Conformational Ensembles Explored Dynamically from Disordered Peptides Targeting Chemokine Receptor CXCR4

This work reports on the design and the synthesis of two short linear peptides both containing a few amino acids with disorder propensity and an allylic ester group at the C-terminal end. Their structural properties were firstly analyzed by means of experimental techniques in solution such as CD and NMR methods that highlighted peptide flexibility. These results were further confirmed by MD simulations that demonstrated the ability of the peptides to assume conformational ensembles. They revealed a network of transient and dynamic H-bonds and interactions with water molecules. Binding assays with a well-known drug-target, i.e., the CXCR4 receptor, were also carried out in an attempt to verify their biological function and the possibility to use the assays to develop new specific targets for CXCR4. Moreover, our data indicate that these peptides represent useful tools for molecular recognition processes in which a flexible conformation is required in order to obtain an interaction with a specific target.     

Apparent band-gap narrowing doping functions for silicon in the Dhariwal and Ojha's form facilitating solar cell modeling

It is shown that reported doping functions for apparent band-gap narrowing (ABGN) in silicon that are written in the Slotboom and De Graaff's form (Slotboom, De Graaff, Solid-State Electron. 19 (1976) 857) can be set in the Dhariwal and Ojha's form (Dhariwal, Ojha, Solid-State Electron. 25 (1982) 909) at all dopings without any significant deviation in their capability of fitting the experimental data. The use of the Dhariwal and Ojha's form is preferable because it allows for a straightforward application of the depletion approximation in the non-uniformly doped regions of silicon devices like ion-implanted and diffused solar cells, facilitating the device performance modeling and analysis. This is demonstrated by an application to the internal spectral responses of two ion-implanted silicon solar cells and a comparison with a modeling method which does not use the depletion approximation.     

Output-only analysis of structures with closely spaced poles

In the framework of the operational modal analysis, several approaches have been developed for estimating the modal parameters, i.e., natural frequencies, damping ratios, and mode shapes. Specifically, a technique capable to evaluate the biased (i.e., unscaled by a constant or an almost constant function) frequency response functions, FRFs, has been proposed. Assuming that only the responses of the structure are disposable, the technique allows one to estimate biased FRFs starting from the power spectral densities, PSDs, and applying the Hilbert transform. This paper deals with the estimates of the modal analysis parameters mentioned above. It is possible to obtain each single mode shape, from the singular vectors achieved by applying the singular value decomposition to the FRF matrix evaluated at the spectral line corresponding to the selected natural frequency. A special attention will be devoted to structures with coupled modes, i.e., closely spaced modes. Once the FRFs have been obtained, the natural frequencies and damping ratios could be achieved either in the frequency domain or in the time domain. Experimental tests, carried out on beams, plates and on the AB-204 helicopter blade, will be presented.     

金属燃料在不同气氛中的点火温度

利用自行设计的金属燃料点火温度测试系统,测试了常压下分别在空气和氧气中的镁包覆硼粉（包覆度20%）、镁粉及铝合金am-Al的点火温度。结果表明,与在空气中相比,3种金属燃料在氧气中的点火温度均有所降低;镁包覆硼粉有效降低了硼的燃点,促进了硼的点火和燃烧,且镁包覆硼粉在氧气中更易燃烧,其点火温度仅为约195.92℃;am-Al在氧气中可点燃,其点火温度低于镁,且燃烧放出的热量最高。在充足的氧气环境下,镁包覆硼粉及am-Al的点火温度均低于300℃,二者均可用作高热值金属燃料。     

Estimating Reduced-Reference Video Quality for Quality-Based Streaming Video

Reduced-reference (RR) video-quality estimators send a small signature to the receiver. This signature comprises the original video content as well as the video stream. RR quality estimation provides reliability and involves a small data payload. While significant in theory, RR estimators have only recently been used in practice for quality monitoring and adaptive system control in streaming-video frameworks. In this paper, we classify RR algorithms according to whether they are based on a) modeling the signal distortion, b) modeling the human visual system, or c) analyzing the video signal source. We review proposed RR techniques for monitoring and controlling quality in streaming video systems.     

Majority Logic Mapping for Soft Error Dependability

This work proposes the use of analog majority gates to implement combinational circuits that are intrinsically tolerant to transient faults. A new type of voter circuit, that uses some knowledge from the analog design arena is proposed, together with a new mapping approach to implement circuits given their input/output table. This new mapping approach is shown to compare favorably against a classic mapping. The implementation and validation of an adder circuit, using conventional triple modular redundancy (TMR), the classic mapping, and the proposed solution are analyzed, in order to confirm that the shown technique is indeed fault tolerant, and has advantages in terms of area and performance when compared to TMR. Finally, implementations of a subset of the ISCAS 85 benchmark circuits using TMR with the analog voter and the proposed approach are compared and the results analyzed.     

Directionlets: anisotropic multidirectional representation with separable filtering.

