3,456 research outputs found
On the welfare cost of consumption fluctuations in the presence of memorable goods : [version october 17, 2013]
We propose a new classification of consumption goods into nondurable goods, durable goods and a new class which we call âmemorableâ goods. A good is memorable if a consumer can draw current utility from its past consumption experience through memory. We construct a novel consumption-savings model in which a consumer has a well-defined preference ordering over both nondurable goods and memorable goods. Memorable goods consumption differs from nondurable goods consumption in that current memorable goods consumption may also impact future utility through the accumulation process of the stock of memory. In our model, households optimally choose a lumpy profile of memorable goods consumption even in a frictionless world. Using Consumer Expenditure Survey data, we then document levels and volatilities of different groups of consumption goods expenditures, as well as their expenditure patterns, and show that the expenditure patterns on memorable goods indeed differ significantly from those on nondurable and durable goods. Finally, we empirically evaluate our modelâs predictions with respect to the welfare cost of consumption fluctuations and conduct an excess-sensitivity test of the consumption response to predictable income changes. We find that (i) the welfare cost of household-level consumption fluctuations may be overstated by 1.7 percentage points (11.9% points as opposed to 13.6% points of permanent consumption) if memorable goods are not appropriately accounted for; (ii) the finding of excess sensitivity of consumption documented in important papers of the literature might be entirely due to the presence of memorable goods
Non-bisphosphonate inhibitors of isoprenoid biosynthesis identified via computer-aided drug design.
The relaxed complex scheme, a virtual-screening methodology that accounts for protein receptor flexibility, was used to identify a low-micromolar, non-bisphosphonate inhibitor of farnesyl diphosphate synthase. Serendipitously, we also found that several predicted farnesyl diphosphate synthase inhibitors were low-micromolar inhibitors of undecaprenyl diphosphate synthase. These results are of interest because farnesyl diphosphate synthase inhibitors are being pursued as both anti-infective and anticancer agents, and undecaprenyl diphosphate synthase inhibitors are antibacterial drug leads
Detection of covalent enzyme-substrate complexes of nitrilase by ion-spray mass spectroscopy
AbstractNitrilase from Rhodococcus ATCC 39484 was found to consist of two species of Mr 40 258 ±2 and 40 388 ±2 Da. When the enzyme was incubated with nitrile substrates and the reaction quenched with acid, higher Mr, species were observed. The mass differences were consistent with addition of a substrate molecule to each species. These results represent the first reported demonstration that this, or any other nitrilase forms a covalent intermediate with its substrates. The observation that the intermediate, suggested to be either a thioimidate or an acylenzyme, can be trapped by acidification indicates that the rate of breakdown of the intermediate is rate-limiting
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Modification of Transition-Metal Redox by Interstitial Water in Hexacyanometalate Electrodes for Sodium-Ion Batteries.
A sodium-ion battery (SIB) solution is attractive for grid-scale electrical energy storage. Low-cost hexacyanometalate is a promising electrode material for SIBs because of its easy synthesis and open framework. Most hexacyanometalate-based SIBs work with aqueous electrolyte, and interstitial water in the material has been found to strongly affect the electrochemical profile, but the mechanism remains elusive. Here we provide a comparative study of the transition-metal redox in hexacyanometalate electrodes with and without interstitial water based on soft X-ray absorption spectroscopy and theoretical calculations. We found distinct transition-metal redox sequences in hydrated and anhydrated NaxMnFe(CN)6·zH2O. The Fe and Mn redox in hydrated electrodes are separated and are at different potentials, leading to two voltage plateaus. On the contrary, mixed Fe and Mn redox in the same potential range is found in the anhydrated system. This work reveals for the first time how transition-metal redox in batteries is strongly affected by interstitial molecules that are seemingly spectators. The results suggest a fundamental mechanism based on three competing factors that determine the transition-metal redox potentials. Because most hexacyanometalate electrodes contain water, this work directly reveals the mechanism of how interstitial molecules could define the electrochemical profile, especially for electrodes based on transition-metal redox with well-defined spin states
Differences in perception of dysentery and enteric fever and willingness to receive vaccines among rural residents in China.
