Vibration-enhanced quantum transport

In this paper, we study the role of collective vibrational motion in the phenomenon of electronic energy transfer (EET) along a chain of coupled electronic dipoles with varying excitation frequencies. Previous experimental work on EET in conjugated polymer samples has suggested that the common structural framework of the macromolecule introduces correlations in the energy gap fluctuations which cause coherent EET. Inspired by these results, we present a simple model in which a driven nanomechanical resonator mode modulates the excitation energy of coupled quantum dots and find that this can indeed lead to an enhancement in the transport of excitations across the quantum network. Disorder of the on-site energies is a key requirement for this to occur. We also show that in this solid state system phase information is partially retained in the transfer process, as experimentally demonstrated in conjugated polymer samples. Consequently, this mechanism of vibration enhanced quantum transport might find applications in quantum information transfer of qubit states or entanglement.Comment: 7 pages, 6 figures, new material, included references, final published versio

Quantum transport in quantum networks and photosynthetic complexes at the steady state

Recently, several works have analysed the efficiency of photosynthetic complexes in a transient scenario and how that efficiency is affected by environmental noise. Here, following a quantum master equation approach, we study the energy and excitation transport in fully connected networks both in general and in the particular case of the Fenna-Matthew-Olson complex. The analysis is carried out for the steady state of the system where the excitation energy is constantly "flowing" through the system. Steady state transport scenarios are particularly relevant if the evolution of the quantum system is not conditioned on the arrival of individual excitations. By adding dephasing to the system, we analyse the possibility of noise-enhancement of the quantum transport.Comment: 10 pages, single column, 6 figures. Accepted for publication in Plos On

Psychiatric disorders in Iranian children and adolescents

Objective: The aim of the present study was to investigate the epidemiology of psychiatric disorders in children and adolescents in five provinces of Iran: Tehran, Shiraz, Isfahan, Tabriz and Mashhad. Method: In the present study, we selected 9,636 children and adolescents aged 6-18 years through multistage cluster random sampling method from Tehran, Shiraz, Isfahan, Tabriz and Mashhad. We instructed the clinical psychologists to complete the Strengths and Difficulties Questionnaire (SDQ) for the participants, and those who received a high score on SDQ, completed the Persian version of Kiddie-SADS-Present and Lifetime Version (K-SADS-PL). We used descriptive analysis and 95 confidence interval to investigate the relationship between scores of the K- SADS questionnaire and demographic factors . We used one-way ANOVA to test the significant differences among the disorders according to sex, age and province of residence. Results: Based on the results, oppositional defiant disorder (ODD) (4.45) had the highest prevalence of psychiatric disorders in the five provinces and substance abuse and alcohol abuse (0) had the lowest prevalence. In addition, attention deficit hyperactivity disorder (ADHD) had the most prevalence in boys (5.03) and ODD had the most prevalence in girls (4.05). Among the three age groups, 6 to 9 year olds had the highest rates of ADHD (5.69); 10 to 14 and 15 to 18 year olds had the highest rates of ODD (4.32 and 4.37 respectively). Among the five provinces, Tehran and Mashhad allocated the highest rates of ODD; Isfahan and Shiraz had the highest rates of ADHD; and Tabriz had the highest rates of social phobia. Conclusion: The current study revealed that the overall frequency of psychiatric disorders based on Kiddie- SADS-Present and Lifetime Version (K-SADS-PL) was higher than a similar study. Moreover, in this study, among the five provinces, Tehran and Mashhad allocated the highest rates of ODD; Isfahan and Shiraz had the highest rates of ADHD; and Tabriz had the highest rates of social phobia. Therefore, these percentage of psychiatric disorders in Iran lead us toward a greater use of consultation and mental health services

Motional effects on the efficiency of excitation transfer

Energy transfer plays a vital role in many natural and technological processes. In this work, we study the effects of mechanical motion on the excitation transfer through a chain of interacting molecules with application to biological scenarios of transfer processes. Our investigation demonstrates that, for various types of mechanical oscillations, the transfer efficiency is significantly enhanced over that of comparable static configurations. This enhancement is a genuine quantum signature, and requires the collaborative interplay between the quantum-coherent evolution of the excitation and the mechanical motion of the molecules; it has no analogue in the classical incoherent energy transfer. This effect may not only occur naturally, but it could be exploited in artificially designed systems to optimize transport processes. As an application, we discuss a simple and hence robust control technique.Comment: 25 pages, 11 figures; completely revised; version accepted for publicatio

