Multiplex digital PCR: breaking the one target per color barrier of quantitative PCR

Quantitative polymerase chain reactions (qPCR) based on real-time PCR constitute a powerful and sensitive method for the analysis of nucleic acids. However, in qPCR, the ability to multiplex targets using differently colored fluorescent probes is typically limited to 4-fold by the spectral overlap of the fluorophores. Furthermore, multiplexing qPCR assays requires expensive instrumentation and most often lengthy assay development cycles. Digital PCR (dPCR), which is based on the amplification of single target DNA molecules in many separate reactions, is an attractive alternative to qPCR. Here we report a novel and easy method for multiplexing dPCR in picolitre droplets within emulsions-generated and read out in microfluidic devices-that takes advantage of both the very high numbers of reactions possible within emulsions (>10(6)) as well as the high likelihood that the amplification of only a single target DNA molecule will initiate within each droplet. By varying the concentration of different fluorogenic probes of the same color, it is possible to identify the different probes on the basis of fluorescence intensity. Adding multiple colors increases the number of possible reactions geometrically, rather than linearly as with qPCR. Accurate and precise copy numbers of up to sixteen per cell were measured using a model system. A 5-plex assay for spinal muscular atrophy was demonstrated with just two fluorophores to simultaneously measure the copy number of two genes (SMN1 and SMN2) and to genotype a single nucleotide polymorphism (c.815A>G, SMN1). Results of a pilot study with SMA patients are presented.     

Empirically supporting school STEM culture—The creation and validation of the STEM Culture Assessment Tool (STEM‐CAT)

School STEM Culture—an aspect of culture within a school community—is defined as the beliefs, values, practices, and resources in STEM fields as perceived by students, parents, teachers, and administrators and counselors within a school. This study validates the STEM Culture Assessment Tool (STEM‐CAT), an instrument intended to advance the use of the School STEM Culture construct within the research community. Internal consistency was determined through the use of Cronbach's alpha and factor analyses, and the instrument was found to be a reliable measure of School STEM Culture. The instrument can be used in future research to quantify School STEM Culture to determine if interventions change the culture of a school to further STEM education.     

On the possible production and detection of coherent low-energy neutrino beams

Seminal experiments are discussed to prove or disprove the possibility of producing and detecting collimated coherent beams of low-energy neutrinos with the assistance of lasers. Expressions are given for the relative probability that a laser-beam-aligned co- or counter-propagating neutrino-antineutrino pair is emitted instead of a laser photon, during stimulated de-excitations of lasable excited states inside a lasing medium. For a neodymium laser this probability is approximately 10^?7. To detect coherent beams of epithermal neutrinos and antineutrinos emitted from a pulsed high-power laser, it is anticipated that resonant non-absorptive stimulated de-excitations of lasing levels by neutrinos can be exploited to register their fly-through in a second near-threshold laser.     

适合消费电子产品的电流转换逻辑技术

消费电子和通信产业正见证着I／O解决方案从并行到高速串行的转变：能够降低成本、简化设计，并具备可延展性，满足全新带宽的要求。这类接口I／O技术的市场潜力巨大，包括移动电话、DVD-RW和高清晰度LCD电视机，而低功耗、低电磁干扰(EMI)和高数据吞吐量在这些应用中极为重要。因此，业界一直致力于设计和开发这些串行I／O，以低功耗提供高速的数据速     

High throughput screening for orphan and liganded GPCRs

GPCRs had significant representation in the drug discovery portfolios of most major commercial drug discovery organizations for many years. This is due in part to the diverse biological roles mediated by GPCRs as a class, as well as the empirical discovery that they have proven relatively tractable to the development of small molecule therapeutics. Publication of the human genome sequence in 2001 confirmed GPCRs as the largest single gene superfamily with more than 700 members, furthering the already strong appeal of addressing this target class using efficient and highly parallelized platform approaches. The GPCR research platform implemented at Amgen is used as a case study to review the evolution and implementation of available assays and technologies applicable to GPCR drug discovery. The strengths, weaknesses, and applications of assay technologies applicable to G alpha s, G alpha i and G alpha q-coupled receptors are described and their relative merits evaluated. Particular consideration is made of the role and practice of "de-orphaning" and signaling pathway characterization as a pre-requisite to establishing effective screens. In silico and in vitro methodology developed for rapid, parallel high throughput hit characterization and prioritization is also discussed extensively.     

Determination of 77Se-77Se and 77Se-13C J-coupling parameters for the clusters [Re5OsSe8(CN)6]3- and [Re4Os2Se8(CN)6]2-

We have investigated rarely observed 77Se J-couplings (spin-spin couplings) in the mixed-metal face-capped octahedral clusters [Re5OsSe8(CN)6]3- and [Re4Os2Se8(CN)6]2- at natural abundance. To the best of our knowledge, these are the first observations of Se-Se spin-spin interactions between mu3-Se sites, important for stereochemical assignments in hexarhenium analogues, Chevrel phase materials, and similar cluster materials. NMR techniques such as COSY, INADEQUATE, and 2D J-resolved spectroscopy have been used in conjunction to study these interactions. The two isomers (cis and trans) of [Re4Os2Se8(CN)6]2- were distinguishable, and selective isotopic labeling of [Re5OsSe8(CN)6]3- with 13CN ligands enabled resonances to be assigned by observing the 2J (Se-M-C) couplings. For [Re5OsSe8(CN)6]3-, two different 2J (Se-M-Se) couplings were measurable on a single cluster, and these are related to one another through spin-spin interactions across a face diagonal or along an edge of the cube of inner selenium ligands. A rigorous analysis based on combinatorial math has been invoked to assign the couplings on the basis of the probability of multiple-spin interactions. The face diagonal association is found to result in a J-coupling interaction larger in magnitude than that from coupling along an edge of the cube-information critical for making stereochemical assignments of selenium sites.     

纤巧型便携式设计中的多媒体信号路径

引言 把语音服务、高分辨率相机模块、MP3或PMP播放器功能整合在单个移动电话设计中,已成为未来中高端电话市场的发展趋势。除了超高的功率（〉700mW）立体声音频功能外,视频输出功能也出现在手机应用中,其输出仍主要是CVBS格式,而某些电话甚至提供S视频或模拟RGB输出。