Three-fermion problems in optical lattices

We present exact results for the spectra of three fermionic atoms in a single well of an optical lattice. For the three lowest hyperfine states of Li6 atoms, we find a Borromean state across the region of the distinct pairwise Feshbach resonances. For K40 atoms, nearby Feshbach resonances are known for two of the pairs, and a bound three-body state develops towards the positive scattering-length side. In addition, we study the sensitivity of our results to atomic details. The predicted few-body phenomena can be realized in optical lattices in the limit of low tunneling.Comment: 4 pages, 4 figures, minor changes, to appear in Phys. Rev. Let

Extracting Scattering Phase-Shifts in Higher Partial-Waves from Lattice QCD Calculations

L\"uscher's method is routinely used to determine meson-meson, meson-baryon and baryon-baryon s-wave scattering amplitudes below inelastic thresholds from Lattice QCD calculations - presently at unphysical light-quark masses. In this work we review the formalism and develop the requisite expressions to extract phase-shifts describing meson-meson scattering in partial-waves with angular-momentum l<=6 and l=9. The implications of the underlying cubic symmetry, and strategies for extracting the phase-shifts from Lattice QCD calculations, are presented, along with a discussion of the signal-to-noise problem that afflicts the higher partial-waves.Comment: 79 pages, 41 figure

Quantile mechanics II: changes of variables in Monte Carlo methods and GPU-optimised normal quantiles

With financial modelling requiring a better understanding of model risk, it is helpful to be able to vary assumptions about underlying probability distributions in an efficient manner, preferably without the noise induced by resampling distributions managed by Monte Carlo methods. This paper presents differential equations and solution methods for the functions of the form Q(x) = F −1(G(x)), where F and G are cumulative distribution functions. Such functions allow the direct recycling of Monte Carlo samples from one distribution into samples from another. The method may be developed analytically for certain special cases, and illuminate the idea that it is a more precise form of the traditional Cornish–Fisher expansion. In this manner the model risk of distributional risk may be assessed free of the Monte Carlo noise associated with resampling. The method may also be regarded as providing both analytical and numerical bases for doing more precise Cornish–Fisher transformations. Examples are given of equations for converting normal samples to Student t, and converting exponential to normal. In the case of the normal distribution, the change of variables employed allows the sampling to take place to good accuracy based on a single rational approximation over a very wide range of sample space. The avoidance of branching statements is of use in optimal graphics processing unit (GPU) computations as it avoids the effect of branch divergence. We give a branch-free normal quantile that offers performance improvements in a GPU environment while retaining the best precision characteristics of well-known methods. We also offer models with low probability branch divergence. Comparisons of new and existing forms are made on Nvidia GeForce GTX Titan and Tesla C2050 GPUs. We argue that in both single- and double-precisions, the change-of-variables approach offers the most GPU-optimal Gaussian quantile yet, working faster than the Cuda 5.5 built-in function

Energy harvesting-based spectrum access with incremental cooperation, relay selection and hardware noises

In this paper, we propose an energy harvesting (EH)-based spectrum access model in cognitive radio (CR) network. In the proposed scheme, one of available secondary transmitters (STs) helps a primary transmitter (PT) forward primary signals to a primary receiver (PR). Via the cooperation, the selected ST finds opportunities to access licensed bands to transmit secondary signals to its intended secondary receiver (SR). Secondary users are assumed to be mobile, hence, optimization of energy consumption for these users is interested. The EH STs have to harvest energy from the PT's radio-frequency (RF) signals to serve the PTPR communication as well as to transmit their signals. The proposed scheme employs incremental relaying technique in which the PR only requires the assistance from the STs when the transmission between PT and PR is not successful. Moreover, we also investigate impact of hardware impairments on performance of the primary and secondary networks. For performance evaluation, we derive exact and lower-bound expressions of outage probability (OP) over Rayleigh fading channel. Monte-Carlo simulations are performed to verify the theoretical results. The results present that the outage performance of both networks can be enhanced by increasing the number of the ST-SR pairs. In addition, the outage performance of both primary and secondary networks is severely degraded with the increasing of hardware impairment level. It is also shown that fraction of time used for EH and positions of the secondary users significantly impact on the system performance.Web of Science26125024