Psychiatric disorders in Iranian children and adolescents

Objective: The aim of the present study was to investigate the epidemiology of psychiatric disorders in children and adolescents in five provinces of Iran: Tehran, Shiraz, Isfahan, Tabriz and Mashhad. Method: In the present study, we selected 9,636 children and adolescents aged 6-18 years through multistage cluster random sampling method from Tehran, Shiraz, Isfahan, Tabriz and Mashhad. We instructed the clinical psychologists to complete the Strengths and Difficulties Questionnaire (SDQ) for the participants, and those who received a high score on SDQ, completed the Persian version of Kiddie-SADS-Present and Lifetime Version (K-SADS-PL). We used descriptive analysis and 95 confidence interval to investigate the relationship between scores of the K- SADS questionnaire and demographic factors . We used one-way ANOVA to test the significant differences among the disorders according to sex, age and province of residence. Results: Based on the results, oppositional defiant disorder (ODD) (4.45) had the highest prevalence of psychiatric disorders in the five provinces and substance abuse and alcohol abuse (0) had the lowest prevalence. In addition, attention deficit hyperactivity disorder (ADHD) had the most prevalence in boys (5.03) and ODD had the most prevalence in girls (4.05). Among the three age groups, 6 to 9 year olds had the highest rates of ADHD (5.69); 10 to 14 and 15 to 18 year olds had the highest rates of ODD (4.32 and 4.37 respectively). Among the five provinces, Tehran and Mashhad allocated the highest rates of ODD; Isfahan and Shiraz had the highest rates of ADHD; and Tabriz had the highest rates of social phobia. Conclusion: The current study revealed that the overall frequency of psychiatric disorders based on Kiddie- SADS-Present and Lifetime Version (K-SADS-PL) was higher than a similar study. Moreover, in this study, among the five provinces, Tehran and Mashhad allocated the highest rates of ODD; Isfahan and Shiraz had the highest rates of ADHD; and Tabriz had the highest rates of social phobia. Therefore, these percentage of psychiatric disorders in Iran lead us toward a greater use of consultation and mental health services

Evaluation of right ventricular function and various models of delayed enhancement with cardiac magnetic resonance imaging in patients with repaired tetralogy of fallot

Background: Tetralogy of Fallot (TOF) is considered as the most frequent cyanotic congenital heart disorder. Right ventricular (RV) dysfunction is possible to be observed in patients with repaired TOF. Delayed enhancement (DE) is one of the recommended findings for RV dysfunction. Objectives: This study aimed at investigating the DE and its probable relationship with RV function through cardiac magnetic resonance (CMR). Patients and Methods: In this cross-sectional study, the values of cardiovascular magnetic resonance of 110 symptomatic patients, who had repaired TOF for 35 years, were gathered. We compared cardiac function indices (CFI) in patients with and without DE. Results: The patients had an average age of 21.93 ± 6.94 years (59.12 were male and 40.94 were female). 93.66 of the subjects showed DE and 6.44 of them did not have DE. 78.61 of the samples had DE of the right ventricular outflow tract (RVOT); whereas, 21.39 showed DE of the other sites. The differences between mean regurgitation fraction, average RV end-diastolic volume (RVEDV), average RV end systolic volume (ESV), and average RV ejection fraction in DE positive and negative patients were statistically significant (P values = 0.01, 0.04, 0.04, and 0.01, respectively.) Conclusion: DE commonly occurs as a complication of surgery to repair TOF and could be used as a factor for impaired RV function and other complications. Using CMR imaging for follow up of these patients could lead to diagnosis of these complications. © 2020, Iranian Journal of Radiology. T

An investigation on the relationship between oral candidal colony count and the duration of hemodialysis

Statement of Problem: Candidal colonies make up a part of natural oral flora and are considered as"npredisposing factors for opportunistic infections. Since hemodialysis leads to body Immune suppression and"nmake patients susceptible to opportunistic infections, it is useful to investigate the relationship between"nhemodialysis and such infections."nPurpose: The aim of the present research was to study the relationship between oral candidal colony count"nand duration of hemodialysis and also to investigate the probable necessity for prophylaxis against oral"ncandidiasis. Factors such as oral temperature, age, sex, denture, smoking, drugs, candidal microscopic view"nand clinical signs of oral infections, were also studied in relation to candidal colonies."nMaterial and Methods: The smear of posterior part of tongue and oral fluids from 114 hemodialysis patients"nin Khorshid hospital, Isfahan University of medical Sciences were cultured. The number of oral candidal"ncolonies and their microscopic view were studied in relation to the duration of hemodialysis and other factors."nTo analyze the data, Pearson and Spearman statistical tests were used."nResults: No statistical significant relationship was observed between oral candidal colony count and the"nduration of hemodialysis."nConclusion: Due to the abundant predisposing factors for oral candidal infection, the probability of oral"ncandidiasis cannot be predicted based on a single factor, namely duration of hemodialysis. As a result,"naccording to this study, the prophylactic prescription of antifungal drugs are not suggested in hemodialysis"npatients. However, the results of the present study should not be over generalized and more studies are"nrequired

