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1.
2.
To probe for a lever arm action in the kinesin stepping mechanism, we engineered a rodlike extension piece into the tail of rat kinesin at various points close to the head-tail junction and measured its effects on the temperature dependence of velocity in microtubule gliding assays. The insert comprised two contiguous alpha-actinin triple-coil repeats and was predicted to fold into a stiff rodlike module about 11 nm long. The effects of this module were greater the closer it was placed to the head-tail junction. When inserted distal to the head-tail junction, at Asn401 in the dimeric K partial differential401GST, the insert had no effect. When inserted closer to the heads at Val376 into K partial differential376GST, the insert slowed progress below 22 degreesC but accelerated progress to approximately 125% of wild type above 22 degreesC. The most dramatic effect of the synthetic lever occurred when it was inserted very close to the head-neck junction, at Glu340 into the single-headed construct K partial differential340GST. This construct was immotile without the insert, but motile with it, at about 30% of the velocity of the dimeric control. The alpha-actinin module thus confers some gain-of-function when inserted close to the head-neck junction but not when placed distal to it. The data exclude the presence of a lever arm C-terminal to Val376 in the kinesin tail but suggest that a short-throw lever arm may be present, N-terminal to Val376 and contiguous with the head-neck junction at Ala339. 相似文献
3.
Mazumdar Debasis Mitra Soma Ghosh Kuntal Bhaumik Kamales 《Pattern Analysis & Applications》2021,24(3):1403-1425
Pattern Analysis and Applications - The pattern of spatial contrast discontinuities in natural images has been analysed in the present work, and based on it, a new adaptive model of the... 相似文献
4.
Anirban Sengupta Chandan Mazumdar Aditya Bagchi 《Journal of Network and Systems Management》2011,19(3):319-342
From information security point of view, an enterprise is considered as a collection of assets and their interrelationships.
These interrelationships may be built into the enterprise information infrastructure, as in the case of connection of hardware
elements in network architecture, or in the installation of software or in the information assets. As a result, access to
one element may enable access to another if they are connected. An enterprise may specify conditions on the access of certain
assets in certain mode (read, write etc.) as policies. The interconnection of assets, along with specified policies, may lead
to managerial vulnerabilities in the enterprise information system. These vulnerabilities, if exploited by threats, may cause
disruption to the normal functioning of information systems. This paper presents a formal methodology for detection of managerial
vulnerabilities of, and threats to, enterprise information systems in linear time. 相似文献
5.
Sumit Misra Sanjoy Kumar Saha Chandan Mazumdar 《Innovations in Systems and Software Engineering》2017,13(4):261-269
Multiple data streams coming out of a complex system form the observable state of the system. The streams may correspond to various sensors attached with the system or outcome of internal processes. Such stream data may consist of multiple attributes and may differ in terms of their frequency of generation and observation. The streams may have dependency among themselves. One will have to rely on such data streams for monitoring the health of the system or to take any corrective measure. Predicting the value of certain stream data is an important task that can help one to take decision and act accordingly. In this work, a simple but generic visualization of a complex system is presented and thereafter a linear regression-based dynamic model for short-term prediction is proposed. The model is based on the past history of the attributes of multiple streams as suggested by the domain experts. But, it automatically determines the meaningful attributes and reformulates the model. The model is also re-computed if the prediction error exceeds the allowable tolerance. All these make the model dynamic. Experiment is carried out with stock market data streams to predict the close value well in advance. It is observed that in terms of quality of prediction and performance metric, the proposed model is quite effective. 相似文献
6.
Zinc telluride thin films have been grown at room temperature and higher temperature substrates by thermal evaporation technique
in a vacuum of 10-6 torr. A main peak in the photocurrent is observed at 781 nm (1.58 eV) with two lower amplitude peaks on the lower wavelength
side and one on higher wavelength side. The evaluated thermal activation energy is found to correspond well with the main
spectral peak. From these studies it can be inferred that temperatures up to 453 K is still in the extrinsic conductivity
region of the studied ZnTe thin films.
