Effect of long-term starvation on the survival, recovery, and carbon utilization profiles of a bovine Escherichia coli O157:H7 isolate from New Zealand

The ability to maintain a dual lifestyle of colonizing the ruminant gut and surviving in nonhost environments once shed is key to the success of Escherichia coli O157:H7 as a zoonotic pathogen. Both physical and biological conditions encountered by the bacteria are likely to change during the transition between host and nonhost environments. In this study, carbon starvation at suboptimal temperatures in nonhost environments was simulated by starving a New Zealand bovine E. coli O157:H7 isolate in phosphate-buffered saline at 4 and 15°C for 84 days. Recovery of starved cells on media with different nutrient availabilities was monitored under aerobic and anaerobic conditions. We found that the New Zealand bovine E. coli O157:H7 isolate was able to maintain membrane integrity and viability over 84 days and that the level of recovery depended on the nutrient level of the recovery medium as well as the starvation temperature. In addition, a significant difference in carbon utilization was observed between starved and nonstarved cells

Effect of long-term starvation on the survival, recovery, and carbon utilization profiles of a bovine Escherichia coli O157:H7 isolate from New Zealand

The ability to maintain a dual lifestyle of colonizing the ruminant gut and surviving in nonhost environments once shed is key to the success of Escherichia coli O157:H7 as a zoonotic pathogen. Both physical and biological conditions encountered by the bacteria are likely to change during the transition between host and nonhost environments. In this study, carbon starvation at suboptimal temperatures in nonhost environments was simulated by starving a New Zealand bovine E. coli O157:H7 isolate in phosphate-buffered saline at 4 and 15°C for 84 days. Recovery of starved cells on media with different nutrient availabilities was monitored under aerobic and anaerobic conditions. We found that the New Zealand bovine E. coli O157:H7 isolate was able to maintain membrane integrity and viability over 84 days and that the level of recovery depended on the nutrient level of the recovery medium as well as the starvation temperature. In addition, a significant difference in carbon utilization was observed between starved and nonstarved cells

Dual input neural networks for positional sound source localization

In many signal processing applications, metadata may be advantageously used in conjunction with a high dimensional signal to produce a desired output. In the case of classical Sound Source Localization (SSL) algorithms, information from a high dimensional, multichannel audio signals received by many distributed microphones is combined with information describing acoustic properties of the scene, such as the microphones' coordinates in space, to estimate the position of a sound source. We introduce Dual Input Neural Networks (DI-NNs) as a simple and effective way to model these two data types in a neural network. We train and evaluate our proposed DI-NN on scenarios of varying difficulty and realism and compare it against an alternative architecture, a classical Least-Squares (LS) method as well as a classical Convolutional Recurrent Neural Network (CRNN). Our results show that the DI-NN significantly outperforms the baselines, achieving a five times lower localization error than the LS method and two times lower than the CRNN in a test dataset of real recordings

Evolution of Massive Protostars via Disk Accretion

Mass accretion onto (proto-)stars at high accretion rates > 10^-4 M_sun/yr is expected in massive star formation. We study the evolution of massive protostars at such high rates by numerically solving the stellar structure equations. In this paper we examine the evolution via disk accretion. We consider a limiting case of "cold" disk accretion, whereby most of the stellar photosphere can radiate freely with negligible backwarming from the accretion flow, and the accreting material settles onto the star with the same specific entropy as the photosphere. We compare our results to the calculated evolution via spherically symmetric accretion, the opposite limit, whereby the material accreting onto the star contains the entropy produced in the accretion shock front. We examine how different accretion geometries affect the evolution of massive protostars. For cold disk accretion at 10^-3 M_sun/yr the radius of a protostar is initially small, about a few R_sun. After several solar masses have accreted, the protostar begins to bloat up and for M \simeq 10 M_sun the stellar radius attains its maximum of 30 - 400 R_sun. The large radius about 100 R_sun is also a feature of spherically symmetric accretion at the same accreted mass and accretion rate. Hence, expansion to a large radius is a robust feature of accreting massive protostars. At later times the protostar eventually begins to contract and reaches the Zero-Age Main-Sequence (ZAMS) for M \simeq 30 M_sun, independent of the accretion geometry. For accretion rates exceeding several 10^-3 M_sun/yr the protostar never contracts to the ZAMS. The very large radius of several 100s R_sun results in a low effective temperature and low UV luminosity of the protostar. Such bloated protostars could well explain the existence of bright high-mass protostellar objects, which lack detectable HII regions.Comment: 20 pages, 16 figure

Psychosocial Factors Related to the Intergenerational Transmission of Externalizing Behaviors in Early Midlife

