707 research outputs found

    Wide-range head pose estimation for low resolution video

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    Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, February 2008.Includes bibliographical references (p. 85-87).This thesis focuses on data mining technologies to extract head pose information from low resolution video recordings. Head pose, as an approximation of gaze direction, is a key indicator of human behavior and interaction. Extracting head pose information from video recordings is a labor intensive endeavor that severely limits the feasibility of using large video corpora to perform tasks that require analysis of human behavior. HeadLock is a novel head pose annotation and tracking tool. Pose annotation is formulated as a semiautomatic process in which a human annotator is aided by computationally generated head pose estimates, significantly reducing the human effort required to accurately annotate video recordings. HeadLock has been designed to perform head pose tracking on video from overhead, wide-angle cameras. The head pose estimation system used by HeadLock can perform pose estimation to arbitrary precision on images that reveal only the top or back of a head. This system takes a 3D model-based approach in which heads are modeled as 3D surfaces covered with localized features. The set of features used can be reliably extracted from both hair and skin regions at any resolution, providing better performance for images that may contain small facial regions and no discernible facial features. HeadLock is evaluated on video recorded for the Human Speechome Project (HSP), a research initiative to study human language development by analyzing longitudinal audio-video recordings of a developing child. Results indicate that HeadLock may enable annotation of head pose at ten times the speed of a manual approach. In addition to head tracking, this thesis describes the data collection and data management systems that have been developed for HSP, providing a comprehensive example of how very large corpora of video recordings may be used to research human development, health and behavior.by Philip DeCamp.S.M

    Data visualization in the first person

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, February 2013.Cataloged from PDF version of thesis. "February 2013."Includes bibliographical references (p. 103-107).This dissertation will examine what a first person viewpoint means in the context of data visualization and how it can be used for navigating and presenting large datasets. Recent years have seen rapid growth in Big Data methodologies throughout scientific research, business analytics, and online services. The datasets used in these areas are not only growing exponentially larger, but also more complex, incorporating heterogeneous data from many sources that might include digital sensors, websites, mass media, and others. The scale and complexity of these datasets pose significant challenges in the design of effective tools for navigation and analysis. This work will explore methods of representing large datasets as physical, navigable environments. Much of the related research on first person interfaces and 3D visualization has focused on producing tools for expert users and scientific analysis. Due to the complexities of navigation and perception introduced by 3D interfaces, work in this area has had mixed results. In particular, considerable efforts to develop 3D systems for more abstract data, like file systems and social networks, have had difficulty surpassing the efficiency of 2D approaches. However, 3D may offer advantages that have been less explored in this context. In particular, data visualization can be a valuable tool for disseminating scientific results, sharing insights, and explaining methodology. In these applications, clear communication of concepts and narratives are often more essential than efficient navigation. This dissertation will present novel visualization systems designed for large datasets that include audio-video recordings, social media, and others. Discussion will focus on designing visuals that use the first person perspective to give a physical and intuitive form to abstract data, to combine multiple sources of data within a shared space, to construct narratives, and to engage the viewer at a more visceral and emotional level.by Philip DeCamp.Ph.D

    An immersive system for browsing and visualizing surveillance video

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    HouseFly is an interactive data browsing and visualization system that synthesizes audio-visual recordings from multiple sensors, as well as the meta-data derived from those recordings, into a unified viewing experience. The system is being applied to study human behavior in both domestic and retail situations grounded in longitudinal video recordings. HouseFly uses an immersive video technique to display multiple streams of high resolution video using a realtime warping procedure that projects the video onto a 3D model of the recorded space. The system interface provides the user with simultaneous control over both playback rate and vantage point, enabling the user to navigate the data spatially and temporally. Beyond applications in video browsing, this system serves as an intuitive platform for visualizing patterns over time in a variety of multi-modal data, including person tracks and speech transcripts.United States. Office of Naval Research (Award no. N000140910187

