18,062 research outputs found

    Intensified Arctic warming under greenhouse warming by vegetation–atmosphere–sea ice interaction

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    Observations and modeling studies indicate that enhanced vegetation activities over high latitudes under an elevated CO2 concentration accelerate surface warming by reducing the surface albedo. In this study, we suggest that vegetation-atmosphere-sea ice interactions over high latitudes can induce an additional amplification of Arctic warming. Our hypothesis is tested by a series of coupled vegetation-climate model simulations under 2xCO(2) environments. The increased vegetation activities over high latitudes under a 2xCO(2) condition induce additional surface warming and turbulent heat fluxes to the atmosphere, which are transported to the Arctic through the atmosphere. This causes additional sea-ice melting and upper-ocean warming during the warm season. As a consequence, the Arctic and high-latitude warming is greatly amplified in the following winter and spring, which further promotes vegetation activities the following year. We conclude that the vegetation-atmosphere-sea ice interaction gives rise to additional positive feedback of the Arctic amplification.open1188sciescopu

    Titania Nanomaterials Produced from Ti-Salt Flocculated Sludge in Water Treatment

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    Titania is the most widely used metal oxide for the applications of pigments, paper, solar cells and environmental purification. In order to meet the demand of a large amount of titania, our group has developed a novel process which could significantly lower the cost of waste disposal in water treatment, protect the environment and public health and yield economically valuable titania. Titanium tetrachloride (TiCl4) or titanium sulfate (Ti(SO4)2) as an alternative coagulant in water treatment has been explored for the removal of various pollutants from contaminated water or wastewater. Flocculation efficiencies of the Ti-salts were superior to those of Al- and Fe- salts with additional benefits in that a large amount of titania can be produced by calcinating the flocculated floc. The produced titania showed high photocatalytic activity for the removal of volatile organic compounds. The large amount of titania can be applied to pigments, environment and construction materials which require a lot of titania usages. This review paper presents an historical progress from fundamental to application in terms of the detailed production process, characterization, photoactivity of titania produced from Ti-salt flocculated sludge, and its various applications. © 2011 Springer Science+Business Media, LLC

    Effect of cholecalciferol on unsaturated model membranes

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    Vitamin D plays an important role in many physiological processes, particularly calcium and phosphorous homeostasis. The biochemistry of vitamin D is also complex, encompassing a range of active molecules that may be either endogenous or dietary in origin. The role of lipids and fats in the production, processing and use of vitamin D is an interesting one, with a relative paucity of model studies into the interactions of vitamin D with lipidic systems such as micelles and vesicles. Here, we have studied the effect of vitamin D3 in simple unsaturated phospholipid systems. We used NMR and FTIR spectroscopy to investigate the effect of increasing vitamin D concentration on the structure and dynamics of the lipid chains and interfacial region. In order to link these model studies with more complex biomimetic environments, we compare results in the presence of buffer and vitamin D binding protein. We have also used DLS to determine that vitamin D3-DOPC vesicles can retain their size distribution for varying amounts of time in different conditions. We find that the acyl chain region of vitamin D3-DOPC membranes are generally disordered, and that the addition of buffer and/or protein alters the properties of the interfacial region

    Visible light responsive titanium dioxide (TiO<inf>2</inf>)

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    Titanium dioxide (TiO2) is one of the most researched semiconductor oxides that has revolutionised technologies in the field of environmental purification and energy generation. It has found extensive applications in heterogenous photocatalysis for removing organic pollutants from air and water and also in hydrogen production from photocatalytic water-splitting. Its use is popular because of its low cost, low toxicity, high chemical and thermal stability, But one of the critical limitations of TiO 2 as photocatalyst is its poor response to visible light. Several attempts have been made to modify the surface and electronic structures of TiO2 to enhance its activity in the visible light region such as noble metal deposition, metal ion loading, cationic and anionic doping and sensitisation, Most of the results improved photocatalytic performance under visible light irradiation. This paper attempts to review and update some of the information on the TiO2 photocatalytic technology and its accomplishment towards visible light region

    Preparation and characterisation of titanium dioxide produced from Ti-salt flocculated sludge in water treatment

