Weak Signal Strength Research Articles

The earliest excipient products of Traditional Chinese Medicine: Identification and analysis of samples from wooden lacquer box unearthed from Haihunhou tomb in the Western Han Dynasty

The processing of traditional Chinese medicine is an integral part of Chinese medical heritage. The recent discovery of the earliest processed drugs may provide strong evidence for the origins of traditional Chinese medicine processing. The remains were found in wooden lacquer boxes, unearthed from Haihunhou tomb in Nanchang, Jiangxi Province. By analyzing the appearance of the unearthed samples, it was found that the outer layers of the samples were composed of an auxiliary material and the inside was composed of plant material. As can be seen from the three-dimensional image taken using nuclear magnetic resonance screening, the sample had a hollow irregular rod structure. The outer layers were composed of a substance with weak signal strength, and the inside was similar to the fiber structure of plants with high water contents. Microscopic analysis showed that periderm, secondary xylem, and broad wood rays could be seen in the transverse section of the plants inside the samples. It can be further speculated that the plants inside the samples were derived from the roots or stems of dicotyledonous herbs. Additionally, the putative roots or stems of the dicotyledonous herbs had secondary structures and contained one to three clustered, red-brown cells. No starch granules, calcium oxalate crystals, or stone cells were observed in the transverse section. According to the microscopic database of the National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, it is speculated that the plants inside the samples were derived from the roots of Rehmannia species. A comparative study of the microscopic characteristics of wild Rehmannia chingii roots and the unearthed samples was carried out. It was found that both displayed periderm, broad secondary phloem, wood rays, similar vessel morphologies, and red-brown cells. The unearthed samples and R. chingii roots were analyzed by electrospray ionization mass spectrometry (ESI-MS) in negative ion mode. The results showed that the mass spectrum peak of m / z 623 in the unearthed samples agreed with that in the roots of R. chingii , and was putatively identified as acteoside or forsythiaside. Moreover, the peak at m / z 179 in the unearthed samples was identified as caffeic acid based on the molecular weight using high resolution tandem mass spectrometry (MS/MS) data, and was usually identified as a hydrolysate of acteoside or forsythiaside. There were about two to three outer layers of excipient on the samples. They were distributed unevenly, thicker at the top and thinner at the bottom. The plants and excipient layers were observed by microscope, and starch grains were found in the cross section and powder of the excipient layers, while no starch grains were found in the cross section or powder of the plant material inside. However, the reaction between the plant tissues and iodine-potassium iodide test solution produced the characteristic blue color. This phenomenon was related to the gelatinization of starch granules. Under a polarized light microscope, a large number of crystals were seen in the excipient layers. An aqueous extract of the excipient layers was analyzed by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS), and an ion fragment peak at m / z 341.11 was detected, indicating a disaccharide. When compared to the reference substances glucose, sucrose, fructose, and maltose, the retention times and mass spectra were very similar to that of sucrose. According to ancient literary and historical records, the tomb owner suffered from severe rheumatism before his death, which is consistent with the efficacy of R. chingii . It is further speculated that the samples in the wooden lacquer boxes are the remains of processed ancient traditional Chinese medicine products. The origin of the excipients in the processed medicines might be related to improving the taste, which could provide a scientific basis for further understanding the processing and application of ancient traditional Chinese medicines.

New Method for Positioning Using IRIDIUM Satellite Signals of Opportunity

The global navigation satellite system (GNSS) system has a number of disadvantages such as weak signal strength and high cost, while signals of opportunity (SOPs) can make up for these shortcomings. Non-GNSS satellite SOPs offer some advantages in terms of high signal strength, low cost that belongs to ground-based SOPs and better coverage than ground-based SOPs. We investigate a new method of instantaneous Doppler positioning with Iridium signals that are treated as satellite SOPs. Initially, the Iridium SOPs positioning system is introduced through a description of its characteristics and components. Next, the instantaneous Doppler positioning algorithm is introduced, and the effects of measurement errors and satellite orbital errors on the positioning solution are analyzed by a new method. Furthermore, the influence of constellation geometrical distribution on positioning performance is analyzed based on the relative position relationship between discrete distribution points of the receiver position. Finally, the simulation data are used for theoretical verification, and the real data experiment is implemented with IRIDIUM NEXT signals. The results show that the two-dimensional (2-D) position accuracies of approximately 22 m ($1\sigma$ ) can be achieved with the height aiding when the static receiver has a complete view of the sky.