    Two randomized trials of neutralizing antibodies to prevent HIV-1 acquisition

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    BACKGROUND : Whether a broadly neutralizing antibody (bnAb) can be used to prevent human immunodeficiency virus type 1 (HIV-1) acquisition is unclear. METHODS : We enrolled at-risk cisgender men and transgender persons in the Americas and Europe in the HVTN 704/HPTN 085 trial and at-risk women in sub-Saharan Africa in the HVTN 703/HPTN 081 trial. Participants were randomly assigned to receive, every 8 weeks, infusions of a bnAb (VRC01) at a dose of either 10 or 30 mg per kilogram (low-dose group and high-dose group, respectively) or placebo, for 10 infusions in total. HIV-1 testing was performed every 4 weeks. The VRC01 80% inhibitory concentration (IC80) of acquired isolates was measured with the TZM-bl assay. RESULTS : Adverse events were similar in number and severity among the treatment groups within each trial. Among the 2699 participants in HVTN 704/HPTN 085, HIV-1 infection occurred in 32 in the low-dose group, 28 in the high-dose group, and 38 in the placebo group. Among the 1924 participants in HVTN 703/HPTN 081, infection occurred in 28 in the low-dose group, 19 in the high-dose group, and 29 in the placebo group. The incidence of HIV-1 infection per 100 person-years in HVTN 704/ HPTN 085 was 2.35 in the pooled VRC01 groups and 2.98 in the placebo group (estimated prevention efficacy, 26.6%; 95% confidence interval [CI], −11.7 to 51.8; P = 0.15), and the incidence per 100 person-years in HVTN 703/HPTN 081 was 2.49 in the pooled VRC01 groups and 3.10 in the placebo group (estimated prevention efficacy, 8.8%; 95% CI, −45.1 to 42.6; P = 0.70). In prespecified analyses pooling data across the trials, the incidence of infection with VRC01-sensitive isolates (IC80 <1 μg per milliliter) per 100 person-years was 0.20 among VRC01 recipients and 0.86 among placebo recipients (estimated prevention efficacy, 75.4%; 95% CI, 45.5 to 88.9). The prevention efficacy against sensitive isolates was similar for each VRC01 dose and trial; VRC01 did not prevent acquisition of other HIV-1 isolates. CONCLUSIONS : VRC01 did not prevent overall HIV-1 acquisition more effectively than placebo, but analyses of VRC01-sensitive HIV-1 isolates provided proof-of-concept that bnAb prophylaxis can be effective.Supported by Public Health Service Grants (UM1 AI068614, to the HIV Vaccine Trials Network [HVTN]; UM1 AI068635, to the HVTN Statistical Data and Management Center [SDMC], Fred Hutchinson Cancer Research Center [FHCRC]; UM1 AI068618, to HVTN Laboratory Center, FHCRC; UM1 AI068619, to the HPTN Leadership and Operations Center; UM1 AI068613, to the HIV Prevention Trials Network [HPTN] Laboratory Center; UM1 AI068617, to the HPTN SDMC; and P30 AI027757, to the Center for AIDS Research, University of Washington) from the National Institute of Allergy and Infectious Diseases (NIAID) and by the Intramural Research Program of the NIAID.http://www.nejm.orgam2022School of Health Systems and Public Health (SHSPH

    Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

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    The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of ttt\overline{t}, W+bbW+b\overline{b} and W+ccW+c\overline{c} is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 ±\pm 0.02 \mbox{fb}^{-1}. The WW bosons are reconstructed in the decays WνW\rightarrow\ell\nu, where \ell denotes muon or electron, while the bb and cc quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions

    Measurement of the (eta c)(1S) production cross-section in proton-proton collisions via the decay (eta c)(1S) -&gt; p(p)over-bar

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    Search for the lepton flavour violating decay tau(-) -&gt; mu(-)mu(+)mu(-)