Comparison of Micro-Shear Bond Strength of Resin Cements to Root Dentin of Bovine Teeth

Introduction: Nowadays resin cements are commonly used in operative dentistry but the strength of micro- shear bonds of these cements was different in various studies. The aim of this study was to compare the micro-shear bond strength of three resin cements with different mechanisms consisting of maxcem, variolink II and panavia F2.0 to bovine tooth dentin. Methods: Thirty nine longitudinal slices of bovine root dentin were prepared. Specimens were randomly divided into three equal groups. In each group one resin cement was used in cylinders with 1×2mm diameters on each slice. After setting of the cement, micro-shear bond strength was evaluated by a micro-tester device with 0.5mm/min cross head speed. Data were analyzed by ANOVA, Tukey and Bonferroni tests. Results: Micro-shear bond strength of Panavia F2.0, Maxcem and Variolink II was 15.07, 7.33 and 4.97Mpa, respectively. There were significant differences between groups. Conclusion: Micro-shear bond strength of total-Etch resin cements was lower than self-Etch ones

Effect of multiple adhesive coating on the microshear bond strength and surface microhardness of bonded dentin after using four adhesives

"nBackground and Aims: In this in-vitro study, the effect of multiple adhesive coating on the microshear bond strength of composite to dentin and surface microhardness of dentin after treatment with four adhesives (One Step Plus, One Step, Single Bond, Single Bond 2) were evaluated. "nMaterials and Methods: One hundred intact human molars were cut to obtain disks of dentin having 2 mm thickness. For the microshear bond test, sixty disks were randomly divided into four groups. In each group one type of adhesive was used. In one half of a disk two layers and in another half six layers of adhesive were applied. Cylinders with 1mm height was filled with a composite and light cured. The cross-head speed was 0.5 mm/min. Vickers microhardness was tested on forty dentin disks which divided into four groups and prepared in the same manner used for microshear bond test. Data were analyzed by Two-way ANOVA and Tukey tests. "nResults: The highest and lowest bond strength were recorded as 29.49 ± 5.74 MPa (One Step Plus; 6 layers), and 21.23 ± 4.83 MPa (One Step Plus; 2 layers), respectively. The results indicated that One Step Plus bond strength in 6 Layers was significantly higher than 2 layers. The highest and lowest dentin hardness values were"n39.08 ± 8.34VHN (Single Bond; 2 layers) and 28.53 ± 5.98 VHN (One Step Plus; 6 layers). None of the adhesives exhibited significant difference in hardness with regards to the layers applied (P>0.05). Presence of filler in adhesives had no significant effect on bond strength (P=0.05) whereas caused significant decrease in the dentin microhardness (P<0.05). In addition, type of solvent had significant effect on the bond strength and bond strength was significantly higher in acetone-base adhesives (P<0.05). However, dentin microhardness was significantly higher in the ethanol-base adhesives (P<0.05). "nConclusion: Multiple adhesive coating had no influence on the microshear bond strength of composite to dentin and dentin surface microhardness. It was dependent on the type of adhesive used

Investigation of Antimony contamination in groundwater resources: a case study

Background: Many trace elements are essential to plant, animal, and human health in small doses but they will be toxic in higher doses. Two natural processes and anthropogenic activities can be responsible for importing elements to environment (soil, water and air) which enter the human body by eating, drinking and inhalation. Antimony is a trace element that can contaminate environment in both natural and anthropogenic activities. There is no biologic role in human body for Antimony, but its low concentrations can stimulate metabolism. On the other hand, it is very toxic and can cause degradation in liver, high blood cholesterol and low blood sugar. The WHO guideline value for Antimony in surface and groundwater is 0.02 mg/l. Materials and Methods: In this study, 30 groundwater samples were collected through Kark Island. Samples were collected in polyethylene bottles (250cc) and transported to the ACME laboratory for analysis, filtered through 0.45 µm filters and acidified to pH=2 with HNO3. Results: The results of the study indicated that Antimony concentration in 82.76 of the groundwater samples with 71.34 mg/l mean value was higher than the WHO standard limit. Conclusion: Lack of outcrop geological potential of antimony, lead mines and industries confirm that oil and petrochemical industries can be responsible for contamination. It means atmospheric precipitation resulting from fossil fuel is the only reason for high Antimony concentration in Kark island