Enhancement of Persistent Currents by Hubbard Interactions In Disordered 1D Rings: Avoided Level Crossings Interpretation

We study effects of local electron interactions on the persistent current of one dimensional disordered rings. For different realizations of disorder we compute the current as a function of Aharonov-Bohm flux to zeroth and first orders in the Hubbard interaction. We find that the persistent current is {\em enhanced} by onsite interactions. Using an avoided level crossings approach, we derive analytic formulas which explain the numerical results at weak disorder. The same approach also explains the opposite effect (suppression) found for spinless fermion models with intersite interactions.Comment: uuencoded: 17 pages, text in revtex, 7 figs in postscrip

Dome C site testing: surface layer, free atmosphere seeing and isoplanatic angle statistics

This paper analyses 3.5 years of site testing data obtained at Dome C, Antarctica, based on measurements obtained with three DIMMs located at three different elevations. Basic statistics of the seeing and the isoplanatic angle are given, as well as the characteristic time of temporal fluctuations of these two parameters, which we found to around 30 minutes at 8 m. The 3 DIMMs are exploited as a profiler of the surface layer, and provide a robust estimation of its statistical properties. It appears to have a very sharp upper limit (less than 1 m). The fraction of time spent by each telescope above the top of the surface layer permits us to deduce a median height of between 23 m and 27 m. The comparison of the different data sets led us to infer the statistical properties of the free atmosphere seeing, with a median value of 0.36 arcsec. The C_n^2 profile inside the surface layer is also deduced from the seeing data obtained during the fraction of time spent by the 3 telescopes inside this turbulence. Statistically, the surface layer, except during the 3-month summer season, contributes to 95 percent of the total turbulence from the surface level, thus confirming the exceptional quality of the site above it

Geology, geochemistry and are characteristics of the Jordanian phosphates

Abstract Jordan is situated on the northwestern side of the Arabian Plate, along the eastern flank of the ancient Tethys Ocean on the western side of the Dead Sea Transform. The country hosts huge phosphate deposits. The deposits at Eshidiya are comprised of overburden, four phosphate beds (A0, Al, A2 and A3), a coquina/marl waste bed, and two silicified phosphate chert interwaste beds. Eshidiya ore beds are treated separately through beneficiation and upgrading, as they produce products of different grade; they are subdivided into three classes. A 65% TCP (tricalcium phosphate) sub-commercial product is also produced. The detrimental impurities are considered to be among the lowest in the world. Chemical analyses of major oxides, organic matter and some traces in the product, which indicate almost similar chemical signature, are discussed herein

Middle East respiratory syndrome coronavirus in pediatrics: a report of seven cases from Saudi Arabia

This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.Infection with Middle East respiratory syndrome coronavirus (MERS-CoV) emerged in 2012 as an important respiratory disease with high fatality rates of 40%–60%. Despite the increased number of cases over subsequent years, the number of pediatric cases remained low. A review of studies conducted from June 2012 to April 19, 2016 reported 31 pediatric MERS-CoV cases. In this paper, we present the clinical and laboratory features of seven patients with pediatric MERS. Five patients had no underlying medical illnesses, and three patients were asymptomatic. Of the seven cases, four (57%) patients sought medical advice within 1–7 days from the onset of symptoms. The three other patients (43%) were asymptomatic and were in contact with patients with confirmed diagnosis of MERS-CoV. The most common presenting symptoms were fever (57%), cough (14%), shortness of breath (14%), vomiting (28%), and diarrhea (28%). Two (28.6%) patients had platelet counts of < 150 × 109/L, and one patient had an underlying end-stage renal disease. The remaining patients presented with normal blood count, liver function, and urea and creatinine levels. The documented MERS-CoV Ct values were 32–38 for four of the seven cases. Two patients (28.6%) had abnormal chest radiographic findings of bilateral infiltration. One patient (14.3%) required ventilator support, and two patients (28.6%) required oxygen supplementation. All the seven patients were discharged without complications

The Effect of Using Metacognitive Monitoring Strategy on Developing Reading Comprehension in English Language among Tenth Grade Students in North Eastern Badiah Directorate of Education

This study aimed at exploring the effect of using metacognitive monitoring strategy on developing reading comprehension in English language among tenth grade students in North Eastern Badiah directorate of education. The study used the quasi experimental design.The sample of the study consisted of 123 male and female students who were purposefully chosen from the tenth grade students at Alkaum Alahmer comprehensive secondary school for girls, Alkaum Alahmer comprehensive secondary school for boys, Um Aljemal comprehensive secondary school for girls and Um Aljemal comprehensive secondary school for boys. The experimental and control groups were assigned randomly. The groups of the study were found equivalent upon analyzing students\u27 scores on reading comprehension test using 2-way ANCOVA. The experimental groups were instructed using metacognitive monitoring program whereas, students of the control group were taught in the conventional way. A jury of judges was invited to comment on the reading test and the instructional program to establish their validity. At the end of the program, the researcher administered the reading comprehension test. Means and standard deviation for students\u27 scores on the reading comprehension test were calculated. Then 2- way ANCOVA was calculated to examine the effect of the strategy. The findings of the study revealed that there were statistically significant differences at (α =0.05) between students\u27 total achievement of the experimental groups and the control groups in the reading comprehension in favor of the experimental group and that there was no interaction between the use of metacognitive monitoring strategy and gender on tenth grade students\u27 reading comprehension. In the light of the findings, the researcher suggested some recommendations to The Ministry of Education and TEFL educators