Fast-Light in a Photorefractive Crystal for Gravitational Wave Detection

We demonstrate superluminal light propagation using two frequency multiplexed pump beams to produce a gain doublet in a photorefractive crystal of Ce:BaTiO3. The two gain lines are obtained by two-wave mixing between a probe field and two individual pump fields. The angular frequencies of the pumps are symmetrically tuned from the frequency of the probe. The frequency difference between the pumps corresponds to the separation of the two gain lines; as it increases, the crystal gradually converts from normal dispersion without detuning to an anomalously dispersive medium. The time advance is measured as 0.28 sec for a pulse propagating through a medium with a 2Hz gain separation, compared to the same pulse propagating through empty space. We also demonstrate directly anomalous dispersion profile using a modfied experimental configuration. Finally, we discuss how anomalous dispersion produced this way in a faster photorefractive crystal (such as SPS: Sn2P2S6) could be employed to enhance the sensitivity-bandwidth product of a LIGO type gravitational wave detector augmented by a White Light Cavity.Comment: 14 pages, 5 figure

Physical Electronics and Surface Physics

Contains reports on one research project.Joint Services Electronics Program (Contract DAAB07-74-C-0630

Use of microphysical relationships to discern growth/decay mechanisms of cloud droplets with focus on Z-LWC relationships.

Cloud droplet size distributions hence the key microphysical quantities (e.g., radar reflectivity, droplet concentration, liquid water content, relative dispersion, and mean-volume radius) are determined by different physical mechanisms, including pre-cloud aerosols as CCNs, cloud updraft, and various turbulent entrainment-mixing processes. Therefore, different relationships among these microphysical properties are expected in response to these various mechanisms. The effect of turbulent entrainment-mixing processes is particularly vexing, with different entrainment-mixing processes likely leading to different microphysical relationships. Cloud radar has been widely used to infer the cloud liquid water content (L) from the measurement of radar reflectivity (Z) using a Z-L relationship. Existing Z-L expressions have been often obtained empirically, and differ substantially (Khain et al. 2008). The discrepancy among Z-L relations, which has been hindering the application of cloud radar in measuring cloud properties, likely stems from the different relationships between the relevant microphysical properties caused by different physical processes. This study first analyzes the Z-L relationship theoretically, and identify the key microphysical properties that affect this relationship, and then address the effects of various processes on the Z-L relationship by discerning the characteristics of the relationships between the relative dispersion, droplet concentration, liquid water content, and mean-volume radius calculated from in-situ measurements of cloud droplet size distributions. Effort is also made to further relate the microphysical relationships to physical processes such as turbulent entrainment-mixing

Thienothiophene-benzotriazole-based semicrystalline linear copolymers for organic field effect transistors

A series of thienothiophene-benzotriazole-based semicrystalline copolymers, PTTBTz, PTTBTz-F, and PTTBTz-OR, were synthesized by considering chain linearity, planarity and inter-chain packing by virtue of non-covalent attractive interaction. Fluorine and alkoxy substituents were introduced to modulate the intra- and inter-chain coulombic interactions and crystalline ordering. The fluorine and alkoxy-substituted PTTBTz-F and PTTBTz-OR showed pronounced inter-chain packing with edge-on orientation confirmed by UV-vis absorption and X-ray diffraction measurements. The well-resolved diffraction patterns were obtained for PTTBTz-F and PTTBTz-OR, showing (100)similar to(500) inter-lamellar scattering peaks (d-spacing, 17 similar to 18 angstrom) in the out-of-plane direction and a pi-pi stacking peak (d-spacing, 3.5 similar to 4.1 angstrom) in the in-plane direction. Organic field effect transistor (OFET) devices were fabricated with a bottom gate and top contact geometry. PTTBTz-F (mu(h) = 4.49 x 10(-2) cm(2) V-1 s(-1), on/off ratio = 1.13 x 107) and PTTBTz-OR (mu(h) = 8.39 x 10(-3) cm(2) V-1 s(-1), on/off ratio = 2.98 x 104) showed nearly 3 and 2 orders of magnitude higher hole mobility upon annealing at 305 and 260 degrees C, with compared to the unsubstituted PTTBTz.X1165Ysciescopu

Suggestions of Principles to Reduce the Deviation of Steep Slope Evaluation Results through On-Site Evaluation

Geup Kyung Sa Ji (GGSJ) is the term used to refer to steep slopes managed by the Ministry of Interior and Safety (MOIS). The MOIS is a government agency of South Korea in charge of administration and safety, with evaluations and management carried out by local governments. There are 16,071 GGSJs as of March 2022. However, it is difficult to determine whether the evaluation results for these GGSJs are reliable and whether data are managed efficiently. Unlike the Ministry of Land, Infrastructure and Transport and the Korea Forest Service, there are personnel in charge of the relevant administration and welfare operations who are not experts in GGSJs. Therefore, a method for evaluating the currently managed steep slopes and the problems that arise in the process must be identified through evaluation by experts and non-experts in the field. Additionally, methods to increase the consistency and reliability of evaluation results must be determined. This study proposes methods designed to solve the problem of differences in evaluation results caused by the diversity of perspectives on the evaluation of GGSJs and which can be used in the assessment of complex slopes. This study aims to increase the efficiency and consistency of evaluation results in the integrated management of GGSJs to build trust among management staff

Anti-fibrotic effects of Rhus javanica Linn (Anacardiaceae) extract against Activated hepatic stellate cells via regulation of TGF-beta and smad signaling

Purpose: To evaluate the anti-fibrotic effects of ethanol extract of Rhus javanica Linn. (Anacardiaceae) (RJE) in activated hepatic stellate cells (HSCs) as well as explore the underlying mechanisms.Methods: The cytotoxic effect of RJE (100, 300 and 500 μg/mL) was analyzed using 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) assay in Chang liver cells. The mRNA expression of collagen type I, alpha 2 (COL1A2), transforming growth factor-beta (TGF-β), α-smooth muscle actin (α-SMA) and platelet-derived growth factor (PDGF) were determined using reverse transcription-polymerase chain reaction (RT-PCR) in HSCs. Protein expression of collagen and Smad were measured by Western blot analysis.Results: Treatment with RJE extract at 100, 300 and 500 μg/mL did not show any signs of cytotoxicity to Chang liver cells. RJE at 500 μg/mL concentration influenced the morphology, reduced the stretched fiber and  decreased the number of viable cells in activated HSCs. The increased expressional levels of fibrosis mediators such as COL1A2, TGF-β, α-SMA were decreased by RJE (500 μg/mL) pre-treatment. Quantification data showed that the increased band intensity of COL1A2 (1.41 ± 0.08), TGF-β (1.23 ± 0.13), α-SMA (1.71 ± 0.14) were significantly (p < 0.05) reduced to 0.39 ± 0.12, 0.35 ± 0.11 and 0.04 ± 0.08, respectively upon RJE treatment. However, RJE did not suppress the expression of PDGF gene. Mechanistic study revealed that RJE prevented fibrosis in HSCs via regulation of TGF-β and Smad signaling pathways.Conclusion: The findings show that RJE inhibits fibrosis production in HSCs and can be developed as a novel therapy for hepatic fibrosis. This is the first report showing the beneficial effects of R. javanica as an anti-fibrotic agent