Multi-Pion States in Lattice QCD and the Charged-Pion Condensate

The ground-state energies of systems containing up to twelve $\pi^+$'s in a spatial volume V ~ (2.5 fm)^3 are computed in dynamical, mixed-action lattice QCD at a lattice spacing of ~ 0.125 fm for four different values of the light quark masses. Clean signals are seen for each ground state, allowing for a precise extraction of both the $\pi^+\pi^+$ scattering length and $\pi^+\pi^+\pi^+$-interaction from a correlated analysis of systems containing different numbers of $\pi^+$'s. This extraction of the $\pi^+\pi^+$ scattering length is consistent with than that from the $\pi^+\pi^+$-system alone. The large number of systems studied here significantly strengthens the arguments presented in our earlier work and unambiguously demonstrates the presence of a low energy $\pi^+\pi^+\pi^+$-interaction. The equation of state of a $\pi^+$ gas is investigated using our numerical results and the density dependence of the isospin chemical potential for these systems agrees well with the theoretical expectations of leading order chiral perturbation theory. The chemical potential is found to receive a substantial contribution from the $\pi^+\pi^+\pi^+$-interaction at the lighter pion masses. An important technical aspect of this work is the demonstration of the necessity of performing propagator contractions in greater than double precision to extract the correct results.Comment: 38 pages, 20 figure

Effect of spent coffee grounds and liquid worm fertilizer on the growth and yield of Brassica campestris L.

Brassica campestris L. plants are widely grown, including in Asian countries where the leaves are used to prepare Chinese sour pickled mustard greens. The potential benefits of the application of organic by-products and organic fertilizers in sustainable agricultural production have been shown in previous studies. Consequently, this study investigated the effectiveness of liquid worm fertilizer (LWF) and spent coffee grounds (SCG) individually and in combination on the growth of B. campestris. The results showed that LWF at the highest dose had positive effects on the growth and yield of B. campestris, but SGC had inhibitory effects. The treatment consisting of composted SCG + triple of the standard dose of LWF resulted in the best plot yield with 3,866.7 g.plot-1, followed by the treatment of fresh SCG + triple of the standard dose of LWF, which produced a yield of 3,766.7 g.plot-1. The lowest yield (2,100.0 g.plot-1) was observed in the treatment of 1 kg.m-2 fresh SCG + no LWF. The interaction effect between SCG and LWF on the plot yield of B. campestris L. was significant (F(4,18) = 4.6; p = 0.01) demonstrating enhanced yield when both SCG and LWF were used in combination

Introducing an agricultural app to rice farmers: A pilot study in Can Tho, Vietnam

Plantix is an agricultural app developed by a private company based in Germany which offers a diagnosis and advice for more than 30 crops. It has great potential as a new form of extension service complementing a traditional face-to-face extension service. The CGIAR Plant Health Initiative seeks to introduce the app as part of a package of innovations available for integrated pest and disease management to facilitate behavioral change among farmers. Plantix has been widely used in India but has not yet become very common in Vietnam. The aim of this pilot study was to test the usability of Plantix app for progressive rural rice growers in Vinh Thanh District, Can Tho City, Vietnam. A group of 15 farmers (5 woman and 11 men) participated in the training on use of the app and provided feedback after a two-week trial. The results show that the farmers seem to have some trust issues with the app’s diagnosis, as it reportedly failed to identify or distinguish early signs of certain pests and diseases on young rice. Nevertheless, the farmers showed interest in using Plantix app and considered it a useful tool once its early detection capacity is improved. The participants were experienced large-scaled rice farmers who were already quite familiar with the symptoms of regular pests and diseases. They agreed with the knowledge provided by Plantix. The farmers appeared to be conscious of the recommended dosage of chemical pesticides as written on product labels, however, the current local practice still involves overusing. This suggests that additional measures might be needed along with the introduction and dissemination of Plantix for a stronger impact on farmers’ behaviors. The app can be very useful for farmers when they start growing new crops, when there are new pests and diseases, and when they have difficulties distinguishing one disease from others with similar symptoms. Some of the farmers suggested the need for information about new generation pesticides. They also expressed the need for recommendations of specific “top-ranked” pesticide products, to help them navigate the large number of products and brands currently on the market. Considering the gender division of labor and decision-making, the results show that men are usually responsible for pest and disease management, but women are also involved in decision-making to some extent. It will be interesting to observe how women’s improved knowledge on pest and disease management obtained through Plantix will lead to change in household decisions on pesticide use. The participating farmers use various sources such as TV, Internet, extension workers, input suppliers and peer farmers as means of accessing information and exchanging knowledge. Male farmers tend to learn new agricultural technologies through social networks within their villages and the Internet more often, while the women do that through the Internet and TV. However, both groups trusted their own experience the most. Therefore, introducing the community’s key farmers to new technologies though demonstration and success stories could work as a strategy to ignite behavior change among peer farmers. In addition, communication via the Internet and TV could quickly reach a large number of farmers. Involving input suppliers and extension workers in the introduction of the Plantix app could also be helpful. While this pilot study focused on large-scaled farmers, there are smallholder farmers from poor households in some remote areas in the Mekong Delta. Their needs and knowledge may be significantly different from those of progressive farmers. Introducing the app to different types of farmers can help us understand the diverse needs and priorities of farmers in the process of digitalization

