786 research outputs found
Robust Multi-Image HDR Reconstruction for the Modulo Camera
Photographing scenes with high dynamic range (HDR) poses great challenges to
consumer cameras with their limited sensor bit depth. To address this, Zhao et
al. recently proposed a novel sensor concept - the modulo camera - which
captures the least significant bits of the recorded scene instead of going into
saturation. Similar to conventional pipelines, HDR images can be reconstructed
from multiple exposures, but significantly fewer images are needed than with a
typical saturating sensor. While the concept is appealing, we show that the
original reconstruction approach assumes noise-free measurements and quickly
breaks down otherwise. To address this, we propose a novel reconstruction
algorithm that is robust to image noise and produces significantly fewer
artifacts. We theoretically analyze correctness as well as limitations, and
show that our approach significantly outperforms the baseline on real data.Comment: to appear at the 39th German Conference on Pattern Recognition (GCPR)
201
Consumersâ reactions to nutrition and ingredient labelling for wine â A cross-country discrete choice experiment
The purpose of this study is to examine consumers' reactions to the introduction of nutrition and ingredient labelling for wine, a product that is so far still exempt from mandatory nutrition and ingredient labelling. It also analyses the effect of positive and negative information about the use of ingredients in wine on consumers' choice. Representative samples for wine consumers from three distinctly different countries representing old and new wine markets (Australia, n = 745; Germany, n = 716; Italy, n = 715) completed a discrete choice experiment (DCE) with graphically simulated wine back labels. For each country, respondents were randomly allocated to a reference group and two different treatment conditions where they received newspaper-like information (positive, negative) before making choices. Results for the reference condition show that consumers across all three countries have a significant positive utility for detailed nutrition information. Instead, ingredient information only receives a positive utility in Italy, whereas German and Australian respondents do not receive utility from ingredient labelling. When consumers in the treatment group are confronted with negative media information the attribute importance of ingredients significantly increases across all three countries, clean labelled products without ingredients are preferred, and a significantly higher share of consumers in Germany and Italy prefer not to buy any wine. The treatment effect of positive media information on consumersâ wine choice is lower than that of negative information. The results of the study have implications for the pending new regulation of wine labelling and for communication strategies of the wine industry that should actively inform consumers about the necessity of ingredients in wine production
Real time monitoring of peptidoglycan synthesis by membrane-reconstituted penicillin binding proteins
Peptidoglycan is an essential component of the bacterial cell envelope that surrounds the cytoplasmic membrane to protect the cell from osmotic lysis. Important antibiotics such as ÎČ-lactams and glycopeptides target peptidoglycan biosynthesis. Class A penicillin-binding proteins (PBPs) are bifunctional membrane-bound peptidoglycan synthases that polymerize glycan chains and connect adjacent stem peptides by transpeptidation. How these enzymes work in their physiological membrane environment is poorly understood. Here, we developed a novel Förster resonance energy transfer-based assay to follow in real time both reactions of class A PBPs reconstituted in liposomes or supported lipid bilayers and applied this assay with PBP1B homologues from Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii in the presence or absence of their cognate lipoprotein activator. Our assay will allow unravelling the mechanisms of peptidoglycan synthesis in a lipid-bilayer environment and can be further developed to be used for high-throughput screening for new antimicrobials
Unusual magnetic-field dependence of partially frustrated triangular ordering in manganese tricyanomethanide
Manganese tricyanomethanide, Mn[C(CN)3]2, consists of two interpenetrating
three-dimensional rutile-like networks. In each network, the tridentate C(CN)3-
anion gives rise to superexchange interactions between the Mn2+ ions (S=5/2)
that can be mapped onto the "row model" for partially frustrated triangular
magnets. We present heat capacity measurements that reveal a phase transition
at T_N = 1.18K, indicative of magnetic ordering. The zero-field magnetically
ordered structure was solved from neutron powder diffraction data taken between
0.04 and 1.2 K. It consists of an incommensurate spiral with a temperature
independent propagation vector Q=(2Q 0 0)=(+/-0.622 0 0), where different signs
relate to the two different networks. This corresponds to (+/-0.311 +/-0.311 0)
in a quasi-hexagonal representation. The ordered moment mu=3.3mu_B is about 2/3
of the full Mn2+ moment. From the values of T_N and Q, the exchange parameters
J/k = 0.15 K and J'/J = 0.749 are estimated. The magnetic-field dependence of
the intensity of the Bragg reflection, measured for external fields