UAV Hovering Strategy Based on a Wirelessly Powered Communication Network

With the development of wireless power transfer technology, wirelessly powered communication networks (WPCNs), which can provide a sustainable energy supply for the user equipment, have received extensive attention from researchers. An unmanned aerial vehicle (UAV)-based WPCN (U-WPCN) can effectively solve the problems of energy shortage and weak signal strength for ground terminals in remote areas. To establish a highly efficient U-WPCN, the service area for each UAV platform should be determined such that each UAV platform will hover at the optimal position according to the locations of the ground terminals in its group. Through hovering position optimization, this paper proposes two networking strategies for improving networking efficiency and maximizing communication performance. A greedy algorithm is used to find the optimal hovering point for each area; thus, the hovering points of all UAVs in the U-WPCN are finally obtained. Simulation results show that the UAV utilization efficiency can be significantly increased through the economical mode, and the terminal transmission rates can be improved for a given number of drones in the performance mode.

Quantitative EMCD by use of a double aperture for simultaneous acquisition of EELS

The weak signal strength in electron magnetic circular dichroism (EMCD) measurements remains one of the main challenges in the quantification of EMCD related EELS spectra. As a consequence, small variations in peak intensity caused by changes of background intervals, choice of method for extraction of signal intensity and equally differences in sample quality can cause strong changes in the EMCD signal. When aiming for high resolution quantitative EMCD, an additional difficulty consists in the fact that the two angular resolved EELS spectra needed to obtain the EMCD signal are taken at two different instances and it cannot be guaranteed that the acquisition conditions for these two spectra are identical. Here, we present an experimental setup where we use a double hole aperture in the transmission electron microscope to obtain the EMCD signal in a single acquisition. This geometry allows for the parallel acquisition of the two electron energy loss spectra (EELS) under exactly the same conditions. We also compare the double aperture acquisition mode with the qE acquisition mode which has been previously used for parallel acquisition of EMCD. We show that the double aperture mode not only offers better signal to noise ratio as compared to qE mode but also allows for much higher acquisition times to significantly improve the signal quality which is crucial for quantitative analysis of the magnetic moments.

Improving Library User Experience: Wi-Fi Network Assessment

Librarians have been seeking solutions to improve library user experience. The popularity of mobile devices leads to the increasing demand for reliable and efficient wireless communication in libraries. The City Tech librarians make an effort to improve Wi-Fi network to address such challenge. The Wi-Fi survey results indicate that students are dissatisfied with the library Wi-Fi access and hope to get better wireless communication for their mobile devices. To seek approaches to the improvement of Wi-Fi speed and reliability, the authors adopted NetSpot Pro loaded with the library building map to audit wireless network performance. The Wi-Fi site survey shows the library Wi-Fi network has not only weak Wi-Fi signal strength, but also experiences severe interference and overlapping channels. The study suggests that the Library and campus IT can enhance the Wi-Fi network performance by adding more wireless APs and optimizing the locations of existing APs, Wi-Fi network setting, and wireless connection procedure. By upgrading the CUNY Fiber Network and network improvement strategy, the Library can provide effective wireless communication for student learning and research, and ultimately give students memorable library experiences.

Bi-directional equalization for long-range underwater acoustic communication in East Sea of Korea

The long-range underwater acoustic communications using a sound channel in deep sea have been studied for many years. The acoustic waves transmitted through the sound channel can be propagated by long distance because there is no interaction with the sea surface and bottom interfaces. However, the transmitted signals are distorted by multipath propagation. Time reversal combining followed by a single channel equalizer can reduce efficiently the effects of multipath communication channel and thus increases signal-to-noise ratio by obtaining temporal and spatial diversity. However, the conventional time reversal tends to increase the entire error rate when burst errors occur. Long-range communication signals are particularly vulnerable to burst errors due to the weak signal strength. In this talk, the bi-directional equalization is applied to compensate for the distortion of long-range communication signals where the burst errors occur. Since the bi-directional equalization combines the soft outputs of forward and backward equalization, the effect of error propagation due to burst error can be reduced. The long-range communication experiment data acquired in the East Sea of Korea in October 1999 is used to verify the performance of the bi-directional equalization. The results show that the bi-directional equalization can be effectively applied when burst errors exist. [Work supported by the ADD(UD170022DD) and the National Research Foundation of Korea (NRF-2016R1D1A1B03930983).]

