Inactivation of Staphylococcus hyicus lipase by hexadecylsulfonyl fluoride: evidence for an active site serine

The Staphylococcus hyicus lipase is an acyl hydrolase with broadsubstrate specificity including neutral glycerides and phospholipids.To obtain further insight into the mechanism of action of thisenzyme, we tested several sulfonyl fluorides as active site-directedinhibitors. The enzyme is resistant to the well-known serineprotease/esterase inhibitor phenylmethanesulfonyl fluoride (PMSF),but is rapidly inactivated by hexadecylsulfonyl fluoride. Thekinetics of inactivation were studied in Triton X-100 micelles.Inactivation is fast and the rate of inactivation is constantover the pH range where this lipase is active. Metal ions likeCa²⁺ and Sr²⁺ do not appreciably influence the rate of inactivation,although the enzymatic activity is significantly increased,suggesting a structural role for these ions. The S.hyicus lipasecontains a consensus sequence G-H/Y-S-X-G. Substitution by site-directedmutagenesis of this serine (Ser369) by a cysteine resulted ina mutant with only 0.2% residual activity. The activity of thismutant could not be inhibited with water-soluble sulfhydrylreagents either in the presence or absence of Triton X-100 micelles.In the presence of Triton X-100 micelles, inactivation of themutant occurred with 4-nitrophenylhexadecyl disulfide (t_1/2= 125 min) while the wild-type enzyme does not react at all.We conclude that Ser369 is the active site residue and thatin water this residue is inaccessible. Only after interfacialactivation Ser369 (or Cys369) becomes exposed and reacts withirreversible inhibitors.     

FacetAtlas: multifaceted visualization for rich text corpora

Documents in rich text corpora usually contain multiple facets of information. For example, an article about a specific disease often consists of different facets such as symptom, treatment, cause, diagnosis, prognosis, and prevention. Thus, documents may have different relations based on different facets. Powerful search tools have been developed to help users locate lists of individual documents that are most related to specific keywords. However, there is a lack of effective analysis tools that reveal the multifaceted relations of documents within or cross the document clusters. In this paper, we present FacetAtlas, a multifaceted visualization technique for visually analyzing rich text corpora. FacetAtlas combines search technology with advanced visual analytical tools to convey both global and local patterns simultaneously. We describe several unique aspects of FacetAtlas, including (1) node cliques and multifaceted edges, (2) an optimized density map, and (3) automated opacity pattern enhancement for highlighting visual patterns, (4) interactive context switch between facets. In addition, we demonstrate the power of FacetAtlas through a case study that targets patient education in the health care domain. Our evaluation shows the benefits of this work, especially in support of complex multifaceted data analysis.     

Idle-Channel Noise Characteristic of a Delta Modulator with Step Imbalance and Quantizer Hysteresis

In 1969 Iwersen [4] analyzed the quantizing noise (assuming no slope overload) associated with a delta modulator (DeltaM) with step-size imbalance. In this concise paper we consider the effects of both step-size imbalance and quantizer threshold hysteresis onDeltaMquantizing noise. The analysis is restricted to the important case of zero input signal. For this case we extend Iwersen's work to show that quantizer threshold hysteresis can significantly change the spectral shape of the idle channel noise. Our approach is to first construct two locus functions, one for the samples (of the steady-state noise waveform) taken at arbitrarily defined even sampling times and one for those taken at the odd sampling times. The noise waveform is then obtained as a superposition of interleaved samples of the even and odd loci. It is shown that the noise spectrum has a discrete tonal struture whose frequencies are independent of hysteresis and are determined solely by step imbalance as in Iwersen's analysis. Hysteresis changes the magnitude and phase of the discrete tones. We characterize the tone magnitude changes due to hysteresis and show that hysteresis can amplify, attenuate, or completely eliminate a tone. We present curves which specify the tone magnitude attenuation as a function of step imbalance ε, average step size σ, and hysteresish. We also calculate PT, the total noise power in the baseband up to half the sampling frequency. It is shown that for0 leq h leq epsilon,P_{T} = sigma^{2}/3independent ofhand ε ;forh > epsilon, PTis an increasing function ofepsilon/sigmaandh/epsilon.     

