765 research outputs found

    On the generalized Hartley-Hilbert and Fourier-Hilbert transforms

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    In this paper, we discuss Hartley-Hilbert and Fourier-Hilbert transforms on a certain class of generalized functions. The extended transforms considered in this article are shown to be well-defined, one-to-one, linear and continuous mappings with respect to δ and Δ convergence. Certain theorems are also established

    Evaluation of the resistance of few citrus rootstocks to alkalinity by applying a faste test of secreening

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    Alkalinity of Moroccan soils is the major abiotic constraint on citrus production area. The best choice of citrus rootstocks adequate and resistant is a better solution to avoid this problem. The aim of this study is to develop a fast test of citrus rootstocks screening towards alkalinity. The alkaline stress was applied on ten citrus rootstocks two month old, using irrigation with a Hoagland and Arnon solution added with 1 g CaCO(3)/L and adjusted at various pH levels 6, 7 and 9. Observations concerned symptoms incidence and severity of iron chlorosis after two months of rearing. Results permitted to classify Poncirus trifoliata and Flying dragon as the most sensitive to alkalinity stresses, whereas, Citrus volkameriana and Citrus macrophylla were resistant. These conclusions are equivalent with those obtained with old citrus rootstocks in field trials

    Dielectric characteristics of spin-coated dielectric films using on-wafer parallel-plate capacitors at microwave frequencies

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    Includes bibliographical references.Dielectric properties of spin-coated dielectric insulators suitable for high-speed device fabrication are investigated. Complex dielectric permittivities and tangential losses of two polyimides, bisbenzocyclobutene (BCB), and a spin-on-glass (SOG) were extracted from the measured microwave reflection coefficient, S11, of parallel-plate capacitors over a frequency range of 50 MHz to 40 GHz. A model for the dielectric permittivity as a function of frequency is developed based on measured data with a minimum square error of less than 10-4 between measured and modeled microwave reflection coefficients. A circuit model for the pad capacitance is obtained based on geometrical and physical considerations. The relationship between the dielectric loss and its thickness is considered. Experimental results are fitted to Debye and Cole-Cole models.This work has been supported in part by the Defense Advanced Research Projects Agency under contract number DAAD19-03-1-0059 and by Yarmouk University in Irbid, Jordan

    Pregnant Women’s Malaria Knowledge in Ebonyi State, South-East Nigeria

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    The study aimed at investigating knowledge of malaria among pregnant women in Ebonyi state, South-east Nigeria. The cross-sectional survey research design was adopted in the study. Stratified sampling technique was used in selecting 504 pregnant women attending antenatal clinic in 12 hospitals in the state. A face validated, self constructed questionnaire which was subjected to a reliability test using Kuder Richardson Formula 20 (K-R 20) yielded a reliability value of 0.94. Percentages were used for analysis for the purpose of describing the data and chi-square statistic was used for the purpose of testing hypotheses. Results of the study showed that pregnant women had high (64.90%) level of knowledge regarding malaria. However, a good proportion of the pregnant women specifically had misconception about the cause of malaria and its mode of transmission. The pregnant women significantly differed in the knowledge of malaria with those having post secondary education (70.70%) showing better knowledge, followed by those with secondary (66.10%), primary (63.09%) and non-formal (55.70%) education. Location of residence was significantly associated with knowledge of malaria with those living in the urban area demonstrating better knowledge than those in the rural area. The high level of malaria knowledge among the women should be sustained through constant malaria health education interventions for pregnant women in the state. Intervention efforts should focus on rural pregnant women and formulated to accommodate the less educated members of this group as well as address misconceptions about the cause of malaria. Keywords: Malaria, Knowledge, Pregnant women, Ebonyi stat

    Combined effect of frustration and dimerization in ferrimagnetic chains and square lattice

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    Within the zero-temperature linear spin-wave theory we have investigated the effect of frustration and dimerization of a Heisenberg system with alternating spins s1s_{1} and s2s_{2} on one- and two-dimensional lattices. The combined effect most visibly appears in the elementary excitation spectra. In contrast to the ground state energy that decreases with dimerization and increases with frustration, the excitation energies are shown to be suppressed in energy by both dimerization and frustration. The threshold value of frustration that signals a transition from a classical ferrimagnetic state to a spiral state, decreases with dimerization, showing that dimerization further helps in the phase transition. The correlation length and sublattice magnetization decrease with both dimerization and frustration indicating the destruction of the long-range classical ferrimagnetic. The linear spin wave theory shows that in the case of a square lattice, dimerization initially opposes the frustration-led transition to a spiral magnetic state, but then higher magnitudes of lattice deformation facilitate the transition. It also shows that the transition to spiral state is inhibited in a square lattice beyond a certain value of dimerization.Comment: 8 pages, latex, 12 postscript figure

    Characterization of pharyngeal hypocontractility patterns during deglutition: High Resolution Impedance Manometry findings

