A Comment on "Memory Effects in an Interacting Magnetic Nanoparticle System"

Recently, Sun et al reported that striking memory effects had been clearly observed in their new experiments on an interacting nanoparticle system [1]. They claimed that the phenomena evidenced the existence of a spin-glass-like phase and supported the hierarchical model. No doubt that a particle system may display spin-glass-like behaviors [2]. However, in our opinion, the experiments in Ref. [1] cannot evidence the existence of spin-glass-like phase at all. We will demonstrate below that all the phenomena in Ref. [1] can be observed in a non-interacting particle system with a size distribution. Numerical simulations of our experiments also display the same features.Comment: A comment on "Phys. Rev. Lett. 91, 167206

A CENTER OF A POLYTOPE: AN EXPOSITORY REVIEW AND A PARALLEL IMPLEMENTATION

ABSTRACT. The solution space of the rectangular linear system Az b, subject to x> 0, is called a polytope. An attempt is made to provide a deeper geometric insight, with numerical examples, into the condensed paper by Lord, et al. [1], that presents an algorithm to compute a center of a polytope. The algorithm is readily adopted for either sequential or parallel computer implementation. The computed center provides an initial feasible solution (interior point) of a linear programming problem. KEY WORDS AND PHRASES. Center of a polytope, consistency check, Euclidean distance, initial feasible solution, linear programming, Moore-Penrose inverse, nonnegative solution

Eco-holobiont : a new concept to identify drivers of host-associated microorganisms

Host microbiomes play a critical role in host fitness and health. Whilst the current 'holobiont' concept framework has greatly expanded eco-evolutionary and functional understanding of host-microbiome interactions, the important role of biotic interactions and microbial loop (compositional linkage between soil, plant and animal) in shaping host-microbiome are poorly understood. We proposed an 'eco-holobiont' concept to fill the knowledge gap

Spontaneous excitation of an accelerated multilevel atom in dipole coupling to the derivative of a scalar field

We study the spontaneous excitation of an accelerated multilevel atom in dipole coupling to the derivative of a massless quantum scalar field and separately calculate the contributions of the vacuum fluctuation and radiation reaction to the rate of change of the mean atomic energy of the atom. It is found that, in contrast to the case where a monopole like interaction between the atom and the field is assumed, there appear extra corrections proportional to the acceleration squared, in addition to corrections which can be viewed as a result of an ambient thermal bath at the Unruh temperature, as compared with the inertial case, and the acceleration induced correction terms show anisotropy with the contribution from longitudinal polarization being four times that from the transverse polarization for isotropically polarized accelerated atoms. Our results suggest that the effect of acceleration on the rate of change of the mean atomic energy is dependent not only on the quantum field to which the atom is coupled, but also on the type of the interaction even if the same quantum scalar field is considered.Comment: 11 pages, no figure

Numerical Simulation of Sub-cooled Boiling Flow with Fouling Deposited inside Channels

This document is the Accepted Manuscript version of the following article: X. Liu, X. Zhang, T. Lu, K. Mahkamov, H. Wu, and M. Mirzaeian 'Numerical simulation of sub-cooled boiling flow with fouling deposited inside channels', Applied Thermal Engineering, Vol. 203, pp. 434-442, June 2016. The version of record is available online at doi: https://doi.org/10.1016/j.applthermaleng.2016.04.041. © 2016 Elsevier Ltd. All rights reserved.In this article, a numerical simulation has been performed to investigate the sub-cooled boiling flow in axisymmetric channels using the two-phase particle model. The equivalent diameter of the channel is 4.38 mm with 365.7 cm in length. The fouling deposited layer is filled with subsequent two-thirds of the flow channel. The internal surface of the channel is covered by a fouling deposit layer with a thickness ranging from 0.225 mm to 1.55 mm. Uniform heat flux of 29267.6 W/m2 is applied on the heated wall. Validation of the CFD model is carried out through comparison with open published experimental data and a close agreement is achieved. A new parameter, Security factor, is introduced and defined in the current study. Numerical results show that the developed two-phase particle model could well predict the water-steam two-phase change flow. The Nusselt number in the fouling region without fouling deposited could be 50 times higher than that with fouling layer. The heat transfer performance of the channel with thickness of 0.225 mm fouling deposit layer is 5 times larger than that with thickness of 1.55 mm fouling deposit layer. It is also found that the inlet velocity has significant impact on the boiling and total pressure drops along the channel.Peer reviewe

Ethical leadership and follower voice and performance: the role of follower identifications and entity morality beliefs

Previous studies have investigated a number of psychological mechanisms that mediate the relationships between ethical leaderships and follower outcomes. Follower organizational identification has been found to mediate the relationship between ethical leadership and follower job performance. In this research, we incorporate a second distinct and theoretically important type of social identification process, relational identification with the leader, and examine their mediating effects on follower performance and voice outcomes. Further, we bring the implicit theory of morality to the behavioral ethics literature and examine follower morality beliefs as a moderator. Using a Romanian sample, we found that ethical leadership has an indirect effect on follower job performance and voice (through the mediating mechanisms of both organizational and relational identifications) and that these relationships are stronger for followers who held the implicit theory that a person’s moral character is fixed. Theoretical and practical implications are discussed

