2,693 research outputs found
New source for L-iditol and taxanes
We describe the first report of the recovery of L-iditol and Taxane from an angiosperm- Yunnanopilia longistaminata (W.Z.Li) C.Y.Wu et D.Z.Li (Opiliaceae). Two taxane compounds and L-iditol were isolated from the tender burgeon of Yunnanopilia longistaminata, and their structure were identified as Taxayunnansin B, Taxumairol E and L-iditol on the basis of NMR and MS spectrum, respectively. It is a new plant source for L-iditol and taxanes
Practical Fine-grained Privilege Separation in Multithreaded Applications
An inherent security limitation with the classic multithreaded programming
model is that all the threads share the same address space and, therefore, are
implicitly assumed to be mutually trusted. This assumption, however, does not
take into consideration of many modern multithreaded applications that involve
multiple principals which do not fully trust each other. It remains challenging
to retrofit the classic multithreaded programming model so that the security
and privilege separation in multi-principal applications can be resolved.
This paper proposes ARBITER, a run-time system and a set of security
primitives, aimed at fine-grained and data-centric privilege separation in
multithreaded applications. While enforcing effective isolation among
principals, ARBITER still allows flexible sharing and communication between
threads so that the multithreaded programming paradigm can be preserved. To
realize controlled sharing in a fine-grained manner, we created a novel
abstraction named ARBITER Secure Memory Segment (ASMS) and corresponding OS
support. Programmers express security policies by labeling data and principals
via ARBITER's API following a unified model. We ported a widely-used, in-memory
database application (memcached) to ARBITER system, changing only around 100
LOC. Experiments indicate that only an average runtime overhead of 5.6% is
induced to this security enhanced version of application
- …