403 research outputs found
NeRF: Neural Radiance Field in 3D Vision, A Comprehensive Review
Neural Radiance Field (NeRF), a new novel view synthesis with implicit scene
representation has taken the field of Computer Vision by storm. As a novel view
synthesis and 3D reconstruction method, NeRF models find applications in
robotics, urban mapping, autonomous navigation, virtual reality/augmented
reality, and more. Since the original paper by Mildenhall et al., more than 250
preprints were published, with more than 100 eventually being accepted in tier
one Computer Vision Conferences. Given NeRF popularity and the current interest
in this research area, we believe it necessary to compile a comprehensive
survey of NeRF papers from the past two years, which we organized into both
architecture, and application based taxonomies. We also provide an introduction
to the theory of NeRF based novel view synthesis, and a benchmark comparison of
the performance and speed of key NeRF models. By creating this survey, we hope
to introduce new researchers to NeRF, provide a helpful reference for
influential works in this field, as well as motivate future research directions
with our discussion section
Mesoscale covariance of transport and CO2 fluxes: Evidence from observations and simulations using the WRF-VPRM coupled atmosphere-biosphere model
We developed a modeling system which combines a mesoscale meteorological model, the Weather Research and Forecasting (WRF) model, with a diagnostic biospheric model, the Vegetation Photosynthesis and Respiration (VPRM). The WRF-VPRM modeling system was designed to realistically simulate high-resolution atmospheric CO<sub>2</sub> concentration fields. In the system, WRF takes into account anthropogenic and biospheric CO<sub>2</sub> fluxes and realistic initial and boundary conditions for CO<sub>2</sub> from a global model. The system uses several âtaggedâ tracers for CO<sub>2</sub> fields from different sources. VPRM uses meteorological fields from WRF and high-resolution satellite indices to simulate biospheric CO<sub>2</sub> fluxes with realistic spatiotemporal patterns. Here we present results from the application of the model for interpretation of measurements made within the CarboEurope Regional Experiment Strategy (CERES). Simulated fields of meteorological variables and CO<sub>2</sub> were compared against ground-based and airborne observations. In particular, the characterization by aircraft measurements turned out to be crucial for the model evaluation. The comparison revealed that the model is able to capture the main observed features in the CO<sub>2</sub> distribution reasonably well. The simulations showed that daytime CO<sub>2</sub> measurements made at coastal stations can be strongly affected by land breeze and subsequent sea breeze transport of CO<sub>2</sub> respired from the vegetation during the previous night, which can lead to wrong estimates when such data are used in inverse studies. The results also show that WRF-VPRM is an effective modeling tool for addressing the near-field variability of CO<sub>2</sub> fluxes and concentrations for observing stations around the globe
Learning to communicate computationally with Flip: a bi-modal programming language for game creation
Teaching basic computational concepts and skills to school children is currently a curricular focus in many countries. Running parallel to this trend are advances in programming environments and teaching methods which aim to make computer science more accessible, and more motivating. In this paper, we describe the design and evaluation of Flip, a programming language that aims to help 11â15 year olds develop computational skills through creating their own 3D role-playing games. Flip has two main components: 1) a visual language (based on an interlocking blocks design common to many current visual languages), and 2) a dynamically updating natural language version of the script under creation. This programming-language/natural-language pairing is a unique feature of Flip, designed to allow learners to draw upon their familiarity with natural language to âdecode the codeâ. Flip aims to support young people in developing an understanding of computational concepts as well as the skills to use and communicate these concepts effectively. This paper investigates the extent to which Flip can be used by young people to create working scripts, and examines improvements in their expression of computational rules and concepts after using the tool. We provide an overview of the design and implementation of Flip before describing an evaluation study carried out with 12â13 year olds in a naturalistic setting. Over the course of 8 weeks, the majority of students were able to use Flip to write small programs to bring about interactive behaviours in the games they created. Furthermore, there was a significant improvement in their computational communication after using Flip (as measured by a pre/post-test). An additional finding was that girls wrote more, and more complex, scripts than did boys, and there was a trend for girls to show greater learning gains relative to the boys
Protein kinase CÎŽ oxidation contributes to ERK inactivation in lupus T cells
Objective CD4+ T cells from patients with active lupus have impaired ERK pathway signaling that decreases DNA methyltransferase expression, resulting in DNA demethylation, overexpression of immune genes, and autoimmunity. The ERK pathway defect is due to impaired phosphorylation of T 505 in the protein kinase CÎŽ (PKCÎŽ) activation loop. However, the mechanisms that prevent PKCÎŽ T 505 phosphorylation in lupus T cells are unknown. Others have reported that oxidative modifications, and nitration in particular, of T cells as well as serum proteins correlate with lupus disease activity. We undertook this study to test our hypothesis that nitration inactivates PKCÎŽ, contributing to impaired ERK pathway signaling in lupus T cells. Methods CD4+ T cells were purified from lupus patients and controls and then stimulated with phorbol myristate acetate (PMA). Signaling protein levels, nitration, and phosphorylation were quantitated by