TJS-2 geostationary satellite orbit determination using onboard GPS measurements

This study analyzes the quality of onboard data of tracking signals from GPS satellites on the far side of the earth and determines the orbit of the geostationary satellite using code and carrier phase observations with 30-h and 3-day orbit arc length. According to the analysis results, the onboard receiver can track 6–8 GPS satellites, and the minimum and maximum carrier to noise spectral densities were 24 and 45 dB-Hz, respectively. For a GPS receiver on a high-altitude platform above the navigation constellations, the blocking of the earth and a weak signal strength usually cause a piece-wise GPS signal tracking and an increase in the number of ambiguity parameters. Individual GPS satellites may be continuously tracked for as little as several minutes and as long as 3 h. Moreover, considering the negative sign of elevation angles reflects the fact that GPS satellites are tracked below the receiver in the study. GPS satellites appear mainly in the elevation angle range of − 53° to − 83°, and dilution of precision values could reach ten or one hundred and more. Also, it is observed that when a signal suffers from atmospheric refraction, other GPS signals tracked simultaneously by the receiver experience strong systematic errors in the code observations. Based on single-frequency code and carrier phase measurements, the mean 3D root mean square (RMS) value of the overlap comparisons between 30-h orbit determination arcs is 2.14 m. However, we found that there were also some biases in the carrier phase residuals, which contributed to poor orbit accuracy. To eliminate the effects of the biases, we established a correction sequence for each GPS satellite. After corrections, the mean 3D RMS was reduced to 0.99 m, representing a 53% improvement.

A Preliminary Assessment of Hyperspectral Remote Sensing Technology for Mapping Submerged Aquatic Vegetation in the Upper Delaware River National Parks (USA)

Hyperspectral remote sensing of submerged aquatic vegetation is a complex and difficult process that is affected by unique constraints on the energy flow profile near and below the water surface. In addition, shallow, winding, lotic systems, such as the Upper Delaware River, present additional remote sensing problems in the form of specular reflectance, variable depth and constituents in the water column and sometimes extremely weak signal strength due to absorption and scattering in the water column that can be statistically overwhelmed by the reflectance from upland vegetation in any individual image scene. Here we test hyperspectral imagery from the Civil Air Patrol’s (CAP), Airborne Real-time Cueing Hyperspectral Enhanced Recon (ARCHER) system in the scenic waters of two National Parks on the Upper Delaware River. A number of unique image processing problems were encountered, including specular reflectance from winding lotic systems, variable depth and flow dynamics of the riverine environment, and disproportionate signal strength from surface reflectance in this riverine environment. These problems were solved by applying a specular reflectance removal algorithm, applying field data collections to classification results and masking upland vegetation so as to not statistically overwhelm the weak reflectance signal from surface and near-surface water. Much was learned about conducting imaging spectroscopy in such difficult conditions. Important results include successful mapping of Submerged Aquatic Vegetation (SAV) presence/absence, advantages of upland masking of the reflectance signal, and a number of processing approaches that are unique to this environment. In this paper we summarize our results and identify unique issues that must be addressed in this environment.

Generalized GNSS Signal Carrier Tracking—Part II: Optimization and Implementation

This paper presents the performance analysis and the optimizations of the generalized phase locked loop (PLL) and the generalized frequency locked loop (FLL). Using the minimum mean square error (MMSE) criterion as a performance measure, the optimal solutions for the generalized PLL and FLL designs under various scenarios: strong and weak signal strength, low and high dynamic, and good and poor oscillator quality are investigated. An adaptive PLL based on automatically adjustment of the integration time and loop parameters in an optimized manner is proposed. An adaptive FLL that operates with the optimal loop parameters is also presented. Simulation results demonstrate the effectiveness of the proposed generalized closed-loop tracking architecture and validate the proposed adaptive tracking schemes.