Background: To study the intergenerational transmission of externalizing behaviors. Methods: Participants came from a community-based random sample of residents in two upstate New York counties (N = 548). Data were collected from mothers at mean age 40 and from their children from adolescence (mean age = 14, SD = 2.8) to early midlife (mean age = 43, SD = 2.8) at seven time points. Structural equation modeling (SEM) was used to study the psychosocial factors as related to externalizing behaviors in early midlife. Results: First, maternal externalizing behaviors were indirectly associated with the offspring\u27s externalizing behaviors through the offspring\u27s substance use in adolescence, the offspring\u27s partner\u27s smoking patterns, and the offspring\u27s marital conflict. Second, maternal cigarette smoking was indirectly associated with the offspring\u27s externalizing behaviors through the offspring\u27s substance use in adolescence, the offspring\u27s partner\u27s cigarette smoking, and the offspring\u27s marital conflict. Third, maternal marital conflict had an indirect effect on the offspring\u27s externalizing behaviors, mediated by offspring marital conflict. Conclusions: The finding that externalizing behaviors can be transmitted from parent to child informs the need for family-based interventions that are appropriate to adolescents

Paraunitary oversampled filter bank design for channel coding

Oversampled filter banks (OSFBs) have been considered for channel coding, since their redundancy can be utilised to permit the detection and correction of channel errors. In this paper, we propose an OSFB-based channel coder for a correlated additive Gaussian noise channel, of which the noise covariance matrix is assumed to be known. Based on a suitable factorisation of this matrix, we develop a design for the decoder's synthesis filter bank in order to minimise the noise power in the decoded signal, subject to admitting perfect reconstruction through paraunitarity of the filter bank. We demonstrate that this approach can lead to a significant reduction of the noise interference by exploiting both the correlation of the channel and the redundancy of the filter banks. Simulation results providing some insight into these mechanisms are provided

Signal compaction using polynomial EVD for spherical array processing with applications

Multi-channel signals captured by spatially separated sensors often contain a high level of data redundancy. A compact signal representation enables more efficient storage and processing, which has been exploited for data compression, noise reduction, and speech and image coding. This paper focuses on the compact representation of speech signals acquired by spherical microphone arrays. A polynomial matrix eigenvalue decomposition (PEVD) can spatially decorrelate signals over a range of time lags and is known to achieve optimum multi-channel data compaction. However, the complexity of PEVD algorithms scales at best cubically with the number of channel signals, e.g., the number of microphones comprised in a spherical array used for processing. In contrast, the spherical harmonic transform (SHT) provides a compact spatial representation of the 3-dimensional sound field measured by spherical microphone arrays, referred to as eigenbeam signals, at a cost that rises only quadratically with the number of microphones. Yet, the SHT’s spatially orthogonal basis functions cannot completely decorrelate sound field components over a range of time lags. In this work, we propose to exploit the compact representation offered by the SHT to reduce the number of channels used for subsequent PEVD processing. In the proposed framework for signal representation, we show that the diagonality factor improves by up to 7 dB over the microphone signal representation with a significantly lower computation cost. Moreover, when applying this framework to speech enhancement and source separation, the proposed method improves metrics known as short-time objective intelligibility (STOI) and source-to-distortion ratio (SDR) by up to 0.2 and 20 dB, respectively

Adolescent Health Series - alcohol, tobacco, and other drug use among adolescents in sub-Saharan Africa : A narrative review

Abstract: Alcohol, tobacco, and other drug (ATOD) use by adolescents are major contributors to death and disability in sub-Saharan Africa (SSA). This paper reviews the extent of adolescents’ ATOD use, risk and protective factors, and studies evaluating prevention interventions for adolescents in SSA. It also describes the harms associated with adolescents’ ATOD use in SSA, which mainly include interpersonal violence, sexual risk behaviours, and negative academic outcomes. We use the socio-ecological model as our framework for understanding ATOD use risk and protective factors at individual, interpersonal, peer/school, and societal/structural levels. We used two strategies to find literature evaluating ATOD interventions for adolescents in SSA: (a) we sought systematic reviews of adolescent ATOD interventions in SSA covering the period 2000–2020; and (b) we used a comprehensive evidence review strategy and searched for studies that had evaluated ATOD interventions in all SSA countries between 2000 and 2020. Only two community interventions (a brief intervention and an HIV prevention intervention), out of four that were identified, were partially effective in reducing adolescent ATOD. Furthermore, only one school-based intervention (HealthWise), out of the six that we uncovered, had any effect on ATOD use among adolescents. Possible reasons why many interventions were not effective include methodological limitations, involvement of non-evidence- based education-only approaches in some studies, and shortcomings in adaptations of evidence-based interventions. The scale of ATOD and related problems is disproportionate to the number of evaluated interventions to address them in SSA. More ATOD interventions need to be developed and evaluated in well-powered and well-designed studies

Electric transport properties of single-walled carbon nanotubes functionalized by plasma ion irradiation method

科研費報告書収録論文(課題番号:13852016/研究代表者:畠山力三/プラズマイオン照射による新機能性進化ナノチューブ創製法の開発