A data-driven multitone echo canceller

A data-driven echo canceller for full-duplex data transmission with multitone modulation is presented. This multitone echo canceller (MTEC) is not impaired by eigenvalue-spread problems that are inherent in signal-driven echo cancellers-it has numerical performance and cancellation range that equals, and in most cases exceeds, that of data-driven echo cancellers used in data transmission with baseband or quadrature amplitude modulation. The method makes use of frequency-domain updating, but time-domain implementation of the canceller. It introduces no delay into the received signal path and presents no special difficulties for interframe interpolation between near-end echo, far-end echo, or far-end data signal. The authors also investigate the fast initialization and the special case of far-end frequency offset in the echo signal     

X-linked juvenile retinoschisis: localization between (DXS1195, DXS418) and AFM291wf5 on a single YAC

We studied 17 pedigrees with 108 affected males with X-linked juvenile retinoschisis (RS; McKusick No. 31270) and have analyzed all of the known polymorphic markers in the RS region of Xp22.1-p22.2 between DXS987 and DXS41. By haplotype analyses we found 7 individuals who showed crossovers in this interval surrounding RS. We previously reported AFM291wf5 as the centromeric boundary, and this remains unchanged in the present study. A new recombination was identified on the telomeric side at (DXS1195, DXS418). Our data support the locus order Xpter--(DXS987, DXS207, DXS1053, DXS43)--(DXS1195, DXS418)--(RS, DXS257, DXS999)--(AFM291wf5, DXS443)--DXS1052--(DXS1226, DXS274, DXS41)--Xcen; loci grouped in parentheses could not be mutually ordered by our genetic data. Physical mapping has indicated a distance of at most 900-1,000 kb between (DXS1195, DXS418) and AFM291wf5. No recombination was observed between RS and DXS257 which lies in our new interval of interest, but one critical individual was not informative with this marker. Our data now define the smallest RS inclusion interval. This interval is contained on a single YAC from which we have identified expressed sequences as candidate genes for RS.     

Impact of apolipoprotein E polymorphism on lipoproteins and risk of myocardial infarction. The ECTIM Study

Human apolipoprotein (apo) E, a polymorphic protein with three common alleles, epsilon 2, epsilon 3, and epsilon 4, plays an important role in lipoprotein metabolism. This article describes the association of this polymorphism with lipids, apolipoproteins, and lipoproteins with a particular regard to lipoprotein particles, as defined by their apolipoprotein content, as well as the risk of myocardial infarction in a multicenter population-based case-control study (ECTIM study). In the ECTIM study, 574 male patients aged 25 to 64 were examined 3 to 9 months after myocardial infarction in four regions participating in the World Health Organization MONICA project: Belfast (Northern Ireland) and Lille, Strasbourg, and Toulouse (France). Control subjects (n = 722) were randomly selected from the regional populations. The distribution of apoE phenotypes was significantly different across the four control samples (P = .04), with a higher frequency of the epsilon 4 allele in Belfast (14.3%) than in Toulouse (8.2%). The association of apoE polymorphism with biological measurements was studied in the control groups (n = 640) after men with coronary heart disease or those taking hypolipidemic drugs were omitted, with the apoE3/3 phenotype as a reference after adjustment for concomitant factors. Individuals carrying the epsilon 2 allele had lower levels of plasma cholesterol, low-density lipoprotein cholesterol (LDL-C), and apoB and higher levels of triglycerides, very-low-density lipoprotein cholesterol (VLDL-C), apoC-III, apoE, lipoprotein (Lp) C-III:B, and Lp E:B. However, the effect of the epsilon 2 allele on triglyceride, VLDL-C, apoE, and Lp E:B parameters was heterogeneous across the populations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of composition and phase relations on mechanical properties and crystallization of silicate glasses

Crystallization, mechanical properties, and workability are all important for the commercialization and optimization of silicate glass compositions. However, the inter-relations of these properties as a function of glass composition have received little investigation. Soda-lime-silica glasses with Na₂O-MgO-CaO-Al₂O₃-SiO₂ compositions relevant to commercial glass manufacture were experimentally studied and multiple liquidus temperature and viscosity models were used to complement the experimental results. Liquidus temperatures of the fabricated glasses were measured by the temperature gradient technique, and Rietveld refinements were applied to X-Ray powder diffraction (XRD) data for devitrified glasses, enabling quantitative determination of the crystalline and amorphous fractions and the nature of the crystals. Structural properties were investigated by Raman spectroscopy. Acoustic echography, micro-Vicker's indentation, and single-edge-notched bend testing methods were used to measure Young's moduli, hardness, and fracture toughness, respectively. It is shown that it is possible to design lower-melting soda-lime-silica glass compositions without compromising their mechanical and crystallization properties. Unlike Young's modulus, brittleness is highly responsive to the composition in soda-lime-silica glasses, and notably low brittleness values can be obtained in glasses with compositions in the wollastonite primary phase field: an effect that is more pronounced in the silica primary phase field. The measured bulk crystal fractions of the glasses subjected to devitrification at the lowest possible industrial conditioning temperatures indicate that soda-lime-silica glass melts can be conditioned close to their liquidus temperatures within the compositional ranges of the primary phase fields of cristobalite, wollastonite, or their combinations.     

