Universidade Federal de Minas Gerais

About: Universidade Federal de Minas Gerais is a education organization based out in Belo Horizonte, Minas Gerais, Brazil. It is known for research contribution in the topics: Population & Context (language use). The organization has 41631 authors who have published 75688 publications receiving 1249905 citations.

The tube over time: characterizing popularity growth of youtube videos

Abstract: Understanding content popularity growth is of great importance to Internet service providers, content creators and online marketers. In this work, we characterize the growth patterns of video popularity on the currently most popular video sharing application, namely YouTube. Using newly provided data by the application, we analyze how the popularity of individual videos evolves since the video's upload time. Moreover, addressing a key aspect that has been mostly overlooked by previous work, we characterize the types of the referrers that most often attracted users to each video, aiming at shedding some light into the mechanisms (e.g., searching or external linking) that often drive users towards a video, and thus contribute to popularity growth. Our analyses are performed separately for three video datasets, namely, videos that appear in the YouTube top lists, videos removed from the system due to copyright violation, and videos selected according to random queries submitted to YouTube's search engine. Our results show that popularity growth patterns depend on the video dataset. In particular, copyright protected videos tend to get most of their views much earlier in their lifetimes, often exhibiting a popularity growth characterized by a viral epidemic-like propagation process. In contrast, videos in the top lists tend to experience sudden significant bursts of popularity. We also show that not only search but also other YouTube internal mechanisms play important roles to attract users to videos in all three datasets.

Probing the electronic structure of bilayer graphene by Raman scattering

Abstract: The electronic structure of bilayer graphene is investigated from a resonant Raman study of the ${G}^{\ensuremath{'}}$ band using different laser excitation energies. The values of the parameters of the Slonczewski-Weiss-McClure model for bilayer graphene are obtained from the analysis of the dispersive behavior of the Raman features, and reveal the difference of the effective masses of electrons and holes. The splitting of the two TO phonon branches in bilayer graphene is also obtained from the experimental data. Our results have implications for bilayer graphene electronic devices.

The complete genome sequence of Chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability

Abstract: Chromobacterium violaceum is one of millions of species of free-living microorganisms that populate the soil and water in the extant areas of tropical biodiversity around the world. Its complete genome sequence reveals (i) extensive alternative pathways for energy generation, (ii) ≈500 ORFs for transport-related proteins, (iii) complex and extensive systems for stress adaptation and motility, and (iv) widespread utilization of quorum sensing for control of inducible systems, all of which underpin the versatility and adaptability of the organism. The genome also contains extensive but incomplete arrays of ORFs coding for proteins associated with mammalian pathogenicity, possibly involved in the occasional but often fatal cases of human C. violaceum infection. There is, in addition, a series of previously unknown but important enzymes and secondary metabolites including paraquat-inducible proteins, drug and heavy-metal-resistance proteins, multiple chitinases, and proteins for the detoxification of xenobiotics that may have biotechnological applications.

Activation of TLR2 and TLR4 by Glycosylphosphatidylinositols Derived from Toxoplasma gondii

Abstract: GPIs isolated from Toxoplasma gondii , as well as a chemically synthesized GPI lacking the lipid moiety, activated a reporter gene in Chinese hamster ovary cells expressing TLR4, while the core glycan and lipid moieties cleaved from the GPIs activated both TLR4- and TLR2-expressing cells. MyD88, but not TLR2, TLR4, or CD14, is absolutely needed to trigger TNF-α production by macrophages exposed to T. gondii GPIs. Importantly, TNF-α response to GPIs was completely abrogated in macrophages from TLR2/4-double-deficient mice. MyD88 −/− mice were more susceptible to death than wild-type (WT), TLR2 −/− , TLR4 −/− , TLR2/4 −/− , and CD14 −/− mice infected with the ME-49 strain of T. gondii . The cyst number was higher in the brain of TLR2/4 −/− , but not TLR2 −/− , TLR4 −/− , and CD14 −/− , mice, as compared with WT mice. Upon infection with the ME-49 strain of T. gondii , we observed no decrease of IL-12 and IFN-γ production in TLR2-, TLR4-, or CD14-deficient mice. Indeed, splenocytes from T. gondii -infected TLR2 −/− and TLR2/4 −/− mice produced more IFN-γ than cells from WT mice in response to in vitro stimulation with parasite extracts enriched in GPI-linked surface proteins. Together, our results suggest that both TLR2 and TLR4 receptors may participate in the host defense against T. gondii infection through their activation by the GPIs and could work together with other MyD88-dependent receptors, like other TLRs or even IL-18R or IL-1R, to obtain an effective host response against T. gondii infection.