6,640 research outputs found
Emergence, Evolution and Scaling of Online Social Networks
This work was partially supported by AFOSR under Grant No. FA9550-10-1-0083, NSF under Grant No. CDI-1026710, NSF of China under Grants Nos. 61473060 and 11275003, and NBRPC under Grant No. 2010CB731403. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
Epiphyllous liverworts on rosette leaves of Ardisia species (Myrsinaceae) in China
Four species of Ardisia (Myrsinaceae, Magnoliopsida) with rosette or low-lying leaves in China (including Hong Kong) have been found to be the hosts for 12 species of epiphyllous liverworts which belong to 4 families and 9 genera. However, no obvious species-specific hostepiphyte relationship could be recognized
High Current Matching over Full-Swing and Low-Glitch Charge Pump Circuit for PLLs
A high current matching over full-swing and low-glitch charge pump (CP) circuit is proposed. The current of the CP is split into two identical branches having one-half the original current. The two branches are connected in source-coupled structure, and a two-stage amplifier is used to regulate the common-source voltage for the minimum current mismatch. The proposed CP is designed in TSMC 0.18µm CMOS technology with a power supply of 1.8 V. SpectreRF based simulation results show the mismatch between the current source and the current sink is less than 0.1% while the current is 40 µA and output swing is 1.32 V ranging from 0.2 V to 1.52 V. Moreover, the transient output current presents nearly no glitches. The simulation results verify the usage of the CP in PLLs with the maximum tuning range from the voltage-controlled oscillator, as well as the low power supply applications
RODENT CONTROL IN CHINA
Rodent pest problems and their control in China are reviewed. Three commensal species, Rattus norvegicus, R. flavipectus and Mus musculus, are important pests both in urban and rural regions. Mus musculus is the most widely distributed species in China. Its population density is cyclic, unique for a commensal species in being found in the arid Xinjiang (Sinkiang) Autonomous Region in Northwest China. In South China, R. losea and Bandicota indica are serious problems in rice and cane fields. Many different genera of field rodents are considered pests to agriculture and/or are reservoirs of rodent-borne diseases. These include Citellus, Marmota, Meriones, Cricetulus, Microtus, Apodemus, Ochotona, Myospalax, Clethrionomys, Sciurus, and Eutamias. The ecology and control of these rodents are included. There are a series of efficient administrative organizations responsible for rodent control. Most campaigns of commensal rodents have relied on a combination of rodenticides and different types of traps, but in the case of field rodents the reliance is heavily placed on poison baits. Diphacinone (Na-salt) is most frequently used for control of commensal species. Zinc phosphide, fluoroacetimide (1081), sodium fluoroacetate (1080), glyftor and 0.2% diphacinone (Na-salt) are used for field rodent control. Information is supplied on the susceptibility of important rodents in China to different rodenticides, including difenacoum and brodifacoum, and on other means of rodent control
CATTmew: Defeating Software-only Physical Kernel Isolation
All the state-of-the-art rowhammer attacks can break the MMU-enforced
inter-domain isolation because the physical memory owned by each domain is
adjacent to each other. To mitigate these attacks, physical domain isolation,
introduced by CATT, physically separates each domain by dividing the physical
memory into multiple partitions and keeping each partition occupied by only one
domain. CATT implemented physical kernel isolation as the first generic and
practical software-only defense to protect kernel from being rowhammered as
kernel is one of the most appealing targets.
In this paper, we develop a novel exploit that could effectively defeat the
physical kernel isolation and gain both root and kernel privileges. Our exploit
can work without exhausting the page cache or the system memory, or relying on
the information of the virtual-to-physical address mapping. The exploit is
motivated by our key observation that the modern OSes have double-owned kernel
buffers (e.g., video buffers and SCSI Generic buffers) owned concurrently by
the kernel and user domains. The existence of such buffers invalidates the
physical kernel isolation and makes the rowhammer-based attack possible again.
Existing conspicuous rowhammer attacks achieving the root/kernel privilege
escalation exhaust the page cache or even the whole system memory. Instead, we
propose a new technique, named memory ambush. It is able to place the
hammerable double-owned kernel buffers physically adjacent to the target
objects (e.g., page tables) with only a small amount of memory. As a result,
our exploit is stealthier and has fewer memory footprints. We also replace the
inefficient rowhammer algorithm that blindly picks up addresses to hammer with
an efficient one. Our algorithm selects suitable addresses based on an existing
timing channel.Comment: Preprint of the work accepted at the IEEE Transactions on Dependable
and Secure Computing 201
Traveling waves in lattice differential equations with distributed maturation delay
In this paper we derive a lattice model with infinite distributed delay to describe the growth of a single-species population in a 2D patchy environment with infinite number of patches connected locally by diffusion and global interaction. We consider the existence of traveling wave solutions when the birth rate is large enough that each patch can sustain a positive equilibrium. When the birth function is monotone, we prove that there exists a traveling wave solution connecting two equilibria with wave speed by using the monotone iterative method and super and subsolution technique, where is any fixed direction of propagation. When the birth function is non-monotone, we prove the existence of non-trivial traveling wave solutions by constructing two auxiliary systems satisfying quasi-monotonicity
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