G\"odel-type universes in f(T) gravity

The issue of causality in $f(T)$ gravity is investigated by examining the possibility of existence of the closed timelike curves in the G\"{o}del-type metric. By assuming a perfect fluid as the matter source, we find that the fluid must have an equation of state parameter greater than minus one in order to allow the G\"{o}del solutions to exist, and furthermore the critical radius $r_c$, beyond which the causality is broken down, is finite and it depends on both matter and gravity. Remarkably, for certain $f(T)$ models, the perfect fluid that allows the G\"{o}del-type solutions can even be normal matter, such as pressureless matter or radiation. However, if the matter source is a special scalar field rather than a perfect fluid, then $r_c\rightarrow\infty$ and the causality violation is thus avoided.Comment: 18 pages, introduction revised, reference adde

Simultaneous utilization of glucose and xylose for lipid production by Trichosporon cutaneum

<p>Abstract</p> <p>Background</p> <p>Biochemical conversion of lignocellulose hydrolysates remains challenging, largely because most microbial processes have markedly reduced efficiency in the presence of both hexoses and pentoses. Thus, identification of microorganisms capable of efficient and simultaneous utilization of both glucose and xylose is pivotal to improving this process.</p> <p>Results</p> <p>In this study, we found that the oleaginous yeast strain <it>Trichosporon cutaneum </it>AS 2.571 assimilated glucose and xylose simultaneously, and accumulated intracellular lipid up to 59 wt% with a lipid coefficient up to 0.17 g/g sugar, upon cultivation on a 2:1 glucose/xylose mixture in a 3-liter stirred-tank bioreactor. In addition, no classic pattern of diauxic growth behavior was seen; the microbial cell mass increased during the whole culture process without any lag periods. In shake-flask cultures with different initial glucose:xylose ratios, glucose and xylose were consumed simultaneously at rates roughly proportional to their individual concentrations in the medium, leading to complete utilization of both sugars at the same time. Simultaneous utilization of glucose and xylose was also seen during fermentation of corn-stover hydrolysate with a lipid content and coefficient of 39.2% and 0.15 g/g sugar, respectively. The lipid produced had a fatty-acid compositional profile similar to those of conventional vegetable oil, indicating that it could have potential as a raw material for biodiesel production.</p> <p>Conclusion</p> <p>Efficient lipid production with simultaneous consumption of glucose and xylose was achieved in this study. This process provides an exciting opportunity to transform lignocellulosic materials into biofuel molecules, and should also encourage further study to elucidate this unique sugar-assimilation mechanism.</p

A Two-level Prediction Model for Deep Reactive Ion Etch (DRIE)

We contribute a quantitative and systematic model to capture etch non-uniformity in deep reactive ion etch of microelectromechanical systems (MEMS) devices. Deep reactive ion etch is commonly used in MEMS fabrication where high-aspect ratio features are to be produced in silicon. It is typical for many supposedly identical devices, perhaps of diameter 10 mm, to be etched simultaneously into one silicon wafer of diameter 150 mm. Etch non-uniformity depends on uneven distributions of ion and neutral species at the wafer level, and on local consumption of those species at the device, or die, level. An ion–neutral synergism model is constructed from data obtained from etching several layouts of differing pattern opening densities. Such a model is used to predict wafer-level variation with an r.m.s. error below 3%. This model is combined with a die-level model, which we have reported previously, on a MEMS layout. The two-level model is shown to enable prediction of both within-die and wafer-scale etch rate variation for arbitrary wafer loadings.Singapore-MIT Alliance (SMA

Sustainable agricultural practices contribute significantly to One Health

The One Health concept proposes that the health of humans, animals, and the environment are interconnected. Agricultural production is a critical component of One Health as food links the environment to human health. Food not only provides nutrients to humans but also represents an important pathway for human exposure to environmental microbes as well as potentially harmful agrochemicals. In addition, inappropriate agronomic practices can cause damage to the environment which can have unintended adverse impacts on human health. Therefore, improving agricultural production systems and protecting environmental health should not be viewed as isolated goals as they are strongly interlinked. Here, we used the nexus of soil, plant, and human microbiomes to discuss sustainable agricultural production from the One Health perspective. We highlighted three interconnected challenges faced by current agronomic practices: the transmissions of pathogens in soil‐human microbial loops, the dissemination of antibiotic resistance genes in agroecosystems, and the impacts of chemical pesticides on humans and environmental health. Finally, we propose the potential of utilising microbiomes for better sustainable agronomic practices to contribute to key goals of the One Health concept