Satellite estimates of wide-range suspended sediment concentrations in Changjiang (Yangtze) estuary using MERIS data

The Changjiang (Yangtze) estuarine and coastal waters are characterized by suspended sediments over a wide range of concentrations from 20 to 2,500 mg l-1. Suspended sediment plays important roles in the estuarine and coastal system and environment. Previous algorithms for satellite estimates of suspended sediment concentration (SSC) showed a great limitation in that only low to moderate concentrations (up to 50 mg l-1) could be reliably estimated. In this study, we developed a semi-empirical radiative transfer (SERT) model with physically based empirical coefficients to estimate SSC from MERIS data over turbid waters with a much wider range of SSC. The model was based on the Kubelka–Munk two-stream approximation of radiative transfer theory and calibrated using datasets from in situ measurements and outdoor controlled tank experiments. The results show that the sensitivity and saturation level of remote-sensing reflectance to SSC are dependent on wavelengths and SSC levels. Therefore, the SERT model, coupled with a multi-conditional algorithm scheme adapted to satellite retrieval of wide-range SSC, was proposed. Results suggest that this method is more effective and accurate in the estimation of SSC over turbid water

Cryptanalysis of an MPEG-Video Encryption Scheme Based on Secret Huffman Tables

This paper studies the security of a recently-proposed MPEG-video encryption scheme based on secret Huffman tables. Our cryptanalysis shows that: 1) the key space of the encryption scheme is not sufficiently large against divide-and-conquer (DAC) attack and known-plaintext attack; 2) it is possible to decrypt a cipher-video with a partially-known key, thus dramatically reducing the complexity of the DAC brute-force attack in some cases; 3) its security against the chosen-plaintext attack is very weak. Some experimental results are included to support the cryptanalytic results with a brief discuss on how to improve this MPEG-video encryption scheme.Comment: 8 pages, 4 figure

THE NUMBER OF SPHALERON INSTABILITIES OF THE BARTNIK-McKINNON SOLITONS AND NON-ABELIAN BLACK HOLES

It is proven that there are precisely $n$ odd-parity sphaleron-like unstable modes of the $n$-th Bartnik-McKinnon soliton and the $n$-th non-abelian black hole solution of the Einstein-Yang-Mills theory for the gauge group $SU(2)$.Comment: one reference is adde

Domain-swapped T cell receptors improve the safety of TCR gene therapy

T cells engineered to express a tumor-specific {alpha}{beta} T cell receptor (TCR) mediate anti-tumor immunity. However, mispairing of the therapeutic {alpha}{beta} chains with endogenous {alpha}{beta} chains reduces therapeutic TCR surface expression and generates self-reactive TCRs. We report a general strategy to prevent TCR mispairing: swapping constant domains between the {alpha} and {beta} chains of a therapeutic TCR. When paired, domain-swapped (ds)TCRs assemble with CD3, express on the cell surface, and mediate antigen-specific T cell responses. By contrast, dsTCR chains mispaired with endogenous chains cannot properly assemble with CD3 or signal, preventing autoimmunity. We validate this approach in cell-based assays and in a mouse model of TCR gene transfer-induced graft-versus-host disease. We also validate a related approach whereby replacement of {alpha}{beta} TCR domains with corresponding {gamma}{delta} TCR domains yields a functional TCR that does not mispair. This work enables the design of safer TCR gene therapies for cancer immunotherapy

New Critical Behavior in Einstein-Yang-Mills Collapse

We extend the investigation of the gravitational collapse of a spherically symmetric Yang-Mills field in Einstein gravity and show that, within the black hole regime, a new kind of critical behavior arises which separates black holes formed via Type I collapse from black holes formed through Type II collapse. Further, we provide evidence that these new attracting critical solutions are in fact the previously discovered colored black holes with a single unstable mode.Comment: 13 pages, 4 figure

Analysis of long-term terrestrial water storage variations in the Yangtze River basin

