University of Jordan

About: University of Jordan is a education organization based out in Amman, Jordan. It is known for research contribution in the topics: Population & Health care. The organization has 7796 authors who have published 13764 publications receiving 213526 citations.

Detection of sublethal thermal injury in Salmonella enterica serotype typhimurium and Listeria monocytogenes using Fourier transform infrared (FT-IR) spectroscopy (4000 to 600 cm(-1)).

Abstract: Fourier transform infrared (FT-IR) spectroscopy (4000 to 600 cm(-1)) was utilized to detect sublethally heat-injured microorganisms: Salmonella enterica serotype Typhimurium ATCC 14028, a Gram-negative bacterium, and Listeria monocytogenes ATCC 19113, a Gram-positive bacterium. A range of heat treatments (N= 2) at 60 degrees C were evaluated: 0D (control), 2D, 4D, 6D, and 8D using a D(60 degrees C) (S. enterica serotype Typhimurium ATCC 14028 = 0.30 min, L. monocytogenes ATCC 19113 = 0.43 min). The mechanism of cell injury appeared to be different for Gram-negative and Gram-positive microbes as observed from differences in the 2nd derivative transformations and loadings plot of bacterial spectra following heat treatment. The loadings for PC1 and PC2 confirmed that the amide I and amide II bands were the major contribution to spectral variation, with relatively small contributions from C-H deformations, the antisymmetric P==O stretching modes of the phosphodiester nucleic acid backbone, and the C-O-C stretching modes of polysaccharides. Using soft independent modeling of class analogy (SIMCA), the extent of injury could be predicted correctly at least 83% of the time. Partial least squares (PLS) calibration analysis was constructed using 5 latent variables for predicting the bacterial counts for survivors of the different heat treatments and yielded a high correlation coefficient (R= 0.97 [S. enterica serotype Typhimurium] and 0.98 [L. monocytogenes]) and a standard error of prediction (SEP= 0.51 [S. enterica serotype Typhimurium] and 0.39 log(10) CFU/mL [L. monocytogenes]), indicating that the degree of heat injury could be predicted.

Reversible thermosensitive biodegradable polymeric actuators based on confined crystallization.

Abstract: We discovered a new and unexpected effect of reversible actuation of ultrathin semicrystalline polymer films. The principle was demonstrated on the example of thin polycaprolactone-gelatin bilayer films. These films are unfolded at room temperature, fold at temperature above polycaprolactone melting point, and unfold again at room temperature. The actuation is based on reversible switching of the structure of the hydrophobic polymer (polycaprolactone) upon melting and crystallization. We hypothesize that the origin of this unexpected behavior is the orientation of polycaprolactone chains parallel to the surface of the film, which is retained even after melting and crystallization of the polymer or the "crystallization memory effect". In this way, the crystallization generates a directed force, which causes bending of the film. We used this effect for the design of new generation of fully biodegradable thermoresponsive polymeric actuators, which are highly desirable for bionano-technological applications such as reversible encapsulation of cells and design of swimmers.

Bayesian inference for the generalized exponential distribution

Abstract: The two-parameter generalized exponential (GE) distribution was introduced by Gupta and Kundu [Gupta, R.D. and Kundu, D., 1999, Generalized exponential distribution. Australian and New Zealand Journal of Statistics, 41(2), 173–188.]. It was observed that the GE can be used in situations where a skewed distribution for a nonnegative random variable is needed. In this article, the Bayesian estimation and prediction for the GE distribution, using informative priors, have been considered. Importance sampling is used to estimate the parameters, as well as the reliability function, and the Gibbs and Metropolis samplers data sets are used to predict the behavior of further observations from the distribution. Two data sets are used to illustrate the Bayesian procedure.

Selection of Barley Lines for Drought Tolerance in Low-Rainfall Areas

Abstract: An experiment was conducted at five locations in Jordan (Khanasri, annual rainfall 3 150 mm; Ramtha, 225 mm; Muwaqar, 150 mm; Rabba, 350 mm; Ghweer, 250 mm) during the 1996/1997 growing season, to evaluate the yield performance and some agronomic traits of 84 barley breeding lines and three long-term checks 4 (Zanbaka, Arta and Klaxon) for drought tolerance. An a-lattice design with two replications and six incomplete blocks for each replication was used. Genotype 6 (WI2291/Tadmor) was found to be superior in grain yield, especially compared to the best check (Arta) at the two wettest locations (Rabba and Ghweer). Genotype 21 (Mo.B1337/WI2291/5/ Emir/Sb//CM67/3/F8-HB-854-23/121//148-221/4/CI08887/ CI05761) out-yielded the best check (Arta) at the driest location (Khanasri), while genotype 61 (Salmas/Arabia Aswad) produced a higher grain yield than the best check (Zanbaka) at Ramtha. The correlations amongst grain yield, biological yield, straw yield, plant height and harvest index were always significant and positive regardless of the location. The correlations amongst days to heading, days to maturity and grain yield were significant at the two driest locations only. This suggests that diAerent phonologies are required to maximize grain yield in wet and dry environments. Also, the relationship between grain yield and the length of grain-filling period was positive in the wettest location (Rabba), negative in the driest (Khanasri) and not significant at the two intermediate locations. These results emphasize the importance of selection in the target environment and the need to develop early-maturing genotypes as a way of withstanding drought and high temperatures during the grain-filling period. A high and negative correlation coeAcient was found between the drought susceptibility index and grain yield at the driest site, whereas at the wettest site the correlation coeAcient was lower and in some cases positive, indicating the existence of traits that are desirable under drought and undesirable under favourable conditions.

Drought indices and indicators revisited

Abstract: There are numerous drought indicators used by decision makers all around the globe which have been developed to fulfill specific needs. By far, risks associated with drought and related consequences have become a bold topic for scientists in which debates still taking place everywhere. No global drought indices could provide universally accepted results since almost all of these indices are based on observed data as key performance indicators. In this respect, researchers spend a lot of effort on this issue for a better understanding on the various indices which are proposed until now. It is crucial to get a better sense on how drought can develop and how it can be monitored. It is also important to understand that, recent global challenges like climate change also amplifies the obligation on continues effort toward developing better indicators and methods to monitor droughts. As climate patterns change or a seasonal shift occurs, predefined drought indicators become useless. In this review, the concepts of drought indices and indicators are revisited and evaluated. Pros and cons of frequently used indices are addressed and the major differences between them are bolded. It is concluded that each index is applicable to fulfill expectations of a specific drought type while pre-knowledge about each case is very crucial. However, there is a need to develop a composite drought index to integrate all relevant data and drought definitions, with respect to the dominant types of monthly droughts in time and space together with climate change scenarios.