Electric Current Focusing Efficiency in Graphene Electric Lens

In present work, we theoretically study the electron wave's focusing phenomenon in a single layered graphene pn junction(PNJ) and obtain the electric current density distribution of graphene PNJ, which is in good agreement with the qualitative result in previous numerical calculations [Science, 315, 1252 (2007)]. In addition, we find that for symmetric PNJ, 1/4 of total electric current radiated from source electrode can be collected by drain electrode. Furthermore, this ratio reduces to 3/16 in a symmetric graphene npn junction. Our results obtained by present analytical method provide a general design rule for electric lens based on negative refractory index systems.Comment: 13 pages, 7 figure

A Recipe for Watermarking Diffusion Models

Diffusion models (DMs) have demonstrated advantageous potential on generative tasks. Widespread interest exists in incorporating DMs into downstream applications, such as producing or editing photorealistic images. However, practical deployment and unprecedented power of DMs raise legal issues, including copyright protection and monitoring of generated content. In this regard, watermarking has been a proven solution for copyright protection and content monitoring, but it is underexplored in the DMs literature. Specifically, DMs generate samples from longer tracks and may have newly designed multimodal structures, necessitating the modification of conventional watermarking pipelines. To this end, we conduct comprehensive analyses and derive a recipe for efficiently watermarking state-of-the-art DMs (e.g., Stable Diffusion), via training from scratch or finetuning. Our recipe is straightforward but involves empirically ablated implementation details, providing a foundation for future research on watermarking DMs. The code is available at https://github.com/yunqing-me/WatermarkDM

On Evaluating Adversarial Robustness of Large Vision-Language Models

Large vision-language models (VLMs) such as GPT-4 have achieved unprecedented performance in response generation, especially with visual inputs, enabling more creative and adaptable interaction than large language models such as ChatGPT. Nonetheless, multimodal generation exacerbates safety concerns, since adversaries may successfully evade the entire system by subtly manipulating the most vulnerable modality (e.g., vision). To this end, we propose evaluating the robustness of open-source large VLMs in the most realistic and high-risk setting, where adversaries have only black-box system access and seek to deceive the model into returning the targeted responses. In particular, we first craft targeted adversarial examples against pretrained models such as CLIP and BLIP, and then transfer these adversarial examples to other VLMs such as MiniGPT-4, LLaVA, UniDiffuser, BLIP-2, and Img2Prompt. In addition, we observe that black-box queries on these VLMs can further improve the effectiveness of targeted evasion, resulting in a surprisingly high success rate for generating targeted responses. Our findings provide a quantitative understanding regarding the adversarial vulnerability of large VLMs and call for a more thorough examination of their potential security flaws before deployment in practice. Code is at https://github.com/yunqing-me/AttackVLM.Comment: NeurIPS 202

Two-Link Flexible Manipulator Modeling and Tip Trajectory Tracking Based on Absolute Nodal Coordinate Method

Abstract It has been demonstrated that the absolute nodal coordinate formulation (ANCF) proposed recently in literature can be used to exactly describe the flexible multibody system unlike traditional methods such as the floating coordinate method and assumed mode method. Therefore, in this paper a new dynamic modeling technique for a two-link flexible manipulator based on absolute nodal coordinate method is proposed. The link shear effect was taken into account by using the 2D ANCF shear beam element. The resulting state equation can be explicitly described by generalized coordinate since the system mass matrix is constant in the ANCF framework. The proposed method is validated through the two-link flexible manipulator tip circle and square trajectory tracking control simulations by using a simple PD controller. To improve computational efficiency, the invariant matrix method and the Broyden quasi-Newton method are introduced. To improve the tracking accuracy, different PD parameters in different simulation periods are used. The simulation results indicate that modeling and controlling the flexible manipulator based on the ANCF is effective

Growth, Nutrient Uptake, and Foliar Gas Exchange in Pepper Cultured with Un-composted Fresh Spent Mushroom Residue