Toward a classification of discourse patterns in asynchronous online discussions

The goal of this study was to develop a classification for a range of discourse patterns that occur in text-based asynchronous discussion forums, and that can aid in the distinction of three modes of discourse: knowledge sharing, knowledge construction, and knowledge building. The dataset was taken from Knowledge Forum® databases in the Knowledge Building Teacher Network in Hong Kong, and included three discussion views created for different classes: Grade 5 Science, Grade 10 Visual Arts, and Grade 10 Liberal Studies. We used a combination of qualitative coding and narrative analysis as well as teachers’ understanding of online discourse to analyze student discussions. Nine discourse patterns were identified. These patterns revealed a variety of ways in which students go about their collaborative interactions online and demonstrated how and why students succeed or fail in sustaining collaborative interactions. This study extended the three modes of online discourse and developed different discourse patterns, which are efforts to provide instructional guidance. The implications of supporting productive discourse and the enactment of CSCL innovations in classrooms are discussed.     

真汉子与音响改装——DLS勇夺SQ组冠军

美国佛罗里达州的阿迪(Eddie DeJesus)对汽车音响改装知根知底。2001年产的雪佛兰(Chevy S-10)轻型小货车焕然一新,功率高达1600瓦特,阿迪感慨道:简直不可思议!阿迪(Eddie DeJesus)这样评价其A/V系统:在汽车音响竞赛中,它的配置并不复杂,别的改装车配置了很多高端设备,其系统线路精密。可这套音响系统的结构分布和器材搭配方面仍具有一定的参考价值。我们首要关切的是,尽量保留其原车配置,力求二者能够和气生财。     

众里寻她千百度——Chrysler 300 SRT8音响改装，欲与天公试比高

有一个问题一直困扰着卡特:在售后市场上,他不能淘到一款与6.1 Hemi相匹配的发电机。对于在2006年产的Chrysler 300 SRT8,卡特指出:原车160安培的交流发电机似乎有点勉为其难。除了引擎,他还想打造一个属于他自己的SQ音响系统。卡特称:我的最终目标是尽量保持原车面貌,遵循原车规     

补形箱制作续集

这个月,我们继续介绍2007年产Project Toyota Avalon(本田亚洲龙)的补形低音箱制作。该低音箱能够最大限度地利用汽车后尾箱,而又保持后尾箱的储物空间,它与汽车内饰非常合衬,且并不需做任何的切割工作,迄今为止,它是我最喜爱的一只低音箱。把它安装到许多的车辆上,它的效果都让人十分满意。如果您想加装低音箱和保留后尾箱的储物空间两不误,那么赶紧瞪大眼睛,打起十万分的精神,看看我们到底如何进行低音安装!     

海阔凭鱼跃——“小鱼儿”与音响改装

1989年,当时的卡车司机小鱼儿(戴夫·里韦拉的昵称)运货到波士顿的一家改装店。在这家店里的所见所闻赋予他无穷的想象力和灵感,至此,他的生命有了重大的转折。一年后,这个自学成才的改装技师,打造了平生的第一辆改装车——丰田花冠,并在当年的亚什卡(IASCA)赛事中荣获头名。打那以后,他就未曾停止过改装的步伐。上一次,我曾经跟小鱼儿打过照面,当时他升级改装的是自己日常座驾——福特Expedition(CA&E杂志2005年5月刊(注:美国《CAR AUDIO AND ELECTRONICS》简称CA&E)。那是他梦寐以求的原车升级改装,可以作为一个特殊的选择方案提供给福特。一直以来,他追求轻巧优雅和美观大方的改装理念,今年,他的1956年产Bel-Air被他摆弄得光彩照人,自然而然在Kenwood(建伍)CES电子展出尽了风头。我们和小鱼儿谈论了他的改装车及其未来的动向。