescribed in seven patients; the mean duration of treatment was 6 months, and the daily dose ranged from 125 to 500 mg. Three patients had a total and sustained remission, while in two patients a reduction in attacks and an improvement of the headache intensity were recorded. In one of these, acetazolamide was deliberately taken only during the migraine attack and the beneficial effect started 1 h after administration. In two patients, the drug did not produce any beneficial effect. Mild side effects were recorded in two patients. Our preliminary experience expands previous reports and confirms the possible efficacy of acetazolamide in CADASIL migraine. Based on these data, a randomized controlled trial seems worthy to be carried out to test the efficacy and safety of this drug
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