MetaAvatar: Learning Animatable Clothed Human Models from Few Depth Images

In this paper, we aim to create generalizable and controllable neural signed distance fields (SDFs) that represent clothed humans from monocular depth observations. Recent advances in deep learning, especially neural implicit representations, have enabled human shape reconstruction and controllable avatar generation from different sensor inputs. However, to generate realistic cloth deformations from novel input poses, watertight meshes or dense full-body scans are usually needed as inputs. Furthermore, due to the difficulty of effectively modeling pose-dependent cloth deformations for diverse body shapes and cloth types, existing approaches resort to per-subject/cloth-type optimization from scratch, which is computationally expensive. In contrast, we propose an approach that can quickly generate realistic clothed human avatars, represented as controllable neural SDFs, given only monocular depth images. We achieve this by using meta-learning to learn an initialization of a hypernetwork that predicts the parameters of neural SDFs. The hypernetwork is conditioned on human poses and represents a clothed neural avatar that deforms non-rigidly according to the input poses. Meanwhile, it is meta-learned to effectively incorporate priors of diverse body shapes and cloth types and thus can be much faster to fine-tune, compared to models trained from scratch. We qualitatively and quantitatively show that our approach outperforms state-of-the-art approaches that require complete meshes as inputs while our approach requires only depth frames as inputs and runs orders of magnitudes faster. Furthermore, we demonstrate that our meta-learned hypernetwork is very robust, being the first to generate avatars with realistic dynamic cloth deformations given as few as 8 monocular depth frames.Comment: 17 pages, 9 figures. Project page: https://neuralbodies.github.io/metavatar

Optimal number of pigments in photosynthetic complexes

We study excitation energy transfer in a simple model of photosynthetic complex. The model, described by Lindblad equation, consists of pigments interacting via dipole-dipole interaction. Overlapping of pigments induces an on-site energy disorder, providing a mechanism for blocking the excitation transfer. Based on the average efficiency as well as robustness of random configurations of pigments, we calculate the optimal number of pigments that should be enclosed in a pigment-protein complex of a given size. The results suggest that a large fraction of pigment configurations are efficient as well as robust if the number of pigments is properly chosen. We compare optimal results of the model to the structure of pigment-protein complexes as found in nature, finding good agreement.Comment: 20 pages, 7 figures; v2.: new appendix, published versio

Design and Development of an Integrated Web-based System for Tropical Rainfall Monitoring

This study is about the design and development of an integrated web-based system for tropical rainfall monitoring. The system gathers data using a network of low-cost, Android-based acoustic rainfall sensors, a nationwide infrastructure of 5 GHz wireless broadband links, and remote weather stations. The low-cost Android-based acoustic rainfall sensors are deployed at high densities over a local area and the 5 GHz wireless broadband sensors gather rainfall information on a nationwide scale. The sensor network provides information about spatial-variations that are characteristics of tropical rain rates, and complement data from the scarcely deployed remote weather stations. Gathered data is then processed and displayed on a web interface

Antibiotic Resistance Genes in the Human-Impacted Environment : A One Health Perspective

Antibiotic resistance and its environmental component are gaining more attention as part of combating the growing healthcare crisis. The One Health framework, promulgated by many global health agencies, recognizes that antimicrobial resistance is a truly inter-domain problem in which human health, animal agriculture, and the environment are the core and interrelated components. This prospectus presents the status and issues relevant to the environmental component of antibiotic resistance, namely, the needs for advancing surveillance methodology: the environmental reservoirs and sources of resistance, namely, urban wastewater treatment plants, aquaculture production systems, soil receiving manure and biosolid, and the atmosphere which includes longer range dispersal. Recently, much work has been done describing antibiotic resistance genes in various environments; now quantitative, mechanistic, and hypothesis-driven studies are needed to identify practices that reduce real risks and maintain the effectiveness of our current antibiotics as long as possible. Advanced deployable detection methods for antibiotic resistance in diverse environmental samples are needed in order to provide the surveillance information to identify risks and define barriers that can reduce risks. Also needed are practices that reduce antibiotic use and thereby reduce selection for resistance, as well as practices that limit the dispersal of or destroy antibiotic-resistant bacteria or their resistance genes that are feasible for these varied environmental domains.Peer reviewe

