62 research outputs found

    Nanostructure Evolution of Magnetron Sputtered Hydrogenated Silicon Thin Films

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    Hydrogenated silicon (Si:H) thin films have been prepared by radio frequency (RF) magnetron sputtering. The effect of hydrogen gas concentration during sputtering on the resultant film structural and optical properties has been investigated by real time spectroscopic ellipsometry (RTSE) and grazing incidence x-ray diffraction (GIXRD). The analysis of in-situ RTSE data collected during sputter deposition tracks the evolution of surface roughness and film bulk layer thickness with time. Growth evolution diagrams depicting amorphous, nanocrystalline and mixed-phase regions for low and high deposition rate Si:H are constructed and the effects of process parameter (hydrogen gas concentration, total pressure and RF power) variations on the deposition rate have been qualified. Virtual interface analysis of RTSE data provides nanocrystalline volume fraction depth profiles in the mixed-phase growth regime. GIXRD measurements show the presence of (111) and (220) oriented crystallites. Vibrational mode absorption features from Si-Hn bonding configurations at 590, 640, 2000 and 2090 cm-1 are obtained by ex-situ infrared spectroscopic ellipsometry. Hydrogen incorporation decreases as films transition from amorphous to nanocrystalline phases with increasing hydrogen gas concentration during sputtering. Published by AIP Publishing

    Stealthy Backdoor Attack for Code Models

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    Code models, such as CodeBERT and CodeT5, offer general-purpose representations of code and play a vital role in supporting downstream automated software engineering tasks. Most recently, code models were revealed to be vulnerable to backdoor attacks. A code model that is backdoor-attacked can behave normally on clean examples but will produce pre-defined malicious outputs on examples injected with triggers that activate the backdoors. Existing backdoor attacks on code models use unstealthy and easy-to-detect triggers. This paper aims to investigate the vulnerability of code models with stealthy backdoor attacks. To this end, we propose AFRAIDOOR (Adversarial Feature as Adaptive Backdoor). AFRAIDOOR achieves stealthiness by leveraging adversarial perturbations to inject adaptive triggers into different inputs. We evaluate AFRAIDOOR on three widely adopted code models (CodeBERT, PLBART and CodeT5) and two downstream tasks (code summarization and method name prediction). We find that around 85% of adaptive triggers in AFRAIDOOR bypass the detection in the defense process. By contrast, only less than 12% of the triggers from previous work bypass the defense. When the defense method is not applied, both AFRAIDOOR and baselines have almost perfect attack success rates. However, once a defense is applied, the success rates of baselines decrease dramatically to 10.47% and 12.06%, while the success rate of AFRAIDOOR are 77.05% and 92.98% on the two tasks. Our finding exposes security weaknesses in code models under stealthy backdoor attacks and shows that the state-of-the-art defense method cannot provide sufficient protection. We call for more research efforts in understanding security threats to code models and developing more effective countermeasures.Comment: 18 pages, Under review of IEEE Transactions on Software Engineerin

    n-i-p Nanocrystalline Hydrogenated Silicon Solar Cells with RF-Magnetron Sputtered Absorbers

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    Nanocrystalline hydrogenated silicon (nc-Si:H) substrate configuration n-i-p solar cells have been fabricated on soda lime glass substrates with active absorber layers prepared by plasma enhanced chemical vapor deposition (PECVD) and radio frequency magnetron sputtering. The cells with nanocrystalline PECVD absorbers and an untextured back reflector serve as a baseline for comparison and have power conversion efficiency near 6%. By comparison, cells with sputtered absorbers achieved efficiencies of about 1%. Simulations of external quantum efficiency (EQE) are compared to experimental EQE to determine a carrier collection probability gradient with depth for the device with the sputtered i-layer absorber. This incomplete collection of carriers generated in the absorber is most pronounced in material near the n/i interface and is attributed to breaking vacuum between deposition of layers for the sputtered absorbers, possible low electronic quality of the nc-Si:H sputtered absorber, and damage at the n/i interface by over-deposition of the sputtered i-layer during device fabrication

    EFEK AIR REBUSAN KAYU CINA (Lannea coromandelica) TERHADAP HISTOPATOLOGI MUKOSA LAMBUNG MENCIT (Mus musculus) YANG DIINDUKSI ASAM KLORIDA (HCl)

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    Penelitian ini bertujuan untuk mengetahui efek air rebusan kayu cina terhadap histopatologi mukosa lambung mencit (mus musculus) yang diinduksi asam klorida (HCl). Penelitian ini menggunakan mencit jantan strain ICR sebanyak 45 ekor yang dibagi dalam 3 kelompok perlakuan, yaitu kelompok mencit normal, kelompok mencit gastritis, dan kelompok mencit dengan pemberian air rebusan kayu cina selama 7 dan 14 hari sebanyak 0.3 cc. Hasilnya menunjukkan bahwa setelah pemberian air rebusan kayu cina ada perbaikan sel-sel mukosa lambung mencit. Kesimpulan dalam penelitian ini adalah bahwa air rebusan kayu cina menunjukkan adanya perbaikan secara histopatologis mukosa lambung mencit yang diinduksi asam klorida (HCl)

    The effect of different substrates on oyster mushroom (Pleurotus ostreatus) spawn growth