Real time electron tunneling and pulse spectroscopy in carbon nanotube quantum dots

We investigate a quantum dot (QD) in a carbon nanotube (CNT) in the regime where the QD is nearly isolated from the leads. An aluminum single electron transistor (SET) serves as a charge detector for the QD. We precisely measure and tune the tunnel rates into the QD in the range between 1 kHz and 1 Hz, using both pulse spectroscopy and real-time charge detection, and measure the excitation spectrum of the isolated QD.     

DICON: interactive visual analysis of multidimensional clusters

Clustering as a fundamental data analysis technique has been widely used in many analytic applications. However, it is often difficult for users to understand and evaluate multidimensional clustering results, especially the quality of clusters and their semantics. For large and complex data, high-level statistical information about the clusters is often needed for users to evaluate cluster quality while a detailed display of multidimensional attributes of the data is necessary to understand the meaning of clusters. In this paper, we introduce DICON, an icon-based cluster visualization that embeds statistical information into a multi-attribute display to facilitate cluster interpretation, evaluation, and comparison. We design a treemap-like icon to represent a multidimensional cluster, and the quality of the cluster can be conveniently evaluated with the embedded statistical information. We further develop a novel layout algorithm which can generate similar icons for similar clusters, making comparisons of clusters easier. User interaction and clutter reduction are integrated into the system to help users more effectively analyze and refine clustering results for large datasets. We demonstrate the power of DICON through a user study and a case study in the healthcare domain. Our evaluation shows the benefits of the technique, especially in support of complex multidimensional cluster analysis.     

访建筑师亚当·西尔维斯特

建筑师亚当·西尔维斯特（Ａｄａｍ　Ｓｙｌｖｅｓｔｅｒ）生于１９４３年,后获建筑学博士学位,早年曾在著名的公益设计公司ＩＰＡＲＴＥＲＶ工作多年,任该公司的建筑设计师。９０年代初期,他加入ＴＥＲ４设计公司,担任这家小型设计公司的首席建筑设计师。１９９７年匈牙利建筑师议院布达佩斯分院宣布成立,成为匈牙利建筑师议院最大的独立分支机构,亚当·西尔维斯特任职该分支机构的主席至今。在此,《当代匈牙利建筑》杂志编辑格茨·埃斯特对亚当·西尔维斯特就匈牙利建筑师议院和他的一些设计作品进行了访谈。     

A 10-GHz SiGe BiCMOS phase-locked-loop frequency synthesizer

A SiGe BiCMOS phase-locked-loop (ILL) circuit is presented. A maximum operational frequency of 10 GHz and a current consumption of 7.6 mA, i.e., 17 mW, is demonstrated. For a 9-mW low-power version, a maximum frequency of 4.7 GHz is determined. In a GSM direct conversion application, an in-band phase noise of -79 dBc/Hz at 2 kHz and a spurious suppression of -75 dBc at 400 kHz was measured at 3.4 GHz, which corresponds to a PLL phase noise floor of -214 dBc/Hz. For low-power applications, the PLL can be operated at supply voltages as low as 2.2 V and at RF input powers as low as -20 dBm while having a large output voltage range of 0.2 V to (V_cc-0.3 V). This demonstrates the speed and power advantage of the SiGe BiCMOS over Si BiCMOS and CMOS technologies for wireless communications     

Development of patient medication instruction cards

The development of patient medication instruction cards for use in patient education is described. Writing of the cards, their use in practice and predischarge teaching are discussed.     

Power line channel characteristics and their effect on communication system design

The development of power line communication systems requires detailed knowledge of the channel properties, such as transfer function, interference scenario, and channel capacity in order to choose suitable transmission methods. This article presents appropriate power line channel models, which form the basis for the design of a channel emulator. Such a device turns out to be extremely helpful for various tests and the comparison of performance of different communication systems. A basic estimation of the power line channel capacity clearly demonstrates their enormous potential for high-speed communication purposes. Eventually, an evaluation of different modulation schemes is carried to optimize PLC system design.