IgH isotype-specific B cell receptor dosage regulates B cell fate

Abstract Immunoglobulin heavy chain (IgH) isotypes (e.g. IgM, IgG and IgE) are generated as secreted/soluble antibodies (sIg) or as membrane-bound (mIg) B cell receptors (BCR) through alternative RNA splicing. IgH isotype dictates soluble antibody function, but how mIg isotype influences B cell behavior is unclear. We examined IgH isotype-specific BCR function by engineering polyclonal Ighγ1/γ1 and Ighɛ/ɛ mice, which initially produce IgG1 or IgE from their respective native genomic configurations. Transcripts producing IgM, IgG1, and IgE are produced in an alternative splice form bias hierarchy, where mIgμ>mIgγ1>mIgɛ—influencing respective BCR densities and fitness for populating the periphery—a pattern replicated in activated and memory B cells from wild-type mice. Restrained B cell development from Ighγ1/γ1 and Ighɛ/ɛ mice was proportional to sIg/mIg ratios, and was rescued by enforced expression of the respective mIgs. In addition, enhanced BCR signaling by way of PTEN deletion in IgE B cells generated functional IgE memory responses from IgE memory B cells themselves, which are normally absent under normal conditions, indicating that weak signal strength normally restrains IgE responses. Thus, IgH isotype-specific mIg dosage regulates B cell fate by influencing quantitative baseline BCR signal strength.

지상 송신원 항공 전자 탐사 1차원 모델링

Airborne transient electromagnetic (ATEM) surveying was introduced several decades ago in the mining industry to detect shallow conductive targets. However, conventional ATEM systems have limited depth of investigation because of weak signal strength. Recently, the grounded electrical source airborne transient electromagnetic (GREATEM) system was proposed to increase the depth of investigation. The GREATEM is a semi-airborne transient electromagnetic system because a long grounded wire is used as the transmitter. Traditionally, ATEM sounding data have been interpreted with 1D earth models to save the computing time because modern ATEM systems generally collect large data sets. However, the GREATEM 1D modeling requires numerical integration along the wire, so it takes much more time than the 1D modeling of conventional ATEM. In this study, the adaptive Born forward mapping (ABFM) was applied to the ATEM 1D modeling because the ABFM is incommensurably faster than the ordinary GREATEM 1D modeling. Comparing the results from ordinary and ABFM 1D modeling, it was confirmed that the ABFM can be applied to the 1D modeling of GEATEM.

Effect of Signal Intensity on Measurement of Ganglion Cell Complex and Retinal Nerve Fiber Layer Scans in Fourier-Domain Optical Coherence Tomography.

We determined the effect of Fourier-domain optical coherence tomography (OCT) signal strength index (SSI) and cropping on retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) scan repeatability and measurement thickness. Eyes were enrolled in the longitudinal Advanced Imaging for Glaucoma Study. At each visit, three repeat scans from the optic nerve head and macular protocols were obtained. Each measurement was associated with an SSI value from 0 to 100. Measurements with similar SSI scores were grouped to calculate repeatability defined as pooled standard deviation. Within-visit analysis was used to determine how measured thickness changed in relation to change in SSI level. The study included 1130 eyes of 569 patients. Cropped images yielded significantly worse repeatability and they were excluded from subsequent analyses. The within-visit repeatability for RNFL and GCC measurements were significantly better with higher signal strength, and optimal cutoffs were SSI ≥ 37 and ≥ 44, respectively. The coefficient of variation was <1.8% for RNFL scans with SSI ≥ 37 and < 2% for GCC with SSI ≥ 44. For scans above the cutoff SSI, higher SSI's were correlated with thicker RNFL among normal (slope = 0.056 μm/SSI unit, P < 0.001) eyes and glaucoma suspect and perimetric glaucoma (GSPPG) eyes (slope = 0.060 μm/SSI unit, P < 0.001), but not for perimetric glaucoma (PG) eyes. No significant correlation was found for GCC. Repeatability of RNFL and GCC thickness measurements may be improved by excluding images with cropped anatomic features and weak signal strength below recommended SSI cutoffs. Measurement precision and image quality of inner eye structure by advanced imaging modality are important for clinical diagnosis and tracking of glaucoma disease.

