Free-Rider Games for Cooperative Spectrum Sensing and Access in CIoT Networks.

With the rapid development of technologies such as wireless communications and the Internet of Things (IoT), the proliferation of IoT devices will intensify the competition for spectrum resources. The introduction of cognitive radio technology in IoT can minimize the shortage of spectrum resources. However, the open environment of cognitive IoT may involve free-riding problems. Due to the selfishness of the participants, there are usually a large number of free-riders in the system who opportunistically gain more rewards by stealing the spectrum sensing results from other participants and accessing the spectrum without spectrum sensing. However, this behavior seriously affects the fault tolerance of the system and the motivation of the participants, resulting in degrading the system's performance. Based on the energy-harvesting cognitive IoT model, this paper considers the free-riding problem of Secondary Users (SUs). Since free-riders can harvest more energy in spectrum sensing time slots, the application of energy harvesting technology will exacerbate the free-riding behavior of selfish SUs in Cooperative Spectrum Sensing (CSS). In order to prevent the low detection performance of the system due to the free-riding behavior of too many SUs, a penalty mechanism is established to stimulate SUs to sense the spectrum normally during the sensing process. In the system model with multiple primary users (PUs) and multiple SUs, each SU considers whether to free-ride and which PU's spectrum to sense and access in order to maximize its own interests. To address this issue, a two-layer game-based cooperative spectrum sensing and access method is proposed to improve spectrum utilization. Simulation results show that compared with traditional methods, the average throughput of the proposed TL-CSAG algorithm increased by 26.3% and the proposed method makes the SUs allocation more fair.

Effects of Harvest Maturity on the Fruit Quality of Different Flesh-Type Peach Stored at Near-Freezing Point Temperature.

To investigate the peach fruit flesh types (soft-melting, hard-melting, stonyhard and non-melting) and harvest maturity level suitable for near-freezing temperature storage (NFTS), eight peach cultivars that had four flesh types were used as test materials. Changes in fruit respiration intensity and ethylene release rates, as well as the differences in quality indexes, such as soluble solids content (SSC), firmness, color difference, pigment content, soluble sugar and organic acid component content, of three fruit maturity levels (70%, 80% and 90% maturity) under NFTS conditions were analyzed and compared. The fruit quality indexes of peach having different maturity levels and flesh types changed little during NFTS. The SSC and total sugar content of hard-melting and stonyhard peach fruit were higher than those of other flesh types during NFTS. Those fruit maintained greater firmness at the end of the storage period. The differences in respiration intensity and ethylene release rate were small, but for fruit coloring, hard-melting fruit performed better than stonyhard fruit. The 80%, compared with the 90%, maturity stage maintained more fruit moisture, had less fruit mass loss and maintained a greater edible firmness. It effectively impeded the fruit senescence process and was the most suitable maturity for NFTS. Thus, the hard-melting peach maintained the highest commercial value and desirable storage characteristics under NFTS conditions, and its 80% maturity level was the most suitable for NFTS.

Bioinformatics prediction of miRNAs in the Prunus persica genome with validation of their precise sequences by miR-RACE.

We predicted 262 potential MicroRNAs (miRNAs) belonging to 70 miRNA families from the peach (Prunus persica) genome and two specific 5' and 3' miRNA rapid amplification of cDNA ends (miR-RACE) PCR reactions and sequence-directed cloning were employed to accurately validate 61 unique P. persica miRNAs (Ppe-miRNAs) sequences belonging to 61 families comprising 97 Ppe-miRNAs. Validation of the termini nucleotides in particular can define the real sequences of the Ppe-miRNAs on peach genome. Comparison between predicted and validated Ppe-miRNAs through alignment revealed that 43 unique orthologous sequences were identical, while the remaining 18 exhibited some divergences at their termini nucleotides. Quantitative real-time polymerase chain reaction (qRT-PCR) was further employed to analyze the expression of all the 61 miRNAs and 10 putative targets of 8 randomly selected Ppe-miRNAs in peach leaves, flowers and fruits at different stages of development, where both the miRNAs and the putative target genes showed tissue-specific expression.

[Photosynthesis of five magnolia species in Nanjing City in winter and spring].

The photosynthesis and fluorescence characteristics of five magnolia ornamental species naturally distributed in various subtropical areas were studied in Nanjing City in winter and spring. The results showed that the diurnal changes of net photosynthetic rate (P(n)) and water use efficiency (WUE) of test species in winter were different from those in spring. The diurnal integral values of P(n), apparent quantum yield (AQY) and carboxylation efficiency (CE) were lower in winter than in spring, and the F(o) was higher, while the F(v)/F(m) F(v)/F(o) phi PS II, F(v)'/F(m)', ETR, qP and NPQ were lower in winter than in spring. The differences among the five species were remarkable, among which, Parakmeria lotungensis and Michelia platypetala mainly distributed in middle-subtropical area had higher diurnal integral values of P(n), AQY, CE and LSP, but lower value of LCP than other species in winter and spring. Their F(v)/F(m), F(v)/F(o),phi PS II, F(v)'/F(m)', ETR, qP and NPQ were also higher, indicating that they had higher photosynthetic capacity and wider ecological ranges of light adaptability. Manglietia insignis and Michelia wilsonii mainly distributed in southern subtropical area had lower photosynthetic capacity, and their fluorescence parameters were also lower in winter. Grey correlation analysis showed the main factors affecting the P(n) of test magnolia species in winter were T(a) and PAR.

[Photosynthetic characteristics of grapevine varieties with different ecological adaptabilities grown in a rain-shelter plastic greenhouse in the Yangtze River Delta region].

The study with two grapevine varieties Manicure Finger and Fujiminori grown in a rain-shelter plastic greenhouse in the Yangtze River Delta region showed that in the greenhouse, the photon flux density (PFD) decreased greatly, while air temperature (Ta), vapor pressure (Vp) and transpiration rate (Tr) had little changes, no matter in sunny or cloudy days. The leaf thickness and fresh weight per cm2 of the two varieties decreased by 28.6% and 18.4%, and 13.1% and 11.6%, respectively, total chlorophyll content and apparent quantum yield (AQY) had a slight increase, but chlorophyll a and b contents and chlorophyll a/b ratio had no obvious difference with the open-air cultivation (CK). In sunny days, the diurnal mean value of net photosynthetic rate Pn, diurnal integral value of Pn, and water use efficiency (WUE) of Manicure Finger and Fujiminori decreased by 18.7% and 13.1%, 17.2% and 11.9%, and 26.0% and 36.9%, but stomatal conductance (Gs) increased by 76.8% and 100.8%, respectively, while in cloudy days, the corresponding values of above-mentioned parameters were decreased by 48.7% and 33.5%, 34.0% and 29.8%, and 69.2% and 67.7%, and increased by 178.0% and 85.1%, respectively. The variation extents of the parameters were larger for Manicure Finger than for Fujiminori, especially in cloudy days, indicating the great differences of ecological adaptability between these two grapevine varieties.