The paper was presented at the 6th Asian Thermophysical Properties Conference (6th ATPC), held at Gauhati University, during
8–11 October 2001. 相似文献
7.
The rapid evolution of computing and communication technologies and their standardizations have made the boom in e-commerce
possible. Lowering of the cost of operation, increase in the speed of transactions, and easy global reach to customers and
vendors have been the reasons for the overwhelming popularity of this new way of commerce. This article examines the issues
related to the security of the assets and transactions in the e-commerce components and activities. Since large public money
is involved in the transactions, the role of information security and privacy is not exaggerated in this kind of business.
After examining the technologies used in e-commerce, the article goes on to identify the security requirement of e-commerce
systems from perceived threats and vulnerabilities. Then e-commerce security is viewed as an engineering management problem
and a life cycle approach is put forward. How the e-commerce systems can be made secure using the life cycle approach is outlined.
The relevant standards and laws are also discussed in the perspective of e-commerce. The article closes with some future research
directions and conclusions. 相似文献
8.
In this paper, a stream-based dataflow architecture is proposed, and its simulation model, which has helped to evaluate the effectiveness of the proposed architectural concept, is discussed. The machine integrates the conventional Von Neumann type of control flow subsystem with a dataflow processing element of token storage type. The control flow unit tackles the dynamic nature of the stream structure including input/output whereas the dataflow unit does the computation part in an applicative style. A pipelined version of the stream machine is also discussed. The effectiveness of the machine is studied by running a few example programs in the simulated machine. The machine is expected to be useful in real time signal processing applications. 相似文献
9.
Subrata Mallick Satyanarayan Pattnaik Kalpana Swain Pintu K. De Arindam Saha Pushpen Mazumdar 《Drug development and industrial pharmacy》2013,39(7):726-734
This present study is a preliminary exploration of the affinity between a carboxylic model drug ibuprofen and aluminum hydroxide. Ibuprofen was comilled with aluminum hydroxide in different weight ratios in the solid state and was characterized by scanning electron microscopy (SEM), X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), and in vitro dissolution studies. XRD and SEM studies indicated complete interaction of ibuprofen with aluminum hydroxide and complete amorphization of aluminum hydroxide–ibuprofen complexed salt as well, on comilling with aluminum hydroxide at 1:2 ratio. FTIR data showed the disappearance of acid carbonyl peak with the appearance and the corresponding increase in absorbance of new signal at 1,682 cm?1 in the 1:1 and 1:2 ibuprofen–aluminum hydroxide-comilled powder. The accompanied increase in the absorbance of carboxylate peak in the ibuprofen–aluminum hydroxide physical mixture, and 1:0.1, 1:0.5, 1:1, and 1:2 (IBApm, and IB1A0.1, IB1A0.5, IB1A1, and IB1A2, respectively) comilled powder indicated an acid–base reaction between ibuprofen and aluminum hydroxide. On storage at 40°C and 75% relative humidity (RH) for 10 weeks, XRD study showed the absence of reversion to the crystalline state and FTIR data revealed continued increase of new signal at 1,682 cm?1 relative to carboxylic acid peak and no reappearance of carboxylic acid peak. In vitro dissolution studies revealed that the percent release of ibuprofen from the aluminum hydroxide-comilled powder is in the following order: IB1A2 < IB1A1 < ibuprofen crystal < ibuprofen milled alone < IB1A0.1 < IB1A0.5. Aluminum metal cation might have interacted to form a complex through the carboxyl and carbonyl groups of ibuprofen. Improved dissolution of drug associated with IB1A0.1 and IB1A0.5 is because of the absence of a new signal at 1,682 cm?1 and improved amorphization of the drug to some extent. Dissolution of drug affected in IB1A2 and IB1A1 may be because of the insoluble stable complex formation. 相似文献
10.