Performance of the High Sensitivity Open Source Multi-GNSS Assisted GNSS Reference Server.

AbstractThe Open Source GNSS Reference Server (OSGRS) exploits the GNSS Reference Interface Protocol (GRIP) to provide assistance data to GPS receivers. Assistance can be in terms of signal acquisition and in the processing of the measurement data. The data transfer protocol is based on Extensible Mark-up Language (XML) schema. The first version of the OSGRS required a direct hardware connection to a GPS device to acquire the data necessary to generate the appropriate assistance. Scenarios of interest for the OSGRS users are weak signal strength indoors, obstructed outdoors or heavy multipath environments.This paper describes an improved version of OSGRS that provides alternative assistance support from a number of Global Navigation Satellite Systems (GNSS). The underlying protocol to transfer GNSS assistance data from global casters is the Networked Transport of RTCM (Radio Technical Commission for Maritime Services) over Internet Protocol (NTRIP), and/or the RINEX (Receiver Independent Exchange) format. This expands the assistance and support model of the OSGRS to globally available GNSS data servers connected via internet casters. A variety of formats and versions of RINEX and RTCM streams become available, which strengthens the assistance provisioning capability of the OSGRS platform.The prime motivation for this work was to enhance the system architecture of the OSGRS to take advantage of globally available GNSS data sources. Open source software architectures and assistance models provide acquisition and data processing assistance for GNSS receivers operating in weak signal environments. This paper describes test scenarios to benchmark the OSGRSv2 performance against other Assisted-GNSS solutions. Benchmarking devices include the SPOT satellite messenger, MS-Based &amp; MS-Assisted GNSS, HSGNSS (SiRFstar-III) and Wireless Sensor Networks Assisted-GNSS. Benchmarked parameters include the number of tracked satellites, the Time to Fix First (TTFF), navigation availability and accuracy.Three different configurations of Multi-GNSS assistance servers were used, namely Cloud-Client-Server, the Demilitarized Zone (DMZ) Client-Server and PC-Client-Server; with respect to the connectivity location of client and server. The impact on the performance based on server and/or client initiation, hardware capability, network latency, processing delay and computation times with their storage, scalability, processing and load sharing capabilities, were analysed.The performance of the OSGRS is compared against commercial GNSS, Assisted-GNSS and WSN-enabled GNSS devices. The OSGRS system demonstrated lower TTFF and higher availability.

A Packet-Interleaving Scheme Using RS Code for Burst Errors in Wireless Sensor Networks

In this paper, we propose a packet-interleaving scheme (PIS) for increasing packet reliability under burst errors in wireless sensor networks (WSN). In a WSN, packet errors could occur due to weak signal strength or interference. These erroneous packets have to be retransmitted, which will increase network load substantially. The proposed PIS, encoding data using Reed-Solomon (RS) codes, can classify data into two different types: high-reliability-required (HRR) data and non-HRR data. An HRR packet is encoded with a short RS symbol, while a non-HRR packet with a long RS symbol. When an HRR and a non-HRR packet arrive at a sensor, they are interleaved on a symbol-by-symbol basis. Thus, the effect of burst errors (BE) is dispersed and consequently the uncorrectable HRR packets can be reduced. For the purpose of evaluation, two models, the uniform bit-error model (UBEM) and the on-off bit-error model (OBEM), are built to analyze the packet uncorrectable probability. In the evaluation, we first change the lengths of BE, then we vary the shift positions in a BE period, and finally we increase the number of correctable symbols to observe the superiority of the proposed PIS in reducing packet uncorrectable probability.