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    The study aimed to find alternative substrates for growing spawn of oyster mushroom (Pleurotus ostreatus). The experiment was laid out in a completely randomized design with three compositions of substrates. The substrate compositions were: (1) Substrate A (corn 100%), (2) Substrate B (corn and sawdust mix in a ratio of (1:1, v/v)), and (3) Substrate C (corn and sawdust mix in a ratio of (3:1, v/v)). All compositions were replicated 18 times. The complete colonization (days) and mycelium growth rate (cm day-1) were recorded. Means were analyzed by Analysis of Variance (ANOVA) and duncan test was performed if there were significant between the substrate compositions. The results showed that substrate C was the best substrate indicated with the fastest complete colonization of 14.17±0.92 and the highest growth rate of 0.85±0.06 cm day-1

    TGF-β inhibitor Smad7 regulates dendritic cell-induced autoimmunity

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    TGF-β is an anti-inflammatory cytokine whose signaling is negatively controlled by Smad7. Previously, we established a role for Smad7 in the generation of autoreactive T cells; however, the function of Smad7 in dendritic cells (DCs) remains elusive. Here, we demonstrate that DC-specific Smad7 deficiency resulted in elevated expression of the transcription factors Batf3 and IRF8, leading to increased frequencies of CD8(+)CD103(+) DCs in the spleen. Furthermore, Smad7-deficient DCs expressed higher levels of indoleamine 2,3-dioxygenase (IDO), an enzyme associated with tolerance induction. Mice devoid of Smad7 specifically in DCs are resistant to the development of experimental autoimmune encephalomyelitis (EAE) as a result of an increase of protective regulatory T cells (Tregs) and reduction of encephalitogenic effector T cells in the central nervous system. In agreement, inhibition of IDO activity or depletion of Tregs restored disease susceptibility. Intriguingly, when Smad7-deficient DCs also lacked the IFN-γ receptor, the mice regained susceptibility to EAE, demonstrating that IFN-γ signaling in DCs mediates their tolerogenic function. Our data indicate that Smad7 expression governs splenic DC subset differentiation and is critical for the promotion of their efficient function in immunity

    Characterization of Actinomycetes Antagonist Fusariumoxysporum f.sp.passiflora Isolated from Rhizosphere Soil ofPurple Passion Fruit Plants, South Sulawesi, Indonesia

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    To survey rhizosphere actinomycetes as potential biocontrol against fungal diseaseof passion fruits, rhizosphere soil of the plant were used as an isolation sources. Twenty fivestrains were assigned to Streptomyces-like strain based on morphological properties of sporechain. Four strain with distinguishing characteristic based on the macroscopic appearance ofcolonies on different media, were recovery from rhizosphere soil of passion fruits plantsuggesting that various Streptomyces spp. grow surrounding of plant roots. On an agarmedium, four strains (11.43%) commonly formed a clear growth-inhibition zone against fungal pathogen of passion fruits, Fusarium oxysporum f.sp. radicalix passiflori (FORP), indicatingthat this strains can produce antifungal substances. The present results indicate that four strainare a suitable candidate for the biocontrol of fusarium wilt. Keywords: Actinomycetes, AntifungalFusarium oxysporum f.sp.passiflora Rhizosphere, Purple Passion Fruit Plants, South Sulawesi, Indonesi

    Simultaneously Hermaphroditic Shrimp Use Lipophilic Cuticular Hydrocarbons as Contact Sex Pheromones

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    Successful mating is essentially a consequence of making the right choices at the correct time. Animals use specific strategies to gain information about a potential mate, which is then applied to decision-making processes. Amongst the many informative signals, odor cues such as sex pheromones play important ecological roles in coordinating mating behavior, enabling mate and kin recognition, qualifying mate choice, and preventing gene exchange among individuals from different populations and species. Despite overwhelming behavioral evidence, the chemical identity of most cues used in aquatic organisms remains unknown and their impact and omnipresence have not been fully recognized. In many crustaceans, including lobsters and shrimps, reproduction happens through a cascade of events ranging from initial attraction to formation of a mating pair eventually leading to mating. We examined the hypothesis that contact pheromones on the female body surface of the hermaphroditic shrimp Lysmata boggessi are of lipophilic nature, and resemble insect cuticular hydrocarbon contact cues. Via chemical analyses and behavioural assays, we show that newly molted euhermaphrodite-phase shrimp contain a bouquet of odor compounds. Of these, (Z)-9-octadecenamide is the key odor with hexadecanamide and methyl linoleate enhancing the bioactivity of the pheromone blend. Our results show that in aquatic systems lipophilic, cuticular hydrocarbon contact sex pheromones exist; this raises questions on how hydrocarbon contact signals evolved and how widespread these are in the marine environment

    Existencia y unicidad de solución y comportamiento asintótico para la ecuación de onda con condición de frontera del tipo Neumann y disipación localmente distribuido

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    En este trabajo se estudia la existencia y unicidad de solución de la ecuación de la onda con condiciones de frontera del tipo Neumann, con disipación localmente distribuida usando el método de Faedo Galerkin. Además analiza el decaimiento no exponencial de la energía asociado al sistema planteado. Se hacen las estimativas correspondientes basándose en propiedades del espacio donde se encuentra la solución de la ecuación, así como los teoremas correspondientes al sistema estudiado.Tesi
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