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    A search for the lepton flavour violating decay τμμ+μ\tau^-\rightarrow\mu^-\mu^+\mu^- is performed with the LHCb experiment. The data sample corresponds to an integrated luminosity of 1.0 fb1^{−1} of proton-proton collisions at a centre-of-mass energy of 7 TeV and 2.0 fb1^{−1} at 8 TeV. No evidence is found for a signal, and a limit is set at 90% confidence level on the branching fraction, B(τμμ+μ)<4.6×108\mathcal{B}(\tau^-\rightarrow\mu^-\mu^+\mu^-)<4.6\times10^{−8}.A search for the lepton flavour violating decay τ^{−} → μ^{−} μ+^{+} μ^{−} is performed with the LHCb experiment. The data sample corresponds to an integrated luminosity of 1.0 fb1^{−1} of proton-proton collisions at a centre-of-mass energy of 7 TeV and 2.0 fb1^{−1} at 8 TeV. No evidence is found for a signal, and a limit is set at 90% confidence level on the branching fraction, B(τμμ+μ)<4.6×108 \mathrm{\mathcal{B}}\left({\tau}^{-}\to {\mu}^{-}{\mu}^{+}{\mu}^{-}\right)<4.6\times {10}^{-8} .A search for the lepton flavour violating decay τμμ+μ\tau^-\to \mu^-\mu^+\mu^- is performed with the LHCb experiment. The data sample corresponds to an integrated luminosity of 1.0fb11.0\mathrm{\,fb}^{-1} of proton-proton collisions at a centre-of-mass energy of 7TeV7\mathrm{\,Te\kern -0.1em V} and 2.0fb12.0\mathrm{\,fb}^{-1} at 8TeV8\mathrm{\,Te\kern -0.1em V}. No evidence is found for a signal, and a limit is set at 90%90\% confidence level on the branching fraction, B(τμμ+μ)<4.6×108\mathcal{B}(\tau^-\to \mu^-\mu^+\mu^-) < 4.6 \times 10^{-8}

    Search for CP violation using T-odd correlations in D-0 -&gt; K+K-pi(+)pi(-) decays

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    A search for CPCP violation using TT-odd correlations is performed using the four-body D0K+Kπ+πD^0 \to K^+K^-\pi^+\pi^- decay, selected from semileptonic BB decays. The data sample corresponds to integrated luminosities of 1.0fb11.0\,\text{fb}^{-1} and 2.0fb12.0\,\text{fb}^{-1} recorded at the centre-of-mass energies of 7 TeV and 8 TeV, respectively. The CPCP-violating asymmetry aCPT-odda_{CP}^{T\text{-odd}} is measured to be (0.18±0.29(stat)±0.04(syst))%(0.18\pm 0.29\text{(stat)}\pm 0.04\text{(syst)})\%. Searches for CPCP violation in different regions of phase space of the four-body decay, and as a function of the D0D^0 decay time, are also presented. No significant deviation from the CPCP conservation hypothesis is found

    Measurements of prompt charm production cross-sections in pp collisions at s=5 \sqrt{s}=5 TeV

