398 research outputs found
Peptide Ligands that Interact with Newcastle Disease Virus: Selection, Characterization and Applications
Newcastle disease, a highly contagious disease of the avian species is
caused by the Newcastle disease virus (NOV). In Malaysia there have been 29
outbreaks of NOV reported this year alone. In spite of the availability of mass
vaccination programmes, these sporadic outbreaks are believed to be the result
of malpractice in backyard farming. The mechanism of NOV infection is still not
clearly understood, making it difficult to validate any effective drug candidates.
Bearing this in mind, a phage display random peptide library was used to identify
peptide ligands that interact with NOV. A phage carrying the TLTTKLY sequence
represented 97% of the total phage screened from the third round of biopanning
against NOV strain AF2240. This phage was characterized and both cyclic and
linear synthetic peptides bearing the homologous sequence were synthesized
Drop Axis Ratio Distributions in Stratiform and Convective Rain
A fully calibrated low profile 2D video disdrometer (2DVD) has been recording many different rainfall events in Northern Alabama (USA) since June 2007. An earlier publication reported drop shapes and axis ratio distributions determined for some of the events. For one of the cases examined, a noticeable shift in the 3.5 - 3.75 mm drop axis ratio distribution was noted. In this paper, we extend the earlier work by separating the 2DVD measurements into stratiform and convective rain. The separation is made possible by using the minute-by-minute drop size distribution (DSD) measured by the 2DVD. The 1-minute DSDs are fitted to a gamma distribution, and using a simple indexing technique which involves two of the fitted parameters, periods of convective and stratiform rain are separated for a given event. The output of the DSD indexing technique is qualitatively confirmed by comparing with simultaneous time series observations from a co-located UHF profiler which continuously records height profiles of reflectivity, Doppler mean and spectral width, all of which enable the identification of bright-band periods and, furthermore, periods of moderate and deep convection. Excellent consistency is found between the output of the DSD-based separation method and the profiler observations. Next, we utilize the output of DSD index-based separation method to flag the periods of severe convection for a given event. Drop axis ratios during the flagged periods are derived and compared with those during stratiform rain periods. Five cases have been considered. Axis ratio distributions do not show appreciable differences between stratiform and convective periods for four of the cases. The fifth case (the same case as reported earlier) shows a shift in the 3.5 - 3.75 mm drop axis ratios during a prolonged period of convection. The contoured shapes for these drops determined from the 2DVD camera data indicate the possibility of non-axisymmetric oscillations, compared with the contoured images for other events which fit well to our reference drop shapes. For all of above cases, observations from a C-band polarimetric radar - situated 15 km away are examined. The variations between the co-polar radar reflectivity and the differential reflectivity as well as the specific differential phase are compared with the 2DVD data based scattering calculations for the 5 events. The implications will be discussed
DSD Characteristics of a Mid-Winter Tornadic Storm Using C-Band Polarimetric Radar and Two 2D-Video Disdrometers
Drop size distributions in an evolving tornadic storm are examined using C-band polarimetric radar observations and two 2D-video disdrometers. The E-F2 storm occurred in mid-winter (21 January 2010) in northern Alabama, USA, and caused widespread damage. The evolution of the storm occurred within the C-band radar coverage and moreover, several minutes prior to touch down, the storm passed over a site where several disdrometers including two 2D video disdrometers (2DVD) had been installed. One of the 2DVDs is a low profile unit and the other is a new next generation compact unit currently undergoing performance evaluation. Analyses of the radar data indicate that the main region of precipitation should be treated as a "big-drop" regime case. Even the measured differential reflectivity values (i.e. without attenuation correction) were as high as 6-7 dB within regions of high reflectivity. Standard attenuation-correction methods using differential propagation phase have been "fine tuned" to be applicable to the "big drop" regime. The corrected reflectivity and differential reflectivity data are combined with the co-polar correlation coefficient and specific differential phase to determine the mass-weighted mean diameter, Dm, and the width of the mass spectrum, (sigma)M, as well as the intercept parameter , Nw. Significant areas of high Dm (3-4 mm) were retrieved within the main precipitation areas of the tornadic storm. The "big drop" regime assumption is substantiated by the two sets of 2DVD measurements. The Dm values calculated from 1-minute drop size distributions reached nearly 4 mm, whilst the maximum drop diameters were over 6 mm. The fall velocity measurements from the 2DVD indicate almost all hydrometeors to be fully melted at ground level. Drop shapes for this event are also being investigated from the 2DVD camera data