BACKGROUND: Enteric diseases including dysentery and enteric fever remain significant public health problems in China. While vaccines offer great potential in controlling these diseases, greater understanding of factors influencing acceptance of vaccines is needed to create effective enteric disease control programs in rural China. DESIGN: Cross-sectional quantitative study with randomly sampled households from two sites in China, one experiencing high rates of shigellosis (Zengding) and the other of typhoid/paratyphoid (Lingchuan). METHODS: Sociobehavioral survey data were collected through face-to-face interviews from 501 respondents (56% female) in Zhengding regarding dysentery and 624 in Lingchuan (51% female) regarding enteric fever. Vaccine acceptability was measured by expressed need for vaccination and willingness to pay. Comparative and associative analyses were conducted to assess disease perception, vaccination service satisfaction, likelihood of improvements in water and sanitation, and vaccine acceptability. RESULTS: Nearly all respondents in Lingchuan considered enteric fever to be prevalent in the community, while only one half of the respondents in Zhengding considered dysentery to be problematic (p < 0.01). Nevertheless, more respondents in Zhengding were fearful that a household member would acquire dysentery than were Lingchuan respondents worried that a household member would acquire enteric fever (p < 0.01). Perceived vulnerability of specific subgroups (odds ratios ranging from 1.6 to 8.1), knowing someone who died of the disease (odds ratio reached infinity) and satisfaction with past vaccination services (odds ratios reached infinity) were consistently associated with perceived need for vaccines of target populations of all age groups while the association between perception of sanitary improvement and vaccine need was limited. Perceived need for a vaccine was associated with willingness to pay for the vaccine. CONCLUSIONS: Perceptions of enhanced vulnerability of specific subgroups to a disease and satisfactory experiences with vaccination services may increase the perceived need for a vaccine, leading to increased willingness to pay for vaccine. Vaccines are not perceived as important for the elderly
Finding the Needle in a Haystack: Detecting Bug Occurrences in Gameplay Videos
The presence of bugs in video games can bring significant consequences for
developers. To avoid these consequences, developers can leverage gameplay
videos to identify and fix these bugs. Video hosting websites such as YouTube
provide access to millions of game videos, including videos that depict bug
occurrences, but the large amount of content can make finding bug instances
challenging. We present an automated approach that uses machine learning to
predict whether a segment of a gameplay video contains the depiction of a bug.
We analyzed 4,412 segments of 198 gameplay videos to predict whether a segment
contains an instance of a bug. Additionally, we investigated how our approach
performs when applied across different specific genres of video games and on
videos from the same game. We also analyzed the videos in the dataset to
investigate what characteristics of the visual features might explain the
classifier's prediction. Finally, we conducted a user study to examine the
benefits of our automated approach against a manual analysis. Our findings
indicate that our approach is effective at detecting segments of a video that
contain bugs, achieving a high F1 score of 0.88, outperforming the current
state-of-the-art technique for bug classification of gameplay video segments
A p-type Heusler compound: Growth, structure, and properties of epitaxial thin NiYBi films on MgO(100)
Epitaxial semiconducting NiYBi thin films were directly prepared on MgO(100)
substrates by magnetron sputtering. The intensity ratio of the (200) and (400)
diffraction peaks, I(200)/I(400) = 2.93, was close to the theoretical value
(3.03). The electronic structure of NiYBi was calculated using WIEN2k and a
narrow indirect band gap of width 210 meV was found. The valence band spectra
of the films obtained by linear dichroism in hard X-ray photoelectron
spectroscopy exhibit clear structures that are in good agreement with the
calculated band structure of NiYBi
Constraints on the binary black hole hypothesis for system LB-1
At about 70 solar masses, the recently-discovered dark object orbited by a B-type star in the system LB-1 is difficult to understand as the end point of standard stellar evolution, except as a binary black hole (BBH). LB-1 shows a strong, broad H-alpha emission line that is best attributed to a gaseous disk surrounding the dark mass. We use the observed H-alpha line shape, particularly its wing extension, to constrain the inner radius of the disk and thereby the separation of a putative BBH. The hypothesis of a current BBH is effectively ruled out on the grounds that its merger time must be a small fraction of the current age of the B star. The hypothesis of a previous BBH that merged to create the current dark mass is also effectively ruled out by the low orbital eccentricity, due to the combination of mass loss and kick resulted from gravitational wave emission in any past merger. We conclude that the current dark mass is a single black hole produced by the highly mass-conserving, monolithic collapse of a massive star
Instant Photorealistic Style Transfer: A Lightweight and Adaptive Approach
In this paper, we propose an Instant Photorealistic Style Transfer (IPST)
approach, designed to achieve instant photorealistic style transfer on
super-resolution inputs without the need for pre-training on pair-wise datasets
or imposing extra constraints. Our method utilizes a lightweight StyleNet to
enable style transfer from a style image to a content image while preserving
non-color information. To further enhance the style transfer process, we
introduce an instance-adaptive optimization to prioritize the photorealism of
outputs and accelerate the convergence of the style network, leading to a rapid
training completion within seconds. Moreover, IPST is well-suited for
multi-frame style transfer tasks, as it retains temporal and multi-view
consistency of the multi-frame inputs such as video and Neural Radiance Field
(NeRF). Experimental results demonstrate that IPST requires less GPU memory
usage, offers faster multi-frame transfer speed, and generates photorealistic
outputs, making it a promising solution for various photorealistic transfer
applications.Comment: 8 pages (reference excluded), 6 figures, 4 table
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