H||Q, indicates the presence of three different magnetic phases. We associate
them with the incommensurate spiral (H < 13.5 kOe), an intermediate phase (13.5
kOe 16 kOe)
proposed for related compounds. For increasing fields, Q continuously
approaches the value 1/3, corresponding to the commensurate magnetic structure
of the fully frustrated triangular lattice. This value is reached at H_c = 19
kOe. At this point, the field-dependence reverses and Q adopts a value of 0.327
at 26 kOe, the highest field applied in the experiment. Except for H_c, the
magnetic ordering is incommensurate in all three magnetic phases of
Mn[C(CN)3]2.Comment: accepted for publication in J. Phys.: Condens. Matte
Seasonal Dynamics of Dissolved Iron on the Antarctic Continental Shelf: Late-Fall Observations From the Terra Nova Bay and Ross Ice Shelf Polynyas
Over the Ross Sea shelf, annual primary production is limited by dissolved iron (DFe) supply. Here, a major source of DFe to surface waters is thought to be vertical resupply from the benthos, which is assumed most prevalent during winter months when katabatic winds drive sea ice formation and convective overturn in coastal polynyas, although the impact of these processes on water-column DFe distributions has not been previously documented. We collected hydrographic data and water-column samples for trace metals analysis in the Terra Nova Bay and Ross Ice Shelf polynyas during April-May 2017 (late austral fall). In the Terra Nova Bay polynya, we observed intense katabatic wind events, and surface mixed layer depths varied from similar to 250 to similar to 600 m over lateral distances \u3c10 km; there vertical mixing was just starting to excavate the dense, iron-rich Shelf Waters, and there was also evidence of DFe inputs at shallower depths in the water column. In the Ross Ice Shelf polynya, wind speeds were lower, mixed layers were \u3c300 m deep, and DFe distributions were similar to previous, late-summer observations, with concentrations elevated near the seafloor. Corresponding measurements of dissolved manganese and zinc, and particulate iron, manganese, and aluminum, suggest that deep DFe maxima and some mid-depth DFe maxima primarily reflect sedimentary inputs, rather than remineralization. Our data and model simulations imply that vertical resupply of DFe in the Ross Sea occurs mainly during mid-late winter, and may be particularly sensitive to changes in the timing and extent of sea ice production
How well does wind speed predict air-sea gas transfer in the sea ice zone? A synthesis of radon deficit profiles in the upper water column of the Arctic Ocean
Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 3696â3714, doi:10.1002/2016JC012460.We present 34 profiles of radon-deficit from the ice-ocean boundary layer of the Beaufort Sea. Including these 34, there are presently 58 published radon-deficit estimates of air-sea gas transfer velocity (k) in the Arctic Ocean; 52 of these estimates were derived from water covered by 10% sea ice or more. The average value of k collected since 2011 is 4.0â±â1.2 m dâ1. This exceeds the quadratic wind speed prediction of weighted kwsâ=â2.85 m dâ1 with mean-weighted wind speed of 6.4 m sâ1. We show how ice cover changes the mixed-layer radon budget, and yields an âeffective gas transfer velocity.â We use these 58 estimates to statistically evaluate the suitability of a wind speed parameterization for k, when the ocean surface is ice covered. Whereas the six profiles taken from the open ocean indicate a statistically good fit to wind speed parameterizations, the same parameterizations could not reproduce k from the sea ice zone. We conclude that techniques for estimating k in the open ocean cannot be similarly applied to determine k in the presence of sea ice. The magnitude of k through gaps in the ice may reach high values as ice cover increases, possibly as a result of focused turbulence dissipation at openings in the free surface. These 58 profiles are presently the most complete set of estimates of k across seasons and variable ice cover; as dissolved tracer budgets they reflect air-sea gas exchange with no impact from air-ice gas exchange.NSF Arctic Natural Sciences program Grant Number: 12035582017-11-0
Protein Pattern Formation
Protein pattern formation is essential for the spatial organization of many
intracellular processes like cell division, flagellum positioning, and
chemotaxis. A prominent example of intracellular patterns are the oscillatory
pole-to-pole oscillations of Min proteins in \textit{E. coli} whose biological
function is to ensure precise cell division. Cell polarization, a prerequisite
for processes such as stem cell differentiation and cell polarity in yeast, is
also mediated by a diffusion-reaction process. More generally, these functional
modules of cells serve as model systems for self-organization, one of the core
principles of life. Under which conditions spatio-temporal patterns emerge, and
how these patterns are regulated by biochemical and geometrical factors are
major aspects of current research. Here we review recent theoretical and
experimental advances in the field of intracellular pattern formation, focusing
on general design principles and fundamental physical mechanisms.Comment: 17 pages, 14 figures, review articl
- âŠ