Eunsung Kim

SP600125 negatively regulates the mammalian target of rapamycin via ATF4‐induced Redd1 expression

SP600125 (SAPK Inhibitor II) is reported to function as a reversible ATP competitive inhibitor of c‐Jun N‐terminal kinase (JNK). In the present study, we show that SP600125 induces a dose‐dependent decrease in mTOR activity, as assessed by reduced phosphorylation of the downstream targets S6K1 and S6, and a significant increase in the expression of Redd1. Knockdown of Redd1 expression by siRNA resulted in a recovery of decreased S6 phosphorylation by SP600125. Overexpression of ATF4 upregulated the expression of Redd1, while suppression of ATF4 expression by siRNA enhanced the level of S6 phosphorylation by downregulating the SP600125‐induced increase in Redd1 expression. Together, these results indicate that SP600125 inhibits mTOR activity via an ATF4‐induced increase in Redd1 expression.

Crystal structure of α-hordothionin at 1.9 Å resolution

Crystal structure of ubiquitous toxin from barley α‐hordothionin (α‐HT) has been determined at 1.9 Å resolution by X‐ray crystallography. The primary sequence as well as the NMR solution structure of α‐HT firmly established that α‐HT belongs to a family of membrane active plant toxins–thionins. Since α‐HT crystallized in a space group (P41212) that is different from the space group (I422) of previously determined α1‐ and β‐purothionins, and visocotoxin A3, therefore, it provided independent information on protein–protein interactions that may be relevant to the toxin mechanism. The structure of α‐HT not only confirms overall architectural features (crambin fold) but also provides an additional confirmation of the role for crucial solute molecules, that were postulated to be directly involved in the mechanism of toxicity for thionins.

ReCon: A Fast and Reliable Replica Retrieval Service for the Data Grid

The Data Grid provides a scalable infrastructure for storage resources and data distribution management. It also supports a variety of scientific applications that require access to large amounts of data with various quality of service requirements. Replication is the process of storing data in different locations to reduce access latency, improve data locality, and increase robustness, scalability and performance for distributed applications. It is the core mechanism of the Data Grid in that it enables scalable and efficient sharing of large volumes of data. This paper focuses on finding the fastest and most reliable replica retrieval method in the Data Grid. For fast retrieval, we inspected, implemented, and tested various retrieval approaches, such as uniform, greedy, probe-based, latest-based, mean-based, and median-based. Experiments show that probe-based retrieval is the most appropriate approach for the Data Grid. For reliable retrieval, we introduce the recursive scheduling mechanism, which provides fault tolerant retrieval by rescheduling a failed subtransferring. Finally, we implemented ReCon (Replica Convoy) on Globus Toolkit version 4. The result is a fast and reliable replica retrieval service for the Data Grid.

Replica Aware Reliable File Transfer Service for the Data Grid

We focus on faster and more reliable third-party transfer in the data Grid with extending existing service - reliable file transfer service.

Asymmetry-aware load balancing for parallel applications in single-ISA multi-core systems

Contemporary operating systems for single-ISA (instruction set architecture) multi-core systems attempt to distribute tasks equally among all the CPUs. This approach works relatively well when there is no difference in CPU capability. However, there are cases in which CPU capability differs from one another. For instance, static capability asymmetry results from the advent of new asymmetric hardware, and dynamic capability asymmetry comes from the operating system (OS) outside noise caused from networking or I/O handling. These asymmetries can make it hard for the OS scheduler to evenly distribute the tasks, resulting in less efficient load balancing. In this paper, we propose a user-level load balancer for parallel applications, called the’ capability balancer’, which recognizes the difference of CPU capability and makes subtasks share the entire CPU capability fairly. The balancer can coexist with the existing kernel-level load balancer without detrimenting the behavior of the kernel balancer. The capability balancer can fairly distribute CPU capability to tasks with very little overhead. For real workloads like the NAS Parallel Benchmark (NPB), we have accomplished speedups of up to 9.8% and 8.5% in dynamic and static asymmetries, respectively. We have also experienced speedups of 13.3% for dynamic asymmetry and 24.1% for static asymmetry in a competitive environment. The impacts of our task selection policies, FIFO (first in, first out) and cache, were compared. The use of the cache policy led to a speedup of 5.3% in overall execution time and a decrease of 4.7% in the overall cache miss count, compared with the FIFO policy, which is used by default.