immunoprecipitation and immunoblotting of T cell lysates. Transfections were performed by electroporation. Results Treating CD4+ T cells with peroxynitrite nitrated PKCÎŽ, preventing PKCÎŽ T 505 phosphorylation and inhibiting ERK pathway signaling similar to that observed in lupus T cells. Patients with active lupus had higher nitrated T cell PKCÎŽ levels than did controls, which correlated directly with disease activity, and antinitrotyrosine immunoprecipitations demonstrated that nitrated PKCÎŽ, but not unmodified PKCÎŽ, was refractory to PMAâstimulated T 505 phosphorylation, similar to PKCÎŽ in peroxynitriteâtreated cells. Conclusion Oxidative stress causes PKCÎŽ nitration, which prevents its phosphorylation and contributes to the decreased ERK signaling in lupus T cells. These results identify PKCÎŽ as a link between oxidative stress and the T cell epigenetic modifications in lupus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93545/1/34503_ftp.pd
An Analytical Survey of Provenance Sanitization
Security is likely becoming a critical factor in the future adoption of
provenance technology, because of the risk of inadvertent disclosure of
sensitive information. In this survey paper we review the state of the art in
secure provenance, considering mechanisms for controlling access, and the
extent to which these mechanisms preserve provenance integrity. We examine
seven systems or approaches, comparing features and identifying areas for
future work.Comment: To appear, IPAW 201
Treatment outcome of new pulmonary tuberculosis in Guangzhou, China 1993â2002: a register-based cohort study
<p>Abstract</p> <p>Background</p> <p>Completion of treatment for tuberculosis (TB) is of utmost priority for TB control programs. The aims of this study were to evaluate the treatment outcome of TB cases registered in Guangzhou during the period 1993â2002, and to identify factors associated with treatment success.</p> <p>Methods</p> <p>Two (of eight) districts in Guangzhou were selected randomly as objects of study and their surveillance database was analyzed to assess the treatment outcome and identify factors associated with treatment success for TB cases registered in Guangzhou. Six treatment outcome criteria were assessed based on guidelines set by the World Health Organization (WHO). Logistic regression was used to estimate risk factors for treatment outcome.</p> <p>Results</p> <p>A total of 6743 pulmonary tuberculosis cases (4903 males, 1840 females) were included in this study. The treatment success rate (including cured and complete treatment) was 88% (95%CI 87%â89%). One hundred and eight-six (2.8%) patients died and 401 (5.9%) patients defaulted treatment. In multivariate analysis, treatment success was found to be associated with young age, lack of cavitation and compliance with treatment.</p> <p>Conclusion</p> <p>The total treatment success rate in the current study was similar to the WHO target for all smear positive cases, while the failure rate and the default rate in 2002 were slightly higher. Good care of elderly patients, early diagnosis of cavitation and compliance with treatment could improve the success rate of TB treatment.</p
Terminal uranium(V/VI) nitride activation of carbon dioxide and carbon disulfide: factors governing diverse and well-defined cleavage and redox reactions
The reactivity of terminal uranium(V/VI) nitrides with CE2 (E=O, S) is presented. Well-defined C=E cleavage followed by zero-, one-, and two-electron redox events is observed. The uranium(V) nitride [U(TrenTIPS)(N)][K(B15C5)2] (1, TrenTIPS=N(CH2CH2NSiiPr3)3; B15C5=benzo-15-crown-5) reacts with CO2 to give [U(TrenTIPS)(O)(NCO)][K(B15C5)2] (3), whereas the uranium(VI) nitride [U(TrenTIPS)(N)] (2) reacts with CO2 to give isolable [U(TrenTIPS)(O)(NCO)] (4); complex 4 rapidly decomposes to known [U(TrenTIPS)(O)] (5) with concomitant formation of N2 and CO proposed, with the latter trapped as a vanadocene adduct. In contrast, 1 reacts with CS2 to give [U(TrenTIPS)(Îș2-CS3)][K(B15C5)2] (6), 2, and [K(B15C5)2][NCS] (7), whereas 2 reacts with CS2 to give [U(TrenTIPS)(NCS)] (8) and âSâ, with the latter trapped as Ph3PS. Calculated reaction profiles reveal outer-sphere reactivity for uranium(V) but inner-sphere mechanisms for uranium(VI); despite the wide divergence of products the initial activation of CE2 follows mechanistically related pathways, providing insight into the factors of uranium oxidation state, chalcogen, and NCE groups that govern the subsequent divergent redox reactions that include common one-electron reactions and a less-common two-electron redox event. Caution, we suggest, is warranted when utilising CS2 as a reactivity surrogate for CO2
A global evaluation of the regional spatial variability of column integrated CO 2 distributions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95294/1/jgrd14612.pd
The inverse-trans-influence in tetravalent lanthanide and actinide bis(carbene) complexes
Across the periodic table the trans-influence operates, whereby tightly bonded ligands selectively lengthen mutually trans metalâligand bonds. Conversely, in high oxidation state actinide complexes the inverse-trans-influence operates, where normally cis strongly donating ligands instead reside trans and actually reinforce each other. However, because the inversetrans-influence is restricted to high-valent actinyls and a few uranium(V/VI) complexes, it has had limited scope in an area with few unifying rules. Here we report tetravalent cerium, uranium and thorium bis(carbene) complexes with trans CÂŒMÂŒC cores where experimental and theoretical data suggest the presence of an inverse-trans-influence. Studies of hypothetical praseodymium(IV) and terbium(IV) analogues suggest the inverse-trans-influence may extend to these ions but it also diminishes significantly as the 4f orbitals are populated. This work suggests that the inverse-trans-influence may occur beyond high oxidation state 5f metals and hence could encompass mid-range oxidation state actinides and lanthanides. Thus, the inverse-trans-influence might be a more general f-block principle
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