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    During the past few years, titanium salts were investigated as alternative coagulants for the removal of organic matter of different molecular sizes in contaminated water. The flocculation efficiency of Ti-salt was comparable to those of FeCl3 and Al2(SO4)3 salts, commonly used coagulants. Incinerated sludge-TiO2 showed higher surface area and photocatalytic activity than commercially available TiO2. Metal-doped forms were produced by adding coagulant aids such as iron (Fe-), aluminium (Al-) and (Ca-) calcium salts during Ti-salt flocculation to increase pH. Ca- and Al- doped TiO2 showed very high photocatalytic activity compared to Fe-doped TiO2. When tested in a pilot scale plant for treatment of dye wastewater to check practical feasibility of the novel process, the removal ratio of the chemical oxygen demand was comparable to those of commonly used coagulants but the settling of sludge was faster. The TiO2 generated after sludge incineration showed a high photocatalytic activity for degradation of volatile organic compounds and increased the rate of hydrogen production by water photosplitting. TiCl4 coagulant and TiO2 produced from different water sources with different concentrations had low acute toxicity compared to heavy metals and commercial TiO2 when examined based on D. Magna mortality. This paper presents the production, characterisation and the photoactivity of TiO2 produced from Ti-salt flocculated sludge. Different case studies are discussed to highlighted recent advances in this field

    Matrix Models for Supersymmetric Chern-Simons Theories with an ADE Classification

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    We consider N=3 supersymmetric Chern-Simons (CS) theories that contain product U(N) gauge groups and bifundamental matter fields. Using the matrix model of Kapustin, Willett and Yaakov, we examine the Euclidean partition function of these theories on an S^3 in the large N limit. We show that the only such CS theories for which the long range forces between the eigenvalues cancel have quivers which are in one-to-one correspondence with the simply laced affine Dynkin diagrams. As the A_n series was studied in detail before, in this paper we compute the partition function for the D_4 quiver. The D_4 example gives further evidence for a conjecture that the saddle point eigenvalue distribution is determined by the distribution of gauge invariant chiral operators. We also see that the partition function is invariant under a generalized Seiberg duality for CS theories.Comment: 20 pages, 3 figures; v2 refs added; v3 conventions in figure 3 altered, version to appear in JHE

    Clinical significance of amyloid β positivity in patients with probable cerebral amyloid angiopathy markers

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    Purpose: We investigated the frequency and clinical significance of amyloid β (Aβ) positivity on PET in patients with cerebral amyloid angiopathy (CAA). / Methods: We recruited 65 patients who met the modified Boston criteria for probable CAA. All underwent amyloid PET, MRI, APOE genotyping and neuropsychological testing, and we obtained information on MRI markers of CAA and ischemic cerebral small-vessel disease (CSVD). We investigated the CAA/ischemic CSVD burden and APOE genotypes in relation to Aβ positivity and investigated the effect of Aβ positivity on longitudinal cognitive decline. / Results: Among the 65 CAA patients, 43 (66.2%) showed Aβ PET positivity (Aβ+). Patients with Aβ+ CAA had more lobar microbleeds (median 9, interquartile range 2–41, vs. 3, 2–8; P = 0.045) and a higher frequency of cortical superficial siderosis (34.9% vs. 9.1%; P = 0.025), while patients with Aβ− CAA had more lacunes (1, 0–2, vs. 0, 0–1; P = 0.029) and a higher frequency of severe white matter hyperintensities (45.5% vs. 20.9%; P = 0.040). The frequency of ε4 carriers was higher in Aβ+ patients (57.1%) than in Aβ− patients (18.2%; P = 0.003), while the frequency of ε2 carriers did not differ between the two groups. Finally, Aβ positivity was associated with faster decline in multiple cognitive domains including language (P < 0.001), visuospatial function (P < 0.001), and verbal memory (P < 0.001) in linear mixed effects models. / Conclusion: Our findings suggest that a significant proportion of patients with probable CAA in a memory clinic are Aβ− on PET. Aβ positivity in CAA patients is associated with a distinct pattern of CSVD biomarker expression, and a worse cognitive trajectory. Aβ positivity has clinical relevance in CAA and might represent either advanced CAA or additional Alzheimer’s disease neuropathological changes

    Prevalence and predictors of video game addiction: a study based on a national representative sample of gamers

