No abstract

In this paper, we study the security of a compressed sensing (CS) based cryptosystem called a sparse one-time sensing (S-OTS) cryptosystem, which encrypts a plaintext with a sparse measurement matrix. To construct the secret matrix and renew it at each encryption, a bipolar keystream and a random permutation pattern are employed as cryptographic primitives, which can be obtained by a keystream generator of stream ciphers. With a small number of nonzero elements in the measurement matrix, the S-OTS cryptosystem achieves efficient CS encryption in terms of memory and computational cost. In security analysis, we show that the S-OTS cryptosystem can be indistinguishable as long as each plaintext has constant energy, which formalizes computational security against ciphertext only attacks (COA). In addition, we consider a chosen plaintext attack (CPA) against the S-OTS cryptosystem, which consists of two sequential stages, keystream and key recovery attacks. Against keystream recovery under CPA, we demonstrate that the S-OTS cryptosystem can be secure with overwhelmingly high probability, as an adversary needs to distinguish a prohibitively large number of candidate keystreams. Finally, we conduct an information-theoretic analysis to show that the S-OTS cryptosystem can be resistant against key recovery under CPA by guaranteeing that the probability of success is extremely low. In conclusion, the S-OTS cryptosystem can be computationally secure against COA and the two-stage CPA, while providing efficiency in CS encryption.

This study aimed to identify the effects of oxidized brown coal humic acid fertilizer on the relative growth rate of several tree species intended for reforestation. Field experiments were carried out during 2011-2014 at the Research and Experimental Center for Combating Desertification located at the Elsen Tasarkhai station in central Mongolia. The trees studied were Populus sibirica Tausch., Salix ledebouriana Trautv., and Acer tataricum L. The experiment was conducted with concentrations of 2000, 10,000, and 20,000 mg L −1 of humic acid fertilization treatment. Measurement of the relative height growth rate (RHGR) was undertaken for a period of four years. The results demonstrated significant differences between the humic fertilizer concentrations, which varied depending on the species. Compared to monthly RHGR over the study period, the treatment using fertilizers yielded significantly better tree growth. P. sibirica, when treated with 2000 mg L −1 and 10,000 mg L −1 humic acid fertilizers, had significant height growth rates. S. ledebouriana with 20,000 mg L −1 of humic acid fertilzers treatments showed the highest RHGR. In addition, when the humic acid treatments were compared to the control, results showed that oxidized brown coal humic acid fertilizers as an organic fertilizer can have a significant effect on the growth of A. tataricum. The results equally showed that the soil chemical properties EC, CO 2 , NO 3 , and K 2 O were significant among all the treatments compared to control. The effect on P 2 O 5 significantly increased in all the treatments; however, there was no significant effect on pH and Mg among all treatments. Combining the results obtained with reforestation and sustainable land-management practices can help to improve soil organics in degraded sandy soil regions.

No abstract

No abstract

Aims This study sought to evaluate how soil organic carbon (SOC) and total nitrogen (STN) stocks vary following the conversion of a deciduous natural forest (DNF) to a paddy rice farm (PRF), a seventy-year-old Pinus koraiensis monoculture (CP70), a mixed forest (MF) plantation, and a P. koraiensis monoculture resulting from the re-plantation of a portion of the CP70 attacked by bugs. Methods Soil samples (0-30 cm) were collected from DNF, PRF, CP7, CP70 and MF in the Gwangneung experimental site located in Gyeonggi-do (South Korea), and analyzed for bulk density, pH, SOC, STN content and stocks (0-30 cm). Results The conversion of DNF into PRF showed 23.9% SOC stocks and 54.5% STN stocks increases. However, there were no significant changes in STN or SOC stocks after DNF was reforested for seven or 70 years or when PRF was reforested to MF. Conclusions The conversion of a DNF to a PRF increased the SOC and STN stock, which might be due to over 63 years' fertilizations with urea and diammonium phosphate, but reforestation with a P. koraiensis monoculture for 70 years and/or mixed forest was enough time to restore SOC and STN stocks to natural levels.

No abstract

The present work aimed to determine the phytoextraction potential of four poplar hybrids when treated with mixed heavy metals, cadmium (Cd), chromium, (Cr), copper (Cu), and zinc (Zn) under greenhouse conditions. Poplar hybrids were treated once with six different concentrations (0, 5, 50, 100, 200, and 500 mg L ¡1) of mixed heavy metals over a period of 3 months, after which the plants were harvested, dried, digested using the aqua regia method and the heavy metal concentrations in the roots, stem, and leaves were determined. Individual heavy metal analysis using ICP-AES of separate heavy metals in plant parts demonstrated higher Zn accumulation in leaves, compared to all other heavy metals. As for Cd, Cr, and Cu the concentration accumulation in the leaves, stem, and roots varied across hybrids. Based on the phytoextraction potential of the four hybrids, hybrid 1 (Eco 28) was determined as a suitable candidate for phytoextraction of multi-contaminated sites, with DN 034 also showing selective phytoextraction potential in the early stages of growth.