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Clustering has long been an important data processing task in different applications. Typically, it attempts to partition the available data into groups according to their underlying distributions, and each cluster is represented by a center or an exemplar. In this paper, a new clustering algorithm called gravitational-force-based affinity propagation clustering (GFAPC) is proposed, based on the well-known Newton's law of universal gravitation. It views the available data points as nodes of a network (or planets of a universe) and the clusters and their corresponding exemplars can be obtained by transmitting affinity messages based on the gravitational forces between data points in a network. While GFAPC is inspired by the recently proposed affinity propagation clustering (APC) approach, it provides a new definition of the similarity between data points which makes the APC process more convincing and at the same time facilitates the differentiation of data points' importance. The experimental results show that the GFAPC algorithm, with comparable clustering accuracy, is even more efficient than the original APC approach.

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First-principles calculations based on all-electron density functional theory are performed on hydrogenated graphene/boron nitride (BN) bilayer and graphene/BN multilayers to exploit the effects of the heterogeneous interface and external bias voltage on controlling their electronic properties. After hydrogenation, the emerging of the dipoles at the interface induced by the charge transfer between the graphene and the BN layer introduces a built-in potential difference, which plays a critical role in determining the band gaps of the resulting system. Tuning this internal potential difference through changing the number of BN layers or an external bias allows continuous modulation of the band gaps and leads to a linear transition from semiconductors to metals. [ABSTRACT FROM AUTHOR]

A near stoichiometric LiNbO3 single crystal has been grown by the Czochralski method from a 58.5% Li melt hold in a large platinum crucible. High resolution X-ray rocking curves of 30$ \bar 3 $0 and 0006 reflections indicated that the near stoichiometric LiNbO3 crystal possesses the high structural quality. Compared with the congruent LiNbO3, the near stoichiometric LiNbO3 possesses shorter ultraviolet absorption edge, thus higher Li concentration. The OH– infrared absorption band analyses showed that the Li concentration in the near stoichiometric LiNbO3 crystal is higher than that in the congruent LiNbO3 crystal. This result is in good agreement with that of the ultraviolet absorption edge. The electro-optic (EO) coefficient γ22 of the near stoichiometric LiNbO3 crystal was measured to be 6.75 pm/V higher than that of congruent LiNbO3 crystal. It also proves the near stoichiometric LiNbO3 electro-optic Q-switched requires a low driving voltage and it is advantageous for the device performance. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

In this paper we present an experimental investigation of the identification of crack location and size. By providing the first three natural frequencies through vibration measurements, curves of crack equivalent stiffness versus crack location are plotted, and the intersection of the three curves predicts the crack location and size. In the experiments, the cracked specimens were made using a wire-cut electrical discharge machine, and the cantilever beams were excited next to the free end by means of an impulse force hammer. In order to obtain the accurate natural frequencies from the transient signal measured, the method of zoom fast Fourier transform is adopted to improve frequency resolution. From experimental results, it is observed that the identification errors of crack location and size are less than 2% and 4%, respectively. The effectiveness of crack identification through vibration measurements is verified. [ABSTRACT FROM AUTHOR]

A hybrid integrated dual-parallel modulated DFB laser is experimentally demonstrated. Utilizing the proposed method, the nonlinear distortions of the DFB laser, including the second harmonic distortion (2HD) and the third-order intermodulation distortion are suppressed significantly. Comparing with the single modulated DFB laser, the 2HD is reduced by 8.6 dB and the spurious free dynamic range is increased from 87.2 dB·Hz2/3 to 90.3 dB·Hz2/3. [ABSTRACT FROM AUTHOR]

The thermal evolutions of optical properties and phase transitions of PbZr1−xTixO3 (PZT) ceramics as the functions of Ti compositions have been systemically explored by means of temperature dependent ellipsometric spectra and first-principles calculations. Two interband electronic transitions have been obtained by fitting the second derivatives of the complex dielectric functions and the physical origins can be explained with the aid of theoretical calculations. Based on the interband transitions, the phase diagram of PZT ceramics can be well-established. Importantly, dramatic Zr-rich ion clusters at 70 K and two intermediate regions are captured. The Zr-side intermediate phase is attributed to the tilting competitions of high [FER(HT)] and low [FER(LT)] temperature rhombohedral structures. Moreover, a wider range of the monoclinic (M) region from x  =  0.28 to 0.50 has been determined than previously reported. Interestingly, one can conclude that a more superior performance of PZT may be obtained with the larger M domains relying on external strains or fields. [ABSTRACT FROM AUTHOR]

An index-coupled DFB laser with a sampled grating has been designed and fabricated. The key concept of the approaches is to utilize the +1st-order reflection of the sampled grating for laser operation, and use a conventional holographic exposure combined with the usual photolithography to form the sampled grating. The typical threshold current of the sampled grating DFB laser is 25 mA, and the optical output is about 10 mW at the injected current of 100 mA. The lasing wavelength of the device is 1.5314 µm, which is the +1st-order peak of the sampled grating. [ABSTRACT FROM AUTHOR]

The Al-polar surfaces of AlN wafers cut from physical vapor transport grown crystals were lapped and polished. Polishing procedures were developed to produce surfaces for epitaxial growth. The surface scratches and subsurface damage caused by mechanical polishing were removed by a final chemical mechanical polishing (CMP) process, which yielded a perfect surface ready for epitaxial growth. After CMP the average root mean square surface roughness on a 5 µm × 5 µm area was 0.1 nm. Characterization of the polished surfaces by electron back scatter diffraction and cathodoluminescence showed no subsurface damage. The difference of orientation dependent material removal rate during CMP went up with the increase of the misorientation from (0001) surface. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Importance: Cerebral malaria (CM) is the deadliest complication of malaria infection with an estimated 15%-25% mortality. Even with timely and effective treatment with antimalarial drugs such as quinine and artemisinin derivatives, survivors of CM may suffer long-term cognitive and neurological impairment. Here, we show that human apolipoprotein E variant 2 (hApoE2) protects mice from experimental CM (ECM) via suppression of CD8 + T cell activation and infiltration to the brain, enhanced cholesterol metabolism, and increased IFN-γ production, leading to reduced endothelial cell apoptosis, BBB disruption, and ECM symptoms. Our results suggest that hApoE can be an important factor for risk assessment and treatment of CM in humans., Competing Interests: The authors declare no conflict of interest.