Very Large Rain Drops from 2D Video Disdrometers and Concomitant Polarimetric Radar Observations
Drop size distribution (DSD) measurements using ground-based disdrometers (point measurements) have often been used to derive equations to relate radar observations to the integral rainfall parameters (Atlas et al. 1999, Bringi et al., 2003, Kozu et al., 2006, Tokay and Short, 1996, Ajayi and Owolabi, 1987, Battan, 1973). Disdrometers such as JWD, MRR and several others have a major limitation in measuring drops with equi-volume diameters (D(sub eq)) larger than 5 mm because they often rely on the velocity-diameter relationship which plateaus beyond this diameter range (Atlas et al., 1973, Gunn & Kinzer, 1949). Other disdrometers such as Parsivel also lack accuracy beyond this diameter range. The 2D video disdrometer (2DVD: Schnhuber et al., 2008) on the other hand gives drop-shape contours and velocities for each individual drop/hydrometeor falling through its sensor area; this provides a unique opportunity to study the role of very-large drops on radar measurements in particular those with polarimetric radar capability where DSDs with a significant component of very large drops may require special consideration given that the differential reflectivity and other polarimetric radar parameters including attenuation-correction methods will be sensitive to the concentrations of these large drops. A recent study on the occurrence of large drops by Gatlin et al. (2014) has compiled a large and diverse set of measurements made with the 2D video disdrometers from many locations around the globe. Some of the largest drops found in this study were 9 mm D(sub eq) and larger, and in this paper, we report on three such events, with maximum D(sub eq's) of 9.0, 9.1 and 9.7 mm, which occurred in Colorado, Northern Alabama, and Oklahoma, respectively. Detailed examination of the 2DVD data - in terms of shapes and fall velocities - has confirmed that these are fully-melted hydrometeors, although for the last case in Oklahoma, a bigger and non-fully-melted hydrometeor was also observed. All three events were also captured by polarimetric radars, namely the S-band CHILL radar operated by Colorado State University (Brunkow et al., 2000), the C-band ARMOR radar (Petersen et al., 2007) operated by University of Alabama in Huntsville, and NEXRADKVNX, operated by the US National Weather Service, respectively. For the last event, several other radar observations were also made, including two X-band radars operated by the US Dept. of Energy. Analyses of 2DVD data in conjunction with the corresponding radar observations are presented, along with some discussion on sampling issues related to the measurements of such large rain drops. The latter is addressed using maximum diameter D(sub max) measurements from 1-minute DSDs using two collocated 2DVDs for 37 events in Huntsville
Relationship between Bioethanol Production and Agricultural Commodity Prices: for the case of Thailand
This paper examines the relationship between bio-ethanol production and agricultural commodity prices in Thailand. The main feedstocks for producing bioethanol in Thailand are sugarcane, cane molasses and cassava. Monthly data has been used from January 2006 to March 2014 to conduct this research. The existence of long-run relationships among the four variables i.e. bioethanol production, sugarcane farm gate price, cane molasses export price and cassava farm gate price detected through the Auto Regressive Distributive Lag (ARDL) framework. Then, the Granger Causality Test (Wald Test) used to investigate the short-run causal relationship among those variables. From the result found that when bioethanol production act as independent variable, long-run equilibrium exist between bioethanol production and sugarcane farm gate price, cane molasses export price and cassava farm gate price, respectively. Besides that, Granger causality exists among the variables as well. Sugarcane farm gate price and bioethanol production as well as cassava farm gate price and bioethanol production are found to be having unidirectional Granger causality effect. Meanwhile, bidirectional Granger causality effect is found between cane molasses export price and bioethanol production. The results of this study would contribute towards significant policy making in Thailand
Drop size distribution comparisons between Parsivel and 2-D video disdrometers
Measurements from a 2-D video disdrometer (2DVD) have been
used for drop size distribution (DSD) comparisons with co-located Parsivel
measurements in Huntsville, Alabama. The comparisons were made in terms of
the mass-weighted mean diameter, <i>D</i><sub>m</sub>, the standard deviation of the
mass-spectrum, <i>σ</i><sub>m</sub>, and the rainfall rate, <i>R</i>, all based on
1-min DSD from the two instruments. Time series comparisons show close
agreement in all three parameters for cases where <i>R</i> was less than 20 mm h<sup>−1</sup>.
