A 43-Gb/s receiver (Rx) and transmitter (Tx) chip set for SONET OC-768 transmission systems is reported. Both ICs are implemented in a 0.18-/spl mu/m SiGe BiCMOS technology featuring 120-GHz f/sub T/ and 100 GHz f/sub max/. The Rx includes a limiting amplifier, a half-rate clock and data recovery unit, a 1:4 demultiplexer, a frequency acquisition aid, and a frequency lock detector. Input sensitivity for a bit-error rate less than 10/sup -9/ is 40 mV and jitter generation better than 230 fs rms. The IC dissipates 2.4 W from a -3.6-V supply voltage. The Tx integrates a half-rate clock multiplier unit with a 4:1 multiplexer. Measured clock jitter generation is better than 170 fs rms. The IC consumes 2.3 W from a -3.6-V supply voltage. 相似文献
Thread-level parallelism (TLP) has been extensively studied in order to overcome the limitations of exploiting instruction-level parallelism (ILP) on high-performance superscalar processors. One promising method of exploiting TLP is Dynamic Speculative Multithreading (D-SpMT), which extracts multiple threads from a sequential program without compiler support or instruction set extensions. This paper introduces Cascadia, a D-SpMT multicore architecture that provides multigrain thread-level support and is used to evaluate the performance of several benchmarks. Cascadia applies a unique sustainable IPC (sIPC) metric on a comprehensive loop tree to select the best performing nested loop level to multithread. This paper also discusses the relationships that loops have on one another, in particular, how loop nesting levels can be extended through procedures. In addition, a detailed study is provided on the effects that thread granularity and interthread dependencies have on the entire system. 相似文献
AbstractThe objective of this study was to compare spray-dried and freeze-dried extracts of Sennae fructus regarding the stability of the sennosides. Therefore, the influence of the addition of maltodextrin (MD) not only before the drying processes but also during fluidized bed granulation was investigated. Analysis of the hygroscopicities, the simultaneous TGA-DSC-MS data, and the influence of storage revealed that spray-dried extracts are more stable than freeze-dried extracts. The addition of MD led to an even better stability of the extracts. Lower amounts of MD are sufficient if applied onto the surface of the native extract during fluidized bed granulation. 相似文献
Since the yield condition for frame structures is non-linear, piecewise linear approximations are needed in order to apply linear optimization methods. Four approaches are presented and compared. After the theoretical consideration and comparison of the different approximation methods, they are applied to the robust design of an 18-bar frame in case of uncertainty. Here, the less restrictive methods yield the cheapest design, as expected. It will be shown, that the approximation from inside of first level does not cause much higher costs than the other methods. But since its constraints are sufficient in contrast to other approximations, it is recommended. 相似文献
Objective: The objective of this study was to characterize the properties of aqueous Sennae fructus extracts prepared by spray-drying at varying process conditions.
Significance: From an industrial point of view it is essential to develop a formulation which has a constant quality over the whole period of its specified shelf-life.
Method:Sennae fructus extracts were spray-dried with different atomizing gas pressures, pump feed rates, and inlet temperatures. The extracts were analyzed for their physical properties and stored at accelerated conditions. Sennoside degradation was monitored by HPLC analysis.
Results: An increase of the atomizing gas pressure had the most pronounced influence on the decrease of moisture content and particle size. An increase of the inlet temperature led to a decrease of moisture content and particle density, as well as an increase of smooth particle amount. An increase in the pump feed rate, increased the moisture content and resulted in stable hollow spheres. The different conditions also led to smooth or wrinkled particle surfaces, and to golfball, donut, and shard particle shapes. The chemical stability of the sennosides differed from each other after storage. Stability-reducing factors were the moisture content of the samples and their hygroscopicities, as well as different particle morphologies. These factors were influenced by the inlet temperature of the spray-drying process. High inlet temperatures led to a positive influence on dryness and particle morphology and therefore on the stability of the sennosides.
Conclusions: Variation of the process conditions affected the resulting particle properties and their storage stability of Sennae fructus extract. 相似文献
The inoculation into mice of genetically engineered tumour cells that secrete IL-2 or IFN gamma results in rejection, while unmodified parental tumour cells grow progressively. In vivo studies demonstrated synergy between IL-2 and IFN gamma leading to the rejection of the transduced tumour cells. IL-2 is required for T cell proliferation and differentiation. IFN gamma induced the upregulation of MHC class I molecules that present peptides to CD8+ T cells. Furthermore, IFN gamma can correct defects in antigen processing. Thus, for T cells, IL-2/IFN gamma-secreting double cytokine tumour cell vaccines might serve as class I+ peptide/antigen presenting depots for developing effector cells. In contrast to T cells, NK cells exert spontaneous killing and kill class I+ targets less well than those that are class I-. For this reason, they may actually have a detrimental effect by destroying a class I+ tumour cell vaccine before adequate T cell stimulation occurs. Based upon this rationale, we tested the hypothesis that an unrecognised benefit of increased class I expression by tumour cells in response to IFN gamma secretion would be to enable cytokine-secreting vaccine cells to resist destruction by NK cells. Our results demonstrated that T cells recognised tumour cells secreting IFN gamma better than those secreting IL-2. NK cells, in contrast, were inhibited by tumour cells that secreted IFN gamma, but not by those that secreted IL-2. The findings suggest that, in addition to upregulating adhesion molecules, MHC molecules, and correcting defects in antigen presentation pathways, IFN gamma secretion may protect tumour cell vaccines from early NK-mediated destruction, keeping them available for T cell priming. 相似文献