In spite of the success of the standard wavelet transform (WT) in image processing in recent years, the efficiency of its representation is limited by the spatial isotropy of its basis functions built in the horizontal and vertical directions. One-dimensional (1-D) discontinuities in images (edges and contours) that are very important elements in visual perception, intersect too many wavelet basis functions and lead to a nonsparse representation. To efficiently capture these anisotropic geometrical structures characterized by many more than the horizontal and vertical directions, a more complex multidirectional (M-DIR) and anisotropic transform is required. We present a new lattice-based perfect reconstruction and critically sampled anisotropic M-DIR WT. The transform retains the separable filtering and subsampling and the simplicity of computations and filter design from the standard two-dimensional WT, unlike in the case of some other directional transform constructions (e.g., curvelets, contourlets, or edgelets). The corresponding anisotropic basis unctions (directionlets) have directional vanishing moments along any two directions with rational slopes. Furthermore, we show that this novel transform provides an efficient tool for nonlinear approximation of images, achieving the approximation power O(N(-1.55)), which, while slower than the optimal rate O(N(-2)), is much better than O(N(-1)) achieved with wavelets, but at similar complexity.     

SAM Functionalized ZnO Nanowires for Selective Acetone Detection: Optimized Surface Specific Interaction Using APTMS and GLYMO Monolayers

In modern days, self‐assembled monolayer (SAM) functionalized surfaces represent an interesting tool for the development of ultrasensitive and selective sensing platforms for the detection of chemical substances such as biomolecules and gases. The ability of SAM to generate different functional groups on a single surface such as zinc oxide (ZnO) can be used to immobilize biomolecules and detect different analytes such as gases, proteins, etc. Herein, SAM functionalized ZnO NW‐based sensors are developed for acetone exhaled breath analysis. ZnO NWs are synthesized using a vapor–liquid–solid mechanism and their functionalization is done with two different SAMs, i.e., (3‐aminopropyl)trimethoxysilane (APTMS) and 3‐glycidoxypropyltrimethoxysilane (GLYMO). The enhancement in the electron depletion layer resistance (and also width) due to the capturing of electrons from the ZnO NWs surface by APTMS and GLYMO molecules is found to be the major reason in their superior sensing performances. The amine (–NH₂) groups of APTMS monolayer enhance the sensors selectivity toward acetone due to their reactions with acetone molecules, which produce imine in addition to water molecules. Moreover, after the functionalization with APTMS SAMs, the detection limits of the sensors are improved from 6 to 0.5 ppm, which makes these devices potential candidates for acetone exhaled breath analysis.     

Human-mobility enabled networks in urban environments: Is there any (mobile wireless) small world out there?

In the last 10 years, new paradigms for wireless networks based on human mobility have gained the attention of the research community. These paradigms, usually referred to as Pocket Switched Networks or Delay Tolerant Networks, jointly exploit human mobility and store-and-forward communications to improve the connectivity in sparse or isolated networks. Clearly, understanding the human mobility patterns is a key challenge for the design of routing protocols based on such paradigms. To this aim, we anonymously collected the positions of almost two thousand mobile phone users, spread over a metropolitan area greater than 200 km² for roughly one month. Then, with a multi-disciplinary approach, we estimated the mobility patterns from the collected data and, assuming Wi-Fi connectivity, we inferred the contact events among the devices to evaluate the connectivity properties of a human mobility-enabled wireless network. In a nutshell, the contribution of the paper is threefold: (i) it confirms some of the results obtained in smaller environments, such as the power-law distribution for contact and inter-contact times, allowing us to estimate the distribution parameters with high statistical significance; (ii) it addresses the feasibility of the transmission opportunities provided by human mobility to build a city-wide connected network for different forwarding strategies classes; (iii) it shows uncovered characteristics of the connectivity properties of human mobility, such as the presence of the small world phenomenon in wide-scale experiments.     

An analytical model based on the ETSI criteria for the evaluation of user satisfaction in UMTS

The analytical models commonly used for the evaluation of coverage and capacity in UMTS systems compute the BER probability at the radio interface. This approach is not in line with the ETSI guidelines, which state that the coverage and capacity of a UMTS system must be evaluated when the system is working with a given fraction of satisfied users. In this paper, we present an analytical model capable of taking into account user satisfaction. A comparison between analytical and simulation results confirms the validity of the proposed model. In addition, we discuss coverage-capacity curves as a function of the percentage of satisfied users, taking into account also the imperfections of the real power-control procedures. Paolo Giacomazzi received his degree in electrical engineering from the Politecnico di Milano, and the Master in information technology from Cefriel in 1990. From 1992 to 1998 he was Assistant Professor and now he his Associate Professor at the Politecnico di Milano. His research interests cover IP Differentiated and Integrated services, UMTS networks and fourth generation access networks. Luigi Musumeci joined the Electronic and Information Department of the Politecnico di Milano in 1991, where he is now Associate Professor. He received his degree in electrical engineering from the Politecnico di Milano in 1961. From 1968 to 1986 he was at Italtel where he was responsible for the design and implementation of Itapac, the Italian packet network. His research interests cover packet data networks, Internet, and wireless access networks. Giacomo Verticale is Assistant Professor at Politecnico di Milano. He graduated in Telecommunications Engineering in 1998. In 1999 he joined the CEFRIEL research center, where he worked on the Voice-over-IP and ADSL technologies. Verticale got his Ph.D. in 2003 from Politecnico di Milano defending a thesis on the performance of packet transmission in UMTS. His current interests focus on Quality of Service and on 4G wireless networks. He is member of IEEE and ACM.