Effects of Global and Regional Dust Storms on the Martian Hot O Corona and Photochemical Loss

We examine here for the first time the effects of both global and regional dust storms on the formation of the Martian hot O corona and associated photochemical loss of O. Our study is conducted by utilizing our integrated model framework, which couples our Martian hot O corona model with a multifluid magnetohydrodynamic model for Mars for the dusty and clear atmospheric condition cases. We present our results with the most up‐to‐date cross sections for the O(3P)‐CO2 collisions. The main effect of dust storms on the ionosphere is the upward shift of the ionosphere on the dayside, which results in an increase in production of hot O at all altitudes above the ionospheric peak. However, the dust‐induced inflation of the neutral upper atmosphere results in an enhancement in collisional loss of hot O and thus effectively suppresses the hot O density, reducing the global photochemical loss rate by ~28% for the global dust storm scenario. The relative density structure of the hot O corona does not show any significant changes, while its magnitude decreases at all altitudes.Key PointsWe investigated the effect of dust storms on photochemical escape from Mars using up‐to‐date cross sections for O‐CO2 collisionsThe storm‐induced upward shift of the ionosphere causes increased production of hot O and efficient thermalization occurs by the inflated thermosphereThe net result is a global photochemical escape rate that is suppressed by ~28% during the global dust storm scenarioPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154658/1/jgra55566_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154658/2/jgra55566.pd

Kinesin Is an Evolutionarily Fine-Tuned Molecular Ratchet-and-Pawl Device of Decisively Locked Direction

Conventional kinesin is a dimeric motor protein that transports membranous organelles toward the plus-end of microtubules (MTs). Individual kinesin dimers show steadfast directionality and hundreds of consecutive steps, yetthe detailed physical mechanism remains unclear. Here we compute free energies for the entire dimer-MT system for all possible interacting configurations by taking full account of molecular details. Employing merely first principles and several measured binding and barrier energies, the system-level analysis reveals insurmountable energy gaps between configurations, asymmetric ground state caused by mechanically lifted configurational degeneracy, and forbidden transitions ensuring coordination between both motor domains for alternating catalysis. This wealth of physical effects converts a kinesin dimer into a molecular ratchet-and-pawl device, which determinedly locks the dimer's movement into the MT plus-end and ensures consecutive steps in hand-over-hand gait.Under a certain range of extreme loads, however, the ratchet-and-pawl device becomes defective but not entirely abolished to allow consecutive back-steps. This study yielded quantitative evidence that kinesin's multiple molecular properties have been evolutionarily adapted to fine-tune the ratchet-and-pawl device so as to ensure the motor's distinguished performance.Comment: 10 printed page

Serbian Citizens’ Opinion on the COVID-19 Epidemic

Aim: The Centre for International Public Policy has undertaken a public opinion research in which we tested the opinions of the citizens of Serbia on the coronavirus epidemic. The respondents had the opportunity to express their opinion on measures undertaken by the Serbian Government to combat the virus, to state their trust in the media, as well as the health system in general. In addition, we tested the prevalence of different conspiracy theories among citizens, whether the pandemic gave China a new image in the minds of the people and, most importantly, the level of solidarity among Serbian citizens as well as within the European / international community as a whole. Methods: In seven days, from 8-15th April 2020, we gathered a convenient sample of N=5989 respondents, which makes this the largest public opinion research project in Serbia on the topic of COVID-19 since the start of the epidemic. The electronic questionnaire consisted of 24 questions of mixed and closed type. Results: The findings of this research suggest that citizens of Serbia are not afraid of COVID-19, but are nevertheless cautious (86%). The percentage of those willing to consult a doctor when they notice any symptoms lies at 70%. Half of the respondents do not believe in alternative theories regarding the origin of the COVID-19 virus. The majority of the respondents (55%) hold government officials accountable for spreading panic through public speeches and daily public addresses. Moreover, 60% of the respondents do not trust the Serbian media outlets that are currently reporting on the COVID-19 pandemic. Furthermore, over half of the respondents are prepared to report their neighbour when he or she is coming from abroad and violates the obligation to self-isolate. However, mostly due to the significant fines, 65% of the respondents would not report the elderly when they are breaking the limited-movement restriction measures. Conclusion: As before the epidemic, opinions of the Serbian population on current topics are somewhat polarized. Although the majority of the respondents are cautious, a significant number also believes in conspiracy theories and does not fully trust the information provided by the media or the government.                                                                               &nbsp

