Using Light-Switching Molecules to Modulate Charge Mobility in a Quantum Dot Array

We have studied the electron hopping in a two-CdSe quantum dot system linked by an azobenzene-derived light-switching molecule. This system can be considered as a prototype of a QD supercrystal. Following the computational strategies given in our recent work [Chu et al. J. Phys. Chem. C 115, 21409 (2011)], we have investigated the effects of molecular attachment, molecular isomer (trans and cis) and QD size on electron hopping rate using Marcus theory. Our results indicate that molecular attachment has a large impact on the system for both isomers. In the most energetically favorable attachment, the cis isomer provides significantly greater coupling between the two QDs and hence the electron hopping rate is greater compared to the trans isomer. As a result, the carrier mobility of the QD array in the low carrier density, weak external electric field regime is several orders of magnitude higher in the cis compared to the trans configuration. This is the first demonstration of mobility modulation using QDs and azobenzene that could lead to a new type of switching device.Comment: 8 pages, 3 figure

How people react to the ‘also recommended’ section of online stores

Retailers can take advantage of recommendation networks to drive product demand, write Zhijie Lin, Khim-Yong Goh and Cheng-Suang Hen

Dense trajectories and motion boundary descriptors for action recognition

This paper introduces a video representation based on dense trajectories and motion boundary descriptors. Trajectories capture the local motion information of the video. A dense representation guarantees a good coverage of foreground motion as well as of the surrounding context. A state-of-the-art optical flow algorithm enables a robust and efficient extraction of the dense trajectories. As descriptors we extract features aligned with the trajectories to characterize shape (point coordinates), appearance (histograms of oriented gradients) and motion (histograms of optical flow). Additionally, we introduce a descriptor based on motion boundary histograms (MBH) which rely on differential optical flow. The MBH descriptor shows to consistently outperform other state-of-the-art descriptors, in particular on real-world videos that contain a significant amount of camera motion. We evaluate our video representation in the context of action classification on eight datasets, namely KTH, YouTube, Hollywood2, UCF sports, IXMAS, UIUC, Olympic Sports and UCF50. On all datasets our approach outperforms current state-of-the-art results

Variability of Soft X-ray Spectral Shape in Blazars Observed by ROSAT

In paper 1 (Cheng et al. 2001) we have shown that the soft X-ray spectra of two types of Seyfert 1 galaxies statistically vary differently with increasing intensity. In order to understand how the spectrum of blazars changes, the spectral shape variability of 18 blazars observed by ROSAT/PSPC mode are studied by presenting the correlation of Hardness Ratio 1 versus Count Rates (HR1-CTs). According to our criteria, 10 blazars show a positive HR1-CTs relation, and only 2 blazars display an anti-correlation of HR1 versus CTs. The rest 6 blazars do not indicate any clear correlation. From these we can see that most blazars of our sample statistically show a hardening spectrum during overall flux increase, though some vary randomly. By investigating the photon index of these objects and different radiation theories, we argue that the dominance of the synchrotron or inverse Compton emission in the soft X-ray band may interpret the dichotomy of spectral variability well, and that different spectral variations might represent a sequence of synchrotron peaked frequency.Comment: 11 pages, 3 figures, CJA

Evaluations of the BGA Solder Ball Shape by Using Energy Method

Presented herein are the evaluation results of the BGA solder ball shape using energy method, two types of solder, viz. Sn37Pb and Sn80Pb, are selected .The geometry of the solder bump is firstly estimated using free computer software, the Surface Evolver, an interactive program which is an energy-based approach for the study of liquid droplet surfaces shaped by surface tension and other energies. The solder bump is then numerically constructed in a finite element model that simulates a BGA package. The influences of both upper and bottom solder pad radii, the surface tension on the balls, and the external load axially applied to the reflow solders on the stand-off height and the contact angle for both solder materials are investigated. The results show that for both solder materials, the stand-off height remains at a height under some pad radius. The height decreases as both upper and bottom pad radii increase. On the other hand, the contact angle presents a nearly inverse trend with respect to the pad radii. The study of the effect of surface tension reveals that at a constant pad radius, the solder ball stand-off height increases with surface tension; however, the trend becomes saturated eventually. The contact angle decreases as the surface tension becomes large. The trend also tends to be saturated. The results of the effects of axially applied load on the stand-off height and the contact angle show that as the applied load is increased so is the contact angle; nevertheless, the stand-off height becomes shorter

Role of PPARα and Its Agonist in Renal Diseases

Peroxisome proliferator-activated receptor (PPAR)-α, a member of a large nuclear receptor superfamily, plays a major role in the regulation of lipid metabolism. Recently, PPARα activation has been shown to confer additional benefits on endothelial function, kidney function, and anti-inflammation, suggesting that PPARα agonists may be good candidates for treating acute renal failure. In clinical application, PPAR-α activators, such as hypolipidemic drugs in fibric acid class, were proven to have therapeutic effects on metabolic syndrome and cardiovascular disease. This paper focuses on signaling pathways, ligand selectivity, and physio-pathological roles of PPARα in kidney diseases and the therapeutic utility of PPARα modulators in the treatment of diabetes and inflammation-induced nephropathy. Implication of new and more potent PPAR-α activators could provide important insights into the overall benefits of activating PPAR-α clinically for the treatment of dyslipidemia and the prevention of diabetic or inflammation-induced nephropathy in the future

Spatiotemporal dynamics of termite infestation in urban Araucaria cunninghamii: A case study in Taipei

Termite feeding on the trunk cross-sections of Araucaria cunninghamii in Taipei, Taiwan, was examined using 2D stress wave imaging (FAKOPP system). Six inspections were conducted at 2-month intervals to monitor six trees. 2D cross-sectional stress wave velocity images were created at different heights (30–180 cm) to assess termite feeding damage. Termite damage, quantified as damage ratio (DR, %), ranged from 0% to 55% across different trees and heights, with maximum increases of up to 21% in DR observed over a 2-month period. In the investigated cases, termites primarily fed on the interior of tree trunks. The feeding pattern typically extended longitudinally, then proceeded in a tangential (circular) direction, and finally moved radially. This study identified Coptotermes formosanus as a key termite species involved. Typically, termites prioritized feeding on the earlywood over the latewood. The periods with the highest damage to trunk cross-sections due to termite feeding occurred during seasons with higher temperatures and relative humidity. Damage initially appeared near the heartwood or the boundary between the heartwood and sapwood, gradually expanding into the heartwood. Of the six trees monitored for the full study duration (after one tree was felled for validation), subterranean termite tunneling was observed as the primary pattern in three trees, while aerial swarm invasion patterns were inferred for two trees based on initial damage locations

Tabernacles of the Spirit

In the classic tradition of the exploratory essay, George Gammack examines the theme of community in this paper. He details varied aspects of the creation of community among those who are retired, taking as its focus the Men’s Sheds movement. The paper explores the relationship between persons and community in later years, looking in particular at how those with a lifetime’s worth of skills and knowledge can continue to contribute to the life of a community. Along the way we are introduced to the work of authors such as Charles Taylor, Richard Niebuhr, Primo Levi, Seamus Heaney and Richard Sennett on the subject of work and what comes after it.Publisher PD