A Multiplicative Seasonal ARIMA/GARCH Model in EVN Traffic Prediction

This paper highlights the statistical procedure used in developing models that have the ability of capturing and forecasting the traffic of mobile communication network operating in Vietnam. To build such models, we follow Box-Jenkins method to construct a multiplicative seasonal ARIMA model to represent the mean component using the past values of traffic, then incorporate a GARCH model to represent its volatility. The traffic is collected from EVN Telecom mobile communication network. Diagnostic tests and examination of forecast accuracy measures indicate that the multiplicative seasonal ARIMA/GARCH model, i.e. ARIMA (1, 0, 1) × (0, 1, 1)24/GARCH (1, 1) shows a good estimation when dealing with volatility clustering in the data series. This model can be considered to be a flexible model to capture well the characteristics of EVN traffic series and give reasonable forecasting results. Moreover, in such situations that the volatility is not necessary to be taken into account, i.e. short-term prediction, the multiplicative seasonal ARIMA/GARCH model still acts well with the GARCH parameters adjusted to GARCH (0, 0).

Alkoxy encapsulation of carbazole-based thermally activated delayed fluorescent dendrimers for highly efficient solution-processed organic light-emitting diodes

Two n-butoxy-encapsulated dendritic thermally activated delayed fluorescent(TADF) emitters(namely O-D1 and O-D2) with the first-/second-generation carbazoledendrons are designed and synthesized via C—N coupling between carbazoledendrons and 2,4,6-tris(4-bromophenyl)-1,3,5-triazine core.It is found that,compa red with the commo nly-used tert-butyl groups,the use of n-butoxy encapsulation groups can lead to smallersinglet-triplet energy gap for the dendrimers,producing stronger TADF effect together with faster reverse intersystem crossing process.Solution-processed TADF organic light-emitting diodes(OLEDs) utilizingalkoxy-encapsulated dendrimers O-D1 and O-D2 as emitters exhibitstate-of-the-art device efficiency withthe maximum external quantum efficiency up to 16.8% and 20.6%,respectively,which are ~1.6 and~2.0 times that of the tert-butyl-encapsulated counterparts.These results suggest that alkoxy encapsulation of the carbazole-based TADF dendrimers can be a promising approach for developing highly efficient emitters for solution-processed OLEDs.

Metabolomic profiles in a green alga (Raphidocelis subcapitata) following erythromycin treatment: ABC transporters and energy metabolism

A recent study showed that erythromycin(ERY)exposure caused hormesis in a model alga(Raphidocelis subcapitata)where the growth was promoted at an environmentally realistic concentration(4μg/L)but inhibited at two higher concentrations(80 and 120μg/L),associated with opposite actions of certain signaling pathways(e.g.,xenobiotic metabolism,DNA replication).However,these transcriptional alterations remain to be investigated and verified at the metabolomic level.This study uncovered metabolomic profiles and detailed toxic mechanisms of ERY in R.subcapitata using untargetedmetabolomics.Themetabolomic analysis showed that metabolomic pathways including ABC transporters,fatty acid biosynthesis and purine metabolism were associated with growth promotion in algae treated with 4μg/L ERY.An overcompensation was possibly activated by the low level of ERY in algae where more resources were reallocated to efficiently restore the temporary impairments,ultimately leading to the outperformance of growth.By contrast,algal growth inhibition in the 80 and 120μg/L ERY treatments was likely attributed to the dysfunction of metabolomic pathways related to ABC transporters,energy metabolism and metabolism of nucleosides.Apart from binding of ERY to the 50S subunit of ribosomes to inhibit protein translation as in bacteria,the data presented here indicate that inhibition of protein translation and growth performance of algae by ERY may also result from the suppression of amino acid biosynthesis and aminoacyl-tRNA biosynthesis.This study provides novel insights into the dose-dependent toxicity of ERY on R.subcapitata.