Aircraft Evaluation of Ground-Based Raman Lidar Water Vapor Turbulence Profiles in Convective Mixed Layers

AbstractHigh temporal and vertical resolution water vapor measurements by Raman and differential absorption lidar systems have been used to characterize the turbulent fluctuations in the water vapor mixing ratio field in convective mixed layers. Since daytime Raman lidar measurements are inherently noisy (due to solar background and weak signal strengths), the analysis approach needs to quantify and remove the contribution of the instrument noise in order to derive the desired atmospheric water vapor mixing ratio variance and skewness profiles. This is done using the approach outlined by Lenschow et al.; however, an intercomparison with in situ observations was not performed.Water vapor measurements were made by a diode laser hygrometer flown on a Twin Otter aircraft during the Routine Atmospheric Radiation Measurement (ARM) Program Aerial Facility Clouds with Low Optical Water Depths Optical Radiative Observations (RACORO) field campaign over the ARM Southern Great Plains (SGP) site in 2009. Two days with Twin Otter flights were identified where the convective mixed layer was quasi stationary, and hence the 10-s, 75-m data from the SGP Raman lidar could be analyzed to provide profiles of water vapor mixing ratio variance and skewness. Airborne water vapor observations measured during level flight legs were compared to the Raman lidar data, demonstrating good agreement in both variance and skewness. The results also illustrate the challenges of comparing a point sensor making measurements over time to a moving platform making similar measurements horizontally.

Constraining the black hole mass spectrum with gravitational wave observations - II. Direct comparison of detailed models

A number of scenarios have been proposed for the origin of the supermassive black holes (SMBHs) that are found in the centres of most galaxies. Many such scenarios predict a high-redshift population of massive black holes (MBHs), with masses in the range 100 to 100000 times that of the Sun. When the Laser Interferometer Space Antenna (LISA) is finally operational, it is likely that it will detect on the order of 100 of these MBH binaries as they merge. The differences between proposed population models produce appreciable effects in the portion of the population which is detectable by LISA, so it is likely that the LISA observations will allow us to place constraints on them. However, gravitational wave detectors such as LISA will not be able to detect all such mergers nor assign precise black hole parameters to the merger, due to weak gravitational wave signal strengths. This paper explores LISA's ability to distinguish between several MBH population models. In this way, we go beyond predicting a LISA observed population and consider the extent to which LISA observations could inform astrophysical modellers. The errors in LISA parameter estimation are applied with a direct method which generates random sample parameters for each source in a population realisation. We consider how the distinguishability varies depending on the choice of source parameters (1 or 2 parameters chosen from masses, redshift or spins) used to characterise the model distributions, with confidence levels determined by 1 and 2-dimensional tests based on the Kolmogorov-Smirnov test.

Essential Role for Mir-181a1/b1 In T-Cell Acute Lymphoblastic Leukemia

AbstractAbstract 470MiRNA-mediated gene regulation represents a fundamental layer of post-transcriptional control of gene expression with diverse functional roles in normal development and tumorigenesis. Whereas some studies have shown that over-expression of miRNA genes may contribute to cancer development and progression, it is yet to be rigorously tested by the loss-of-function genetic approaches whether miRNA genes are required for cancer development and maintenance in mice. Here we show that mir-181a1/b1 coordinates Notch and pre-TCR signals during normal thymocyte differentiation and plays an essential role in development and onset of T-cell acute lymphoblastic leukemia (T-ALL) induced by some Notch mutations. Using gain-of-function and loss-of-function approaches, we demonstrated that mir-181a1/b1 controls Notch and pre-TCR receptor signals during the early stages of T cell development in the thymus by repressing multiple negative regulators of both pathways, including Nrarp, PTPN-22, SHP2, DUSP5, and DUSP6. These results illustrate that a single miRNA can coordinate multiple signaling pathways by modulating the timing and strength of signaling at different stages. Intriguingly, synergistic signaling between Notch and pre-TCR pathways is necessary for the development of T-ALL, and miR-181 family miRNAs are aberrantly expressed in T-ALL patients. These observations raise the possibility that mir-181a1/b1 might contribute to the onset or maintenance of T-ALL by targeting similar pathways in tumor cells as it does in normal thymic progenitor cells. In support of this notion, we found that loss of mir-181a1/b1 significantly delayed the onset and development of T-ALL induced by intracellular domain of Notch1 (ICN1) and caused a 32% increase in the median survival time from 41 days to 54 days in T-ALL mice. Importantly, we noted that loss of mir-181a1/b1 more efficiently repressed the leukemogeneic potential of cells with lower levels of ICN1 expression, suggesting that mir-181a1/b1 may be more effective in inhibiting T-ALL development induced by a Notch mutant with weaker signal strength. Indeed, we demonstrated that loss of mir-181a1b1 essentially blocked T-ALL development induced by the weaker Notch mutant and dramatically decreased mortality from 60% to 10% in these T-ALL mice. Since human Notch mutations identified in T-ALL patients generally have weaker signaling strength and lower oncogenic potential than that of ICN1, our findings indicate that mir-181a1/b1 may play an essential role in development of normal thymic progenitors and Notch-induced T-ALL and may be targeted to treat T-ALL patients harboring Notch mutations. Disclosures:No relevant conflicts of interest to declare.