In this study, we analyze 32 yr of terrestrial water storage (TWS) data obtained from the Interim Reanalysis Data (ERA-Interim) and Noah model from the Global Land Data Assimilation System (GLDAS-Noah) for the period 1979 to 2010. The accuracy of these datasets is validated using 26 yr (1979–2004) of runoff data from the Yichang gauging station and comparing them with 32 yr of independent precipitation data obtained from the Global Precipitation Climatology Centre Full Data Reanalysis Version 6 (GPCC) and NOAA's PRECipitation REConstruction over Land (PREC/L). Spatial and temporal analysis of the TWS data shows that TWS in the Yangtze River basin has decreased significantly since the year 1998. The driest period in the basin occurred between 2005 and 2010, and particularly in the middle and lower Yangtze reaches. The TWS figures changed abruptly to persistently high negative anomalies in the middle and lower Yangtze reaches in 2004. The year 2006 is identified as major inflection point, at which the system starts exhibiting a persistent decrease in TWS. Comparing these TWS trends with independent precipitation datasets shows that the recent decrease in TWS can be attributed mainly to a decrease in the amount of precipitation. Our findings are based on observations and modeling datasets and confirm previous results based on gauging station datasets

Micromechanical actuators for insect flight mechanics

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.Includes bibliographical references (p. 95-97).This project aims to develop MEMS actuators to aid in the study of insect flight mechanics. Specifically, we are developing actuators that can stimulate the antennae of the crepuscular hawk moth Manduca Sexta. The possible mechanosensory function of antennae as airflow sensors has been suggested, and recent discoveries of our collaborators reveal that mechanosensory input from the antennae of flying moths serves a similar role to that of the hind wings of two-winged insects, detecting Coriolis forces and thereby mediating flight stability during maneuvers. Early evidence suggests that mechanical stimulus of the antennae may enable flight control. In addition, the crepuscular hawk moth Manduca Sexta has a wide wingspan (~110 mm) and is capable of carrying at least one quarter of its own weight. Thus, studying the flight of Manduca Sexta by attachment of microsystems seems plausible. The goal of our project is to design and fabricate micromechanical actuators, which will be mounted onto the moth antennae. Our collaborators will study the flight control mechanism by mechanical stimulation. Our first step was to fabricate "dummy" silicon rings for our biologist collaborators for implant experiment. A series of mounting kits were developed, and due to the nature of the moth antennae, ring-beam-ring construction was finally designed and fabricated, like a "shackle", to meet the mounting requirements. Next, we integrated actuators onto the mounting kit. Piezoelectric film/sheet, piezoelectricbender and piezoelectric-stack were considered as the actuators. Live testing was also taken while the moth was resting or flapping its wings. The moth apparently responds to the mechanical stimulus under both circumstances, by swinging its wings and abdomen. Actuation amplifier was also modeled and tested, which might be used for future mechanical stimulators.by Hui Zhou.S.M

Human papillomavirus 16 L2 inhibits the transcriptional activation function, but not the DNA replication function, of HPV-16 E2

In this study we analysed the outcome of the interaction between HPV-16 L2 and E2 on the transactivation and DNA replication functions of E2. When E2 was expressed on its own, it transactivated a number of E2-responsive promoters but co-expression of L2 led to the down-regulation of the transcription transactivation activity of the E2 protein. This repression is not mediated by an increased degradation of the E2 protein. In contrast, the expression of L2 had no effect on the ability of E2 to activate DNA replication in association with the viral replication factor E1. Deletion mutagenesis identified L2 domains responsible for binding to E2 (first 50 N-terminus amino acid residues) and down-regulating its transactivation function (residues 301–400). The results demonstrate that L2 selectively inhibits the transcriptional activation property of E2 and that there is a direct interaction between the two proteins, although this is not sufficient to mediate the transcriptional repression. The consequences of the L2–E2 interaction for the viral life cycle are discussed

Superconductivity in the Nb2SnC compound

Nb2SnC is a member of the large family of lamellar materials that crystallize in the hexagonal structure with space group P63/mmc which are isomorphs with Cr2AlC, also named H-phase. In spite of the great number of compounds which belong to this family, the superconductivity has been reported only for two cases: Mo2GaC and Nb2SC. In this work we show that superconductivity can be observed in Nb2SnC depending on the synthesis method used. The quality of the superconductor is strongly dependent of the synthesis method and the optimal results were reached for samples synthesized at 2.5 GPa and 523 +/- 50oC. This sample showed a critical temperature close to 7.8K, revealed from magnetization and transport measurement, the highest critical temperature reported up to now for an H-phase.Comment: paper with 12 pages and 4 figure