Energy Harvesting-based Spectrum Access with Incremental Cooperation, Relay Selection and Hardware Noises

In this paper, we propose an energy harvesting (EH)-based spectrum access model in cognitive radio (CR) network. In the proposed scheme, one of available secondary transmitters (STs) helps a primary transmitter (PT) forward primary signals to a primary receiver (PR). Via the cooperation, the selected ST finds opportunities to access licensed bands to transmit secondary signals to its intended secondary receiver (SR). Secondary users are assumed to be mobile, hence, optimization of energy consumption for these users is interested. The EH STs have to harvest energy from the PT's radio-frequency (RF) signals to serve the PT-PR communication as well as to transmit their signals. The proposed scheme employs incremental relaying technique in which the PR only requires the assistance from the STs when the transmission between PT and PR is not successful. Moreover, we also investigate impact of hardware impairments on performance of the primary and secondary networks. For performance evaluation, we derive exact and lower-bound expressions of outage probability (OP) over Rayleigh fading channel. Monte-Carlo simulations are performed to verify the theoretical results. The results present that the outage performance of both networks can be enhanced by increasing the number of the ST-SR pairs. In addition, it is also shown that fraction of time used for EH, positions of the secondary users and the hardware-impairment level significantly impact on the system performance

Autophagy Inhibitor Chloroquine Downmodulates Hepatic Stellate Cell Activation and Liver Damage in Bile-Duct-Ligated Mice

Hepatic stellate cell (HSC) activation via the autophagy pathway is a critical factor in liver fibrogenesis. This study tests the hypothesis that chloroquine (CQ) treatment can prevent autophagy and HSC activation in vitro and in vivo in bile-duct-ligated (BDL) mice. Sham-operated and BDL mice were treated with either PBS or CQ in two 60 mg/kg doses the day (D) before and after surgery. On day 2 (2D), HSCs were isolated, and their biological activities were evaluated by measuring intracellular lipid content, alpha-sma/collagen, and expression of autophagy lc3, sqstm1/p62 markers. The treatment efficacy on liver function was evaluated with serum albumin, transaminases (AST/ALT), and hepatic histology. Primary HSCs were treated in vitro for 24 h with CQ at 0, 2.5, 5, 10, 30, and 50 mu M. Autophagy and HSC activation were assessed after 2D of treatment. CQ treatment improved serum AST/ALT, albumin, and bile duct proliferation in 2D BDL mice. This is associated with a suppression of HSC activation, shown by higher HSC lipid content and collagen I staining, along with the blockage of HSC autophagy indicated by an increase in p62 level and reduction in lc3 staining. CQ 5 mu M inhibited autophagy in primary HSCs in vitro by increasing p62 and lc3 accumulation, thereby suppressing their in vitro activation. The autophagy inhibitor CQ reduced HSC activation in vitro and in vivo. CQ improved liver function and reduced liver injury in BDL mice