Background Fungal stem end rot disease of pitaya caused by Alternaria alternata is one of the most destructive diseases in Binh Thuan province, Vietnam. This study aimed to assess the antagonistic effects of some endophytic bacteria isolated from the weed plant (Echinochloa colonum) against A. alternata. Results A total of 19 endophytic bacteria were isolated and 5 of them presented in vitro antagonistic activity against A. alternata. Of five, strain EC80 significantly inhibited the pathogenic growth with a mean inhibition diameter of 11.88 ± 0.08 mm, while the other four (C79, EC83, EC90, and EC97) showed a weak inhibition. Interestingly, the combination of EC79 and EC80 reduced more biomass of pathogenic fungi than the single one did. EC79 showed positive results for amylase, indole acetic acid (IAA), and biofilm production, whereas EC80 presented positive capabilities for IAA and biofilm production and a negative one for amylase production. In addition, the combined filtrate of EC79 and EC80 presented non-antifungal activity on biocontrol tests in vitro, indicating that bacteria cells played a role in defending against the pathogen. Moreover, both isolates EC79 and EC80 significantly increased seedling biomass than the control. Conclusions The results suggest that those two strains in combination had the potential to be used as a biocontrol agent against A. alternata. More studies should be done in the future to evaluate their efficiency under the field conditions.

We analyse the performance of an incentive scheme for two-hop DTNs in which a backlogged source proposes a xed reward to the relays to deliver a message. Only one message at a time is proposed by the source. For a given message, only the rst relay to deliver it gets the reward corresponding to this message thereby inducing a competition between the relays. The relays seek to maximize the expected reward for each message whereas the objective of the source is to satisfy a given constraint on the probability of message delivery. We show that the optimal policy of a relay is of threshold type: it accepts a message until a rst threshold and then keeps the message until it either meets the destination or reaches the second threshold. Formulas for computing the thresholds as well as probability of message delivery are derived for a backlogged source.

Reading habits and writing performance reportedly share a close correlation; however, there has been less investigation on this aspect in Vietnam. The research aims to bridge the gap in the literature review with a description of Van Lang University English majors’ reading patterns, a report of their writing ability, and a conclusion on the relation between these two elements. Quantitative data were collected through an online questionnaire discovering students’ reading habits and a writing test administered to evaluate their writing performance. The test results were analyzed through Statistical Package for the Social Sciences 26 (SPSS 26). Additionally, Pearson correlation and linear regression were applied to confirm the influences of five elements in reading habits on students’ writing performance. Qualitative data were obtained through a structured interview and then quantified with Microsoft Excel 2019. The interview was carried out to generalize the reading patterns of different purposive samples categorized by their writing marks. The result of the study asserts a positive correlation between students’ reading habits and their writing performance (robtained=0.433 to 0.542), and nearly 60% of the segments of the reading patterns were proved to have a great contribution to writing ability. The study indicates that a good reading habit entails improvement in writing achievement. The research suggests further investigation of factors influencing reading habits, the effects of teachers' instructions on students' writing performance, and the genres of essays that are most affected by reading patterns.

Advanced persistent threats (APTs) are stealthy attacks which make use of social engineering and deception to give adversaries insider access to networked systems. Against APTs, active defense technologies aim to create and exploit information asymmetry for defenders. In this paper, we study a scenario in which a powerful defender uses honeynets for active defense in order to observe an attacker who has penetrated the network. Rather than immediately eject the attacker, the defender may elect to gather information. We introduce an undiscounted, infinite-horizon Markov decision process on a continuous state space in order to model the defender's problem. We find a threshold of information that the defender should gather about the attacker before ejecting him. Then we study the robustness of this policy using a Stackelberg game. Finally, we simulate the policy for a conceptual network. Our results provide a quantitative foundation for studying optimal timing for attacker engagement in network defense.