In four cases, discrepancies in all three parameters were seen for "heavy"
events, with the Parsivel showing higher <i>D</i><sub>m</sub>, <i>σ</i><sub>m</sub> and <i>R</i>,
when <i>R</i> reached high values (particularly above 30 mm h<sup>−1</sup>). Possible causes for
the discrepancies include the presence of a small percentage of non-fully
melted hydrometers, with higher than expected fall velocity and with very
different axis ratios as compared with rain, indicating small hail or ice
pellets or graupel. We also present here Parsivel-to-Parsivel comparisons as
well as comparisons between two 2DVD instruments, namely a low-profile unit
and the latest generation, "compact unit" which was installed at the same
site in November 2009. The comparisons are included to assess the variability
between the same types of instrument. Correlation coefficients and the
fractional standard errors are compared
Observing the Full Spectrum of the Rain Drop Size Distribution
GPM DSD retrievals exhibit inconsistencies between GV, DPR and Combined algorithm retrievals. Development of positive bias in convective Dm rain DSD noted, and strongest in KuPR retrieval. Associated epsilons are too low and result in markedly reduced convective rain rates (a current issue in the retrievals). Source may be NUBF. Issues with the large end of the DSD not withstanding, on the small end of the DSD, combined MPS and 2DVD measurements fit with generalized gamma functions exhibit strong potential for representing the entire spectrum of the DSD and subsequently the whole rain rate spectrum
The influence of safety climate on safety performance among workers of a food emulsifiers company in Malaysia
This study aimed to determine the relationship between safety climate and safety performance in Danisco Malaysia Sdn. Bhd. Six dimensions of safety climate were studied in this research namely management safety practices, safety attitude, safety training, supervisory safety practices, the involvement of co-workers, and job safety. In order to achieve the objectives of the study, 146 sets of questionnaires were distributed to the staff in the operation department of Danisco Malaysia. Quantitative data were analyzed using SPSS software. Pearson correlation test found a significant positive relationship for five out of six dimensions of safety climate against with safety performance. The five significant dimensions are management safety practices, safety training, supervisory safety practices, the involvement of co-workers, and job safety. However, safety attitude was found to have an insignificant relationship with safety performance. Multiple regression tests revealed that safety climate dimensions significantly influence safety performance. Finally, the implications of the study are discussed to provide recommendations and guidelines for future researches
Drop Shapes Versus Fall Velocities in Rain: 2 Contrasting Examples
Rainfall retrievals from polarimetric radar measurements require the knowledge of four fundamental rain microstructure parameters, namely, drop size distribution, drop shape distribution, canting angles and drop fall velocities. Some recent measurements of all four parameters in natural rain are summarized in [1]. In this paper, we perform an in-depth analysis of two events, using two co-located 2D video disdrometers (2DVD; see [2]) both with high calibration accuracy, and a C-band polarimetric radar [3], located 15 km away. The two events, which occurred 7 days apart (on the 18th and the 25th of Dec 2009), had moderate-to-intense rainfall rates, but the second event had an embedded convection line within the storm. The line had passed over the 2DVD site, thus enabling the shapes and fall velocities to be determined as the line crossed the site. The first event was also captured in a similar manner by both the 2DVDs as well as the C-band radar. Drop fall velocity measurements for, say, the 3 mm drops show noticeable differences between the two events. Whereas for the first event, the velocity distribution showed a narrow and symmetric distribution, with a mode at the expected value (7.95 m/s, as given by the formula in [4]), the second event produced a wider distribution with a significant skewness towards lower velocities (although its mode too was close to the expected value). Moreover, the slower 3 mm drops in the second event occurred when the convection line was directly over the 2DVD site (03:35-03:45 utc), and not before nor after. A similar trend was observed in terms of the horizontal dimensions of the 3 mm drops, i.e. large fluctuations during the same time period, but not outside the period. Vertical dimensions of the drops also fluctuated but not to the same extent. Interestingly, the horizontal dimensions tended towards larger values during the 10-minute period, implying an increase in drop oblateness, which in turn indicates the possibility of the horizontal mode oscillation, one of the three fundamental modes of drop oscillations [5], albeit the most difficult one to excite
Consistent Measurement and Physical Character of the DSD: Disdrometer to Satellite
Objective: Validate GPM (Global Precipitation Measurement) Drop Size Distribution Retrievals: Drop size distributions (DSD) are critical to GPM DPR (Dual-frequency Precipitation Radar)-based rainfall retrievals; NASA GPM Science Requirements stipulate that the GPM Core observatory radar estimation of D (sub m) (mean diameter) shall be within plus or minus 0.5 millimeters of GV (Ground Validation); GV translates disdrometer measurements to polarimetric radar-based DSD and precipitation type retrievals (e.g., convective vs. stratiform (C/S)) for coincident match-up to GPM core overpasses; How well do we meet the requirement across product versions, rain types (e.g., C/S partitioning), and rain rates (heavy, light) and is behavior physically and internally consistent
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