Serbian Citizens’ Opinion on the COVID-19 Epidemic

Aim: The Centre for International Public Policy has undertaken a public opinion research in which we tested the opinions of the citizens of Serbia on the coronavirus epidemic. The respondents had the opportunity to express their opinion on measures undertaken by the Serbian Government to combat the virus, to state their trust in the media, as well as the health system in general. In addition, we tested the prevalence of different conspiracy theories among citizens, whether the pandemic gave China a new image in the minds of the people and, most importantly, the level of solidarity among Serbian citizens as well as within the European / international community as a whole. Methods: In seven days, from 8-15th April 2020, we gathered a convenient sample of N=5989 respondents, which makes this the largest public opinion research project in Serbia on the topic of COVID-19 since the start of the epidemic. The electronic questionnaire consisted of 24 questions of mixed and closed type. Results: The findings of this research suggest that citizens of Serbia are not afraid of COVID-19, but are nevertheless cautious (86%). The percentage of those willing to consult a doctor when they notice any symptoms lies at 70%. Half of the respondents do not believe in alternative theories regarding the origin of the COVID-19 virus. The majority of the respondents (55%) hold government officials accountable for spreading panic through public speeches and daily public addresses. Moreover, 60% of the respondents do not trust the Serbian media outlets that are currently reporting on the COVID-19 pandemic. Furthermore, over half of the respondents are prepared to report their neighbour when he or she is coming from abroad and violates the obligation to self-isolate. However, mostly due to the significant fines, 65% of the respondents would not report the elderly when they are breaking the limited-movement restriction measures. Conclusion: As before the epidemic, opinions of the Serbian population on current topics are somewhat polarized. Although the majority of the respondents are cautious, a significant number also believes in conspiracy theories and does not fully trust the information provided by the media or the government.                            &nbsp

Nonlinear Elasticity in Biological Gels

Unlike most synthetic materials, biological materials often stiffen as they are deformed. This nonlinear elastic response, critical for the physiological function of some tissues, has been documented since at least the 19th century, but the molecular structure and the design principles responsible for it are unknown. Current models for this response require geometrically complex ordered structures unique to each material. In this Article we show that a much simpler molecular theory accounts for strain stiffening in a wide range of molecularly distinct biopolymer gels formed from purified cytoskeletal and extracellular proteins. This theory shows that systems of semi-flexible chains such as filamentous proteins arranged in an open crosslinked meshwork invariably stiffen at low strains without the need for a specific architecture or multiple elements with different intrinsic stiffnesses.Comment: 23 pages, 5 figures, submitted to Natur

Density-dependence of functional development in spiking cortical networks grown in vitro

During development, the mammalian brain differentiates into specialized regions with distinct functional abilities. While many factors contribute to functional specialization, we explore the effect of neuronal density on the development of neuronal interactions in vitro. Two types of cortical networks, dense and sparse, with 50,000 and 12,000 total cells respectively, are studied. Activation graphs that represent pairwise neuronal interactions are constructed using a competitive first response model. These graphs reveal that, during development in vitro, dense networks form activation connections earlier than sparse networks. Link entropy analysis of dense net- work activation graphs suggests that the majority of connections between electrodes are reciprocal in nature. Information theoretic measures reveal that early functional information interactions (among 3 cells) are synergetic in both dense and sparse networks. However, during later stages of development, previously synergetic relationships become primarily redundant in dense, but not in sparse networks. Large link entropy values in the activation graph are related to the domination of redundant ensembles in late stages of development in dense networks. Results demonstrate differences between dense and sparse networks in terms of informational groups, pairwise relationships, and activation graphs. These differences suggest that variations in cell density may result in different functional specialization of nervous system tissue in vivo.Comment: 10 pages, 7 figure