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    Introduction High resolution impedance manometry (HRIM) provides an objective measure of pharyngeal pressurization and bolus flow and can be analysed using pressure flow analysis (PFA). The aim of the study is to investigate different types of pharyngeal hypocontractility and their distribution in patients with pharyngeal dysphagia. Material and Methods A cohort study was conducted on patients with dysphagia referred for HRIM. Inclusion criteria were abnormal (<5th percentile) pharyngeal contractile integral (PhCI) or abnormal regional contractile integrals (velo- or meso- or hypo-pharyngeal integrals). PFA was performed on 10ml liquid swallows using the Swallow GatewayTM open access analysis portal. Patients were classified based on a proposed HRIM scheme. The distribution of PFA metrics was compared between patients with normal and abnormal PhCI using the chi-squared test. Results In total 38 patients were studied and 137 swallows were analysed. Absent pharyngeal contractility was found in 5.3% (2/38) of the patients, ineffective pharyngeal contractility in 68.4% (26/38), and fragmented pharyngeal contractility in 26.3% (10/38). Regional weakness was mainly observed in the mesopharynx (94.7% of the patients), followed by the hypopharynx (50%) and the velopharynx (15.8%). A combined disorder of pharyngeal propulsion and UES restriction was seen in 44.7% (17/38) of the patients. Patients with a normal PhCI (fragmented pharyngeal contractility) were more likely to present an abnormal integrated relaxation pressure at the level of the upper esophageal sphincter (\u3c72=14.56, p=0.001) Conclusion Based on the pharyngeal contractile integrals, two main types of pharyngeal hypocontractility are present in the clinical population of patients: ineffective and fragmented pharyngeal contractility. Totally absent peristalsis in uncommon. In almost half of the patients, pharyngeal propulsion disorders are combined to disorders of UES restriction

    Single-crystal growth and dependences on the hole concentration and magnetic field of the magnetic ground state in the edge-sharing CuO2_2 chain system Ca2+x_{2+x}Y2x_{2-x}Cu5_5O10_{10}

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    We have succeeded in growing large-size single-crystals of Ca2+x_{2+x}Y2x_{2-x}Cu5_5O10_{10} with 0x1.670 \le x \le 1.67 and measured the magnetic susceptibility, specific heat and magnetization curve, in order to study the magnetic ground state in the edge-sharing CuO2_2 chain as a function of hole concentration and magnetic field. In 0x1.30 \le x \le 1.3, it has been found that an antiferromagnetically ordered phase with the magnetic easy axis along the b-axis is stabilized and that a spin-flop transition occurs by the application of magnetic fields parallel to the b-axis. The antiferromagnetic transition temperature decreases with increasing xx and disappears around x=x = 1.4. Alternatively, a spin-glass phase appears around x=1.5x = 1.5. At x=1.67x = 1.67 where the hole concentration is \sim 1/3 per Cu, it appears that a spin-gap state is formed owing to the formation of spin-singlet pairs. No sign of the coexistence of an antiferromagnetically ordered state and a spin-gap one suggested in Ca1x_{1-x}CuO2_2 has been found in Ca2+x_{2+x}Y2x_{2-x}Cu5_5O10_{10}.Comment: 13 pages, 12 figures, 1 tabl

    Characterization of esophageal motility and esophagogastric junction in preterm infants with bronchopulmonary dysplasia

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    Background: To characterize esophageal motility and function of the esophagogastric junction (EGJ) in preterm infants with bronchopulmonary dysplasia (BPD). Methods: High-resolution manometry with impedance was used to investigate esophageal motility and EGJ function in 28 tube-fed preterm infants with BPD. Patients with BPD were studied at term age during oral feeding. Thirteen healthy term-aged infants were included as controls. Esophageal analysis derived objective measures to evaluate esophageal contractile vigor, bolus distension pressure, EGJ relaxation, and EGJ barrier function (in rest and during respiration). In addition, we investigated the effect of BPD severity on these measures. Key results: A total of 140 nutritive swallows were analyzed (BPD, n = 92; controls, n = 48). Normal esophageal peristaltic wave patterns were observed in all infants. BPD patients had higher distal contractile esophageal strength compared with controls (Kruskal-Wallis (KW) P =.048), and their deglutitive EGJ relaxation was comparable to controls. Severe BPD patients showed higher bolus distension pressures, higher EGJ resting pressures, and increased EGJ contractile integrals compared with mild BPD patients (Mann-Whitney U P =.009, KW P =.012 and KW P =.028, respectively). Conclusions and Inferences: Preterm infants with BPD consistently present with normal peristaltic esophageal patterns following nutritive liquid swallows. The EGJ barrier tone and relaxation pressure appeared normal. In general, infants with BPD do not have altered esophageal motor function. There is however evidence for increased flow resistance at the EGJ in severe BPD patients possibly related to an increased contractility of the diaphragm
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