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    Video gaming has become a popular leisure activity in many parts of the world, and an increasing number of empirical studies examine the small minority that appears to develop problems as a result of excessive gaming. This study investigated prevalence rates and predictors of video game addiction in a sample of gamers, randomly selected from the National Population Registry of Norway (N =3389). Results showed there were 1.4 % addicted gamers, 7.3 % problem gamers, 3.9 % engaged gamers, and 87.4 % normal gamers. Gender (being male) and age group (being young) were positively associated with addicted-, problem-, and engaged gamers. Place of birth (Africa, Asia, South- and Middle America) were positively associated with addicted- and problem gamers. Video game addiction was negatively associated with conscientiousness and positively associated with neuroticism. Poor psychosomatic health was positively associated with problem- and engaged gaming. These factors provide insight into the field of video game addiction, and may help to provide guidance as to how individuals that are at risk of becoming addicted gamers can be identified

    Operator Counting for N=2 Chern-Simons Gauge Theories with Chiral-like Matter Fields

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    The localization formula of Chern-Simons quiver gauge theory on S3S^3 nicely reproduces the geometric data such as volume of Sasaki-Einstein manifolds in the large-NN limit, at least for vector-like models. The validity of chiral-like models is not established yet, due to technical problems in both analytic and numerical approaches. Recently Gulotta, Herzog and Pufu suggested that the counting of chiral operators can be used to find the eigenvalue distribution of quiver matrix models. In this paper we apply this method to some vector-like or chiral-like quiver theories, including the triangular quivers with generic Chern-Simons levels which are dual to in-homogeneous Sasaki-Einstein manifolds Yp,k(CP2)Y^{p,k}(\mathbb{CP}^2). The result is consistent with AdS/CFT and the volume formula. We discuss the implication of our analysis.Comment: 23 pages; v2. revised version; v3. corrected typos and clarified argument

    CHẤT LƯỢNG LỄ HỘI CẦU NGƯ Ở THUẬN AN, PHÚ VANG, THỪA THIÊN HUẾ

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    Lễ hội Cầu Ngư ở Thuận An, Phú Vang, Thừa Thiên Huế được tổ chức từ ngày 10 đến 12 tháng giêng âm lịch hàng năm. Lễ hội này đã và đang là hoạt động thu hút ngày càng nhiều du khách khi đến Huế. Việc đánh giá chất lượng lễ hội Cầu Ngư Thuận An, tìm ra những thành công và hạn chế, từ đó đề xuất giải pháp góp phần nâng cao chất lượng của lễ hội có ý nghĩa quan trọng trong việc thu hút khách du lịch trong và ngoài nước. Phương pháp phân tích nhân tố được sử dụng để đánh giá chất lượng lễ hội này, trong đó mô hình phân tích được đo bằng 5 nhân tố: nguồn thông tin về lễ hội, đặc trưng chung của lễ hội, cơ sở hạ tầng và trang thiết bị phục vụ hoạt động lễ hội, hoạt động lễ hội, và thoả mãn mục đích đến với lễ hội. Năm nhân tố đó được đo bằng 28 biến quan sát trên cơ sở điều tra khảo sát 147 du khách đến với lễ hội. Kết quả nghiên cứu cho thấy hai nhân tố  là nguồn thông tin về lễ hội và cơ sở hạ tầng, và trang thiết bị phục vụ lễ hội có điểm trung bình tương ứng là 3,24 và 3,45, thấp hơn so với các nhân tố khác. Nhân tố đặc trưng lễ hội có điểm đánh giá là 3,78. Hai nhân tố gồm thoả mãn mục đích đến với lễ hội và hoạt động tổ chức lễ hội có điểm đánh giá rất cao tương ứng là 4,19 và 4,23. Kết quả nghiên cứu cũng cho thấy 54,8 % số du khách có ý định quay lại lễ hội và 45 % số du khách có ý định giới thiệu với bạn bè và người thân về lễ hội này. Để góp phần nâng cao chất lượng lễ hội, hai nhóm giải pháp gồm quảng bá, tuyên truyền và tăng cường cơ sở vật chất, trang thiết bị kỹ thuật cho hoạt động lễ hội cần được đặc biệt quan tâm.Từ khoá: lễ hội, Cầu Ngư, chất lượn
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