Spent mushroom substrate (SMS) can be used as the component of growing medium for the culture of crop plants. Fresh SMS may have the potential as an alternative to peat to raise horticultural plants. In this study, five container media characterized by the proportions of SMS to commercial peat in 0% (control), 25%, 50%, 75%, and 100% were used to raise pepper (Capsicum annum L.) plants. Initial SMS was found to have low available nitrogen (N) content (<20 mg kg-1) but moderate extractable phosphorus (P) content (900 mg kg-1). In the second month photosynthetic rate was found to decline in the 75% treatment. At harvest in the third month, plants in the 100% treatment nearly died out. The 25% treatment resulted in the highest height (19 cm) and diameter growth (0.3 cm), shoot (0.6 g) and root biomass accumulation (0.13 g), fruit weight (3 g), and shoot carbohydrate content (98 mg g-1), but lowest foliar acid phosphatase activity (30 µg NPP g-1 FW min-1). With the increase of SMS proportion in the substrate, the medium pH and electrical conductance (EC) increased with the decrease of foliar size. The available N and P contents in the substrates showed contrasting relationship with N and P contents in pepper plants. Therefore, fresh SMS cannot be directly used as the substrate for the culture of pepper plants. According to our findings fresh SMS was recommended to be mixed in the proportion of 25% with commercial peat for the culture of horticultural plants

Construction of an RNAi vector for knockdown of GM-ACS genes in the cotyledonary nodes of soybean

Background: Ethylene plays an important role in the regulation of floral organ development in soybean, and 1-aminocyclopropane-1-carboxylate synthase (ACS) is a rate-limiting enzyme for ethylene biosynthesis. However, whether ACS also regulates floral organ differentiation in soybean remains unknown. To address this, we constructed an RNAi vector to inhibit ACS expression in cotyledonary nodes. Linear DNA cassettes of RNAi-ACS obtained by PCR were used to transform soybean cotyledonary nodes. Results: In total, 131 of 139 transiently transformed plants acquired herbicide resistance and displayed GUS activities in the new buds. In comparison to untransformed seedling controls, a greater number of flower buds were differentiated at the cotyledonary node; GM-ACS1 mRNA expression levels and ethylene emission in the transformed buds were reduced. Conclusion: These results indicate that the cotyledonary node transient transformation system may be suitable for stable transformation and that the inhibition of ACS expression may be an effective strategy for promoting floral organ differentiation in soybean

Maintaining healthy sleep patterns and frailty transitions: a prospective Chinese study

Background: Little is known about the effects of maintaining healthy sleep patterns on frailty transitions. Methods: Based on 23,847 Chinese adults aged 30–79 in a prospective cohort study, we examined the associations between sleep patterns and frailty transitions. Healthy sleep patterns included sleep duration at 7 or 8 h/d, without insomnia disorder, and no snoring. Participants who persisted with a healthy sleep pattern in both surveys were defined as maintaining a healthy sleep pattern and scored one point. We used 27 phenotypes to construct a frailty index and defined three statuses: robust, prefrail, and frail. Frailty transitions were defined as the change of frailty status between the 2 surveys: improved, worsened, and remained. Log-binomial regression was used to calculate the prevalence ratio (PR) to assess the effect of sleep patterns on frailty transitions. Results: During a median follow-up of 8.0 years among 23,847 adults, 45.5% of robust participants, and 10.8% of prefrail participants worsened their frailty status, while 18.6% of prefrail participants improved. Among robust participants at baseline, individuals who maintained sleep duration of 7 or 8 h/ds, without insomnia disorder, and no-snoring were less likely to worsen their frailty status; the corresponding PRs (95% CIs) were 0.92 (0.89–0.96), 0.76 (0.74–0.77), and 0.85 (0.82–0.88), respectively. Similar results were observed among prefrail participants maintaining healthy sleep patterns. Maintaining healthy sleep duration and without snoring, also raised the probability of improving the frailty status; the corresponding PRs were 1.09 (1.00–1.18) and 1.42 (1.31–1.54), respectively. Besides, a dose-response relationship was observed between constantly healthy sleep scores and the risk of frailty transitions (P for trend Conclusions: Maintaining a comprehensive healthy sleep pattern was positively associated with a lower risk of worsening frailty status and a higher probability of improving frailty status among Chinese adults