Xanthan/chitosan gold chip for metal enhanced protein biomarker detection

Protein microarrays for disease diagnostics are required to accurately quantify analytes in the low pg/mL range. This task is hampered by weak signal strengths and too low detector sensitivity. Herein we present reflective gold chips coated with polyelectrolyte multilayers (PEMs) for signal enhancement in immunoassays for melanoma-relevant biomarkers. Among tested (semi)natural polysaccharides (xanthan, chitosan, carboxymethylcellulose, hyaluronic acid) PEMs composed of xanthan and chitosan performed best in terms of detection of low analyte concentrations (ED10), spot morphology, fluorescence background and variability (<10%). Fluorescence signals on gold slides with a 75 nm coating of seven crosslinked polyelectrolyte double layers were up to 50 times higher than on bare glass slides. In comparison to commercial substrates the signal to noise ratio is enhanced by up to factor 11. Furthermore sandwich assays for interleukins 6, 8, 10, tumour necrosis factor alpha (TNFα), vascular endothelial growth factor A (VEGF-A) and S100B show working ranges which cover significantly lower concentrations (up to 38-fold). Not limited to above assays the presented substrates, which combine a biocompatible interface with metal-based signal amplification, are a valuable tool in a variety of biosensor applications.

Constraining the black hole mass spectrum with gravitational wave observations - I. The error kernel

Many scenarios have been proposed for the origin of the supermassive black holes (SMBHs) that are found in the centres of most galaxies. Many of these formation scenarios predict a high-redshift population of intermediate-mass black holes (IMBHs), with masses in the range 100 to 100000 times that of the Sun. A powerful way to observe these IMBHs is via gravitational waves the black holes emit as they merge. The statistics of the observed black hole population should, in principle, allow us to discriminate between competing astrophysical scenarios for the origin and formation of SMBHs. However, gravitational wave detectors such as LISA will not be able to detect all such mergers nor assign precise black hole parameters to the merger, due to weak gravitational wave signal strengths. In order to use LISA observations to infer the statistics of the underlying population, these errors must be taken into account. We describe here a method for folding the LISA gravitational wave parameter error estimates into an `error kernel' designed for use at the population model level. The effects of this error function are demonstrated by applying it to several recent models of black hole mergers, and some tentative conclusions are made about LISA's ability to test scenarios of the origin and formation of supermassive black holes.

Electromagnetic Interference Immunity Testing of Medical Equipment to Second- and Third-Generation Mobile Phones

There has been concern regarding the effect of electromagnetic interference (EMI) on medical equipment from portable wireless communication devices in hospitals in Hong Kong. The latest third-generation (3G) mobile communication system was fully implemented in 2004. As a result, an investigation to examine the EMI issues surrounding medical equipment, due to interference from communication devices, including GSM900, PCS1800, and 3G digital mobile phones, has been carried out. A statistical analysis has shown that the cumulative distribution function of base station signals within the hospital's environment follows the Weibull distribution for all three mobile phone systems in Hong Kong and that the percentage of failed medical equipment increases with a correlation of an increase in the radiated power level of the mobile phone. This is a direct result of a weakening in base station signals. The EMI effect from 3G mobile phones is also found to be four to eight times lower than that of the GSM900 and PCS1800, in locations inside the hospitals with weak base station signal strength, such as a basement or in operation theaters.