4,218 publications from this institution
Abstract High resolution and high efficiency planar display, one of the national priorities for advanced technologies and commercial applications, require highly efficient phosphor materials with crystalline monodispersive fine particles [1,2]. Europium oxide activated yttrium oxide (Y2O3:Eu) is a potential red-emission phosphor powders to be used in high efficiency electroluminescence and field emission displays. In this paper, a novel hydrolysis technique is employed to prepare phosphor particles of Y2O3: Eu, and the structure characterization is reported. In this synthesis technique, urea reacts with water to release OH−, cations of Y3+ and Eu3+ combine with OH− to form (Y1−xEux)(OH)3 precipitates. Y2O3 particles doped with Eu are formed after the precipitates being fired at a given temperature [3]. The particles prepared by this method are nearly spherical, and have an average diameter of ∼200 nm (Fig. 1). The distribution of particle sizes is narrow, and almost no agglomeration among particles is observed. The particle sizes remain approximately the same before (Fig. 1a) and after (Fig. 1b) being fired at 1200°C.
Contrastive decoding strategies are widely used to reduce object hallucinations in multimodal large language models (MLLMs). These methods work by constructing contrastive samples to induce hallucinations and then suppressing them in the output distribution. However, this paper demonstrates that such approaches fail to effectively mitigate the hallucination problem. The performance improvements observed on POPE Benchmark are largely driven by two misleading factors: (1) crude, unidirectional adjustments to the model's output distribution and (2) the adaptive plausibility constraint, which reduces the sampling strategy to greedy search. To further illustrate these issues, we introduce a series of spurious improvement methods and evaluate their performance against contrastive decoding techniques. Experimental results reveal that the observed performance gains in contrastive decoding are entirely unrelated to its intended goal of mitigating hallucinations. Our findings challenge common assumptions about the effectiveness of contrastive decoding strategies and pave the way for developing genuinely effective solutions to hallucinations in MLLMs.
Consideration of phase correlation between localized inelastic events occurring at different atomic sites remains one of the major obstacles in the dynamic calculations of either the Bloch wave theory or the generalized multislice theory. The former is restricted by the 3-D periodic assumption of the transition matrix and the latter is limited by the coherent treatment of the inelastic excitation within the same slice. To approach this problem properly, one starts from the coupled Schrodinger equations, Ψ 0 is the elastically scattered wave of energy E 0 , Ψ n describes the inelastically scattered wave of the nth excited state of energy E n = E 0 - ε n , and H'nm are the transition matrix elements. Taking Ψ n = ϕ n (z)Ψ n 0 ( r ), where Ψ n 0 ( r ) satisfies the elastic scattering Schrodinger equation of different wave vectors, and under the small angle approximation, Eq. (1) becomes Equation (2) can be solved with established elastic scattering theory, such as the multislice method.
Abstract The pulsed‐field gel electrophoresis (PFG) is a newly developing technique used in the fractionation of large DNA fragments. Advances in PFG demand a better understanding in the corresponding mechanisms of DNA dynamics in the gel network. Detailed experiments are needed to verify and to extend existing theoretical predictions as well as to find optimum conditions for effecient separation of large DNA fragments. In the present study, deformation of large DNA fragments (40 ∼ 70 kilobase pairs) imbedded in agarose gels were investigated by using the transient electric birefringence (TEB) technique under both singular polarity and bipolarity electric pulses at low applied electric field strengths ( E ≤ 5 V/cm). The steady‐state optical retardation (δ s ) of DNA molecules is linearly proportional to E 2 . At a given E , the amplitude of optical retardation [δ( t )] increases monotonically with the pulse width ( PW ) and then reaches a plateau value [δ( t = 0) = δ s ] where t = 0 denotes the time when the applied field is turned off or reversed. The field‐free decay time (τ ∼ a few minutes) is several orders of magnitudes slower than that from previous TEB observations using high electric field strengths ( E ∼ kV/cm) and short pulse widths ( PW ∼ ms). The degree of deformation (stretching and orientation) and the time of restoration to the equilibrium conformation of overall DNA chains have been related to δ and τ. In field inversion measurements, exponentially rising and linearly falling of birefringence signals in the presence of forward/inverse applied fields were observed. The rising and falling of birefringence signals were reproducible under a sequence of alternating pulses. Comparison of our results with literature findings and discussions with theories are presented.
