Analysis of observer performance in unknown-location tasks for tomographic image reconstruction

Our goal is to optimize regularized image reconstruction for emission tomography with respect to lesion detectability in the reconstructed images. We consider model observers whose decision variable is the maximum value of a local test statistic within a search area. Previous approaches have used simulations to evaluate the performance of such observers. We propose an alternative approach, where approximations of tail probabilities for the maximum of correlated Gaussian random fields facilitate analytical evaluation of detection performance. We illustrate how these approximations, which are reasonably accurate at low probability of false alarm operating points, can be used to optimize regularization with respect to lesion detectability.     

Corneal minimal visible lesion thresholds for 2.0 microm laser radiation

To support refinement of the ANSI Maximum Permissible Exposure safety limits, a series of experiments were conducted in vivo on Dutch Belted rabbit corneas to determine corneal minimum visible lesion thresholds for 2.0 microm continuous-wave laser irradiation. Single pulse radiant exposures were made at specified pulse durations of 0.1, 0.25, 0.5, 1.0, 2.0, and 4.0 s for spot 1/e(2) diameters of 1.17 mm and 4.02 mm. Threshold lesions were defined as the presence of a superficial surface whitening one hour after irradiation. Temperature measurements indicated that threshold peak temperatures were dependent on spot size and exposure duration. The exposure duration dependence of threshold average radiant exposure was described by an empirical power law equation: threshold radiant exposure[J/cm(2)]=a x exposure duration[s](b).     

Insights on interfacial charge transfer across P3HT/fullerene photovoltaic heterojunction from Ab initio calculations

The interfacial charge-transfer mechanism of the P3HT/fullerene photovoltaic heterojunction is elucidated using density functional theory calculations. Our findings indicate that an efficient adiabatic electron transfer is highly probable due to the presence of an extended electronic state that has a significant probability distribution across the interface in the lowest excited state. Furthermore, efficient exciton dissociation is possible because this bridging state has significant overlap with near-degenerate unoccupied states that are localized on the fullerene.     

Optical detection of ion-channel-induced proton transport in supported phospholipid bilayers

The integration of ion-channel transport functions with responses derived from nanostructured and nanoporous silica mesophase materials is demonstrated. Patterned thin-film mesophases consisting of alternating hydrophilic nanoporous regions and hydrophobic nanostructured regions allow for spatially localized proton transport via selective dimerization of gramicidin in lipid bilayers formed on the hydrophilic regions. The adjoining hydrophobic mesostructure doped with a pH sensitive dye reports the transport. The ease of integrating functional membranes and reporters through the use of patterned mesophases should enable high throughput studies of membrane transport.     

Uncovering forbidden optical transitions in PbSe nanocrystals

The 1S(h,e)-1P(e,h) exciton transition energy of PbSe nanocrystals was determined via two-photon photoluminescence excitation spectroscopy and was found to be in good agreement with predictions from a tight-binding calculation. The two-photon excitation peak occurs at energies very close to a strong feature in the one-photon absorption spectrum and suggests that it should be assigned as a formally forbidden S-P transition. Leading explanations for the unusual strength of the forbidden transition are discussed.     

Intermediate-band solar cells employing quantum dots embedded in an energy fence barrier

Power efficiencies>60% have been predicted for idealized quantum dot (QD) intermediate band solar cells. This goal has not yet been realized, due in part to nonidealities that result in charge trapping followed by recombination of photocarriers in the QDs, and the lack of an optimal materials combination. To eliminate charge trapping, a p+-i-n+ cell employing QDs buried within a high band gap barrier layer is proposed and analyzed. The maximum solar power conversion efficiency under AM1.5 spectral radiation of an example GaAs-based photovoltaic cell employing 10-20 layers of InAs QDs surrounded by AlxGa1-xAs barriers in the junction built-in depletion region can be as high as 45%. Higher efficiencies are anticipated for InP-based cells. This represents a significant improvement over GaAs homojunction cells with maximum efficiencies of <25%.     

Single functional group interactions with individual carbon nanotubes

Carbon nanotubes display a consummate blend of materials properties that affect applications ranging from nanoelectronic circuits and biosensors to field emitters and membranes. These applications use the non-covalent interactions between the nanotubes and chemical functionalities, often involving a few molecules at a time. Despite their wide use, we still lack a fundamental understanding and molecular-level control of these interactions. We have used chemical force microscopy to measure the strength of the interactions of single chemical functional groups with the sidewalls of vapour-grown individual single-walled carbon nanotubes. Surprisingly, the interaction strength does not follow conventional trends of increasing polarity or hydrophobicity, and instead reflects the complex electronic interactions between the nanotube and the functional group. Ab initio calculations confirm the observed trends and predict binding force distributions for a single molecular contact that match the experimental results. Our analysis also reveals the important role of molecular linkage dynamics in determining interaction strength at the single functional group level.     

Nanocarriers as an emerging platform for cancer therapy

Nanotechnology has the potential to revolutionize cancer diagnosis and therapy. Advances in protein engineering and materials science have contributed to novel nanoscale targeting approaches that may bring new hope to cancer patients. Several therapeutic nanocarriers have been approved for clinical use. However, to date, there are only a few clinically approved nanocarriers that incorporate molecules to selectively bind and target cancer cells. This review examines some of the approved formulations and discusses the challenges in translating basic research to the clinic. We detail the arsenal of nanocarriers and molecules available for selective tumour targeting, and emphasize the challenges in cancer treatment.     

2022年年初的新游戏测评与推荐

今年想必是次时代愈发成熟的一年,不仅索尼微软的装机量渐渐上去,各大厂商也会在这一年推出重量级的各种大作.面对应接不暇的阵容,我将推荐三大平台的一些佳作,希望给到挑选游戏的玩家朋友们一些指引与参考.相信《精灵宝可梦》一定是很多玩家的童年回忆,年初Switch平台最新作《精灵宝可梦阿尔宙斯》打出情怀牌的同时也在游戏的玩法上...     

变革时代中的城市文化保护

在以历史和文化保护作为先导来塑造城市的未来方面,南京以及它卓越的领导者发挥了积极的作用.作为这个城市的顾问之一,我有幸参加了南京的几个历史保护项目.对于许多在现代化和发展与文化保护之间寻求一种平衡的中国其他城市来说,南京可以作为一个楷模.今天介绍一点儿他们的经验.