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    Production cross-sections of prompt charm mesons are measured using data from pppp collisions at the LHC at a centre-of-mass energy of 55\,TeV. The data sample corresponds to an integrated luminosity of 8.60±0.338.60\pm0.33\,pb1^{-1} collected by the LHCb experiment. The production cross-sections of D0D^0, D+D^+, Ds+D_s^+, and D+D^{*+} mesons are measured in bins of charm meson transverse momentum, pTp_{\text{T}}, and rapidity, yy. They cover the rapidity range 2.0<y<4.52.0 < y < 4.5 and transverse momentum ranges 0<pT<10GeV/c0 < p_{\text{T}} < 10\, \text{GeV}/c for D0D^0 and D+D^+ and 1<pT<10GeV/c1 < p_{\text{T}} < 10\, \text{GeV}/c for Ds+D_s^+ and D+D^{*+} mesons. The inclusive cross-sections for the four mesons, including charge-conjugate states, within the range of 1<pT<8GeV/c1 < p_{\text{T}} < 8\, \text{GeV}/c are determined to be \begin{equation*} \sigma(pp\rightarrow D^0 X) = 1190 \pm 3 \pm 64\,\mu\text{b} \end{equation*} \begin{equation*} \sigma(pp\rightarrow D^+ X) = 456 \pm 3 \pm 34\,\mu\text{b} \end{equation*} \begin{equation*} \sigma(pp\rightarrow D_s^+ X) = 195 \pm 4 \pm 19\,\mu\text{b} \end{equation*} \begin{equation*} \sigma(pp\rightarrow D^{*+} X)= 467 \pm 6 \pm 40\,\mu\text{b} \end{equation*} where the uncertainties are statistical and systematic, respectively.Production cross-sections of prompt charm mesons are measured using data from pp collisions at the LHC at a centre-of-mass energy of 5 TeV. The data sample corresponds to an integrated luminosity of 8.60 ± 0.33 pb1^{−1} collected by the LHCb experiment. The production cross-sections of D0^{0}, D+^{+}, Ds+_{s}^{+} , and D+^{∗+} mesons are measured in bins of charm meson transverse momentum, pT_{T}, and rapidity, y. They cover the rapidity range 2.0 < y < 4.5 and transverse momentum ranges 0 < pT_{T} < 10 GeV/c for D0^{0} and D+^{+} and 1 < pT_{T} < 10 GeV/c for Ds+_{s}^{+} and D+^{∗+} mesons. The inclusive cross-sections for the four mesons, including charge-conjugate states, within the range of 1 < pT_{T} < 8 GeV/c are determined to be σ(ppD0X)=1004±3±54μb,σ(ppD+X)=402±2±30μb,σ(ppDs+X)=170±4±16μb,σ(ppD+X)=421±5±36μb, \begin{array}{l}\sigma \left( pp\to {D}^0X\right)=1004\pm 3\pm 54\mu \mathrm{b},\\ {}\sigma \left( pp\to {D}^{+}X\right)=402\pm 2\pm 30\mu \mathrm{b},\\ {}\sigma \left( pp\to {D}_s^{+}X\right)=170\pm 4\pm 16\mu \mathrm{b},\\ {}\sigma \left( pp\to {D}^{\ast +}X\right)=421\pm 5\pm 36\mu \mathrm{b},\end{array} where the uncertainties are statistical and systematic, respectively.Production cross-sections of prompt charm mesons are measured using data from pppp collisions at the LHC at a centre-of-mass energy of 55\,TeV. The data sample corresponds to an integrated luminosity of 8.60±0.338.60\pm0.33\,pb1^{-1} collected by the LHCb experiment. The production cross-sections of D0D^0, D+D^+, Ds+D_s^+, and D+D^{*+} mesons are measured in bins of charm meson transverse momentum, pTp_{\text{T}}, and rapidity, yy. They cover the rapidity range 2.0<y<4.52.0<y<4.5 and transverse momentum ranges 0<pT<10GeV/c0 < p_{\text{T}} < 10\, \text{GeV}/c for D0D^0 and D+D^+ and 1<pT<10GeV/c1 < p_{\text{T}} < 10\, \text{GeV}/c for Ds+D_s^+ and D+D^{*+} mesons. The inclusive cross-sections for the four mesons, including charge-conjugate states, within the range of 1<pT<8GeV/c1 < p_{\text{T}} < 8\, \text{GeV}/c are determined to be \sigma(pp\rightarrow D^0 X) = 1004 \pm 3 \pm 54\,\mu\text{b} \sigma(pp\rightarrow D^+ X) = 402 \pm 2 \pm 30\,\mu\text{b} \sigma(pp\rightarrow D_s^+ X) = 170 \pm 4 \pm 16\,\mu\text{b} \sigma(pp\rightarrow D^{*+} X)= 421 \pm 5 \pm 36\,\mu\text{b} where the uncertainties are statistical and systematic, respectively

    Observation of the B0 → ρ0ρ0 decay from an amplitude analysis of B0 → (π+π−)(π+π−) decays

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    Proton–proton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb−1 , are analysed to search for the charmless B0→ρ0ρ0 decay. More than 600 B0→(π+π−)(π+π−) signal decays are selected and used to perform an amplitude analysis, under the assumption of no CP violation in the decay, from which the B0→ρ0ρ0 decay is observed for the first time with 7.1 standard deviations significance. The fraction of B0→ρ0ρ0 decays yielding a longitudinally polarised final state is measured to be fL=0.745−0.058+0.048(stat)±0.034(syst) . The B0→ρ0ρ0 branching fraction, using the B0→ϕK⁎(892)0 decay as reference, is also reported as B(B0→ρ0ρ0)=(0.94±0.17(stat)±0.09(syst)±0.06(BF))×10−6
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