Optimisation of flow resistance and turbulent mixing over bed forms

Previous work on the interplay between turbulent mixing and flow resistance for flows over periodic rib roughness elements is extended to consider the flow over idealized shapes representative of naturally occurring sedimentary bed forms. The primary motivation is to understand how bed form roughness affects the carrying capacity of sediment-bearing flows in environmental fluid dynamics applications, and in engineering applications involving the transport of particulate matter in pipelines. For all bed form shapes considered, it is found that flow resistance and turbulent mixing are strongly correlated, with maximum resistance coinciding with maximum mixing, as was previously found for the special case of rectangular roughness elements. Furthermore, it is found that the relation between flow resistance to eddy viscosity collapses to a single monotonically increasing linear function for all bed form shapes considered, indicating that the mixing characteristics of the flows are independent of the detailed morphology of individual roughness elements

Optimised mixing and flow resistance during shear flow over a rib roughened boundary

A series of numerical investigations has been performed to study the effect of lower boundary roughness on turbulent flow in a two-dimensional channel. The roughness spacing to height ratio, w/k, has been investigated over the range 0.12 to 402 by varying the horizontal rib spacing. The square roughness elements each have a cross-sectional area of (0.05 H)2, where H is the full channel height. The Reynolds number, Reτ is fixed based on the value of the imposed pressure gradient, dp/dx, and is in the range 6.3 × 103 − 4.5 × 104. A Reynolds Averaged Navier–Stokes (RANS) based turbulence modelling approach is adopted using a commercial CFD code, ANSYS-CFX 14.0. Measurements of eddy viscosity and friction factor have been made over this range to establish the optimum spacings to produce maximum turbulence enhancement, mixing and resistance to flow. These occur when w/k is approximately 7. It is found that this value is only weakly dependent on Reynolds number, and the decay rate of turbulence enhancement as a function of w/k ratio beyond this optimum spacing is slow. The implications for heat transfer design optimisation and particle transport are considered

Evaluation of the relationship between serum lactate and potassium levels with clinical signs of calf diarrhea syndrome in calves referred to the large animal clinic of Islamic Azad University of Tabriz Branch

Diarrhea in newborn calves is often accompanied by metabolic acidosis which is the main reason for the establishment of symptoms related to diarrhea syndrome such as lethargy, recumbency, decreased suckling strength and etc. In order to be informed of lactic acid levels in the blood of diarrheaic calves, samples were collected from 100 affected and 20 healthy calves as the control group referred to the large animal clinic. In this respect, 120 blood samples were collected from the jugular vein using Venoject tubes, their sera separated by centrifugation and stored at -20°C in micro tubes and lactic acid levels were determined by enzymatic method. In this study, mean lactic acid levels of 4.72±0.02 mmol/lit and 1.2±0.05 mmol/lit were recorded in diarrheaic and healthy calves. Also, mean potassium levels in healthy and diarrheaic calves were 4.20±0.03 mmol/lit and 6.70±0.01 mmol/lit respectively. The results of the present study indicated that there was a significant relationship between diarrheaic and serumic levels of lactic acid and potassium (

Adjunctive treatment with aripiprazole for risperidone-induced hyperprolactinemia

Fatemeh Ranjbar,1 Homayoun Sadeghi-Bazargani,2,3 Parisa Niari Khams,1 Asghar Arfaie,1 Azim Salari,4 Mostafa Farahbakhsh1 1Clinical Psychiatry Research Center, Tabriz University of Medical Sciences, Tabriz, East Azerbaijan, Iran; 2Road Traffic Injury Research Center, Department of Statistics & Epidemiology, Tabriz University of Medical Sciences, Tabriz, Iran; 3World Health Organization Collaborating Center on Community Safety Promotion, Karolinska Institute, Stockholm, Sweden; 4Emam Khomeini Hospital, Naghadeh, West Azerbaijan, Iran Background: Antipsychotics have been used for more than 50 years in the treatment of schizophrenia and many other psychiatric disorders. Prolactin levels usually increase in patients treated with risperidone. Aripiprazole, which has a unique effect as an antipsychotic, is a D2 receptor partial agonist. It is an atypical antipsychotic with limited extrapyramidal symptoms. Since it acts as an antagonist in hyperdopaminergic conditions and as an agonist in hypodopaminergic conditions, it does not have adverse effects on serum prolactin levels. The present study aimed to investigate the effect of aripiprazole on risperidone-induced hyperprolactinemia. Methods: This before-and-after clinical trial was performed in 30 patients. Baseline prolactin levels were measured in all patients who were candidates for treatment with risperidone. In subjects with elevated serum prolactin, aripiprazole was added to their treatment. Serum prolactin levels were measured during the first week, second week, and monthly thereafter for at least 3 months or until prolactin levels became normal. The data were analyzed using Stata version 11 software. Survival analysis and McNemar’s test were also performed. Results: The mean age of the participants was 30.8 years. Prolactin levels normalized in 23 (77%) participants during the study, and menstrual disturbances normalized in 25 (83.3%). Prolactin levels normalized in most patients between days 50 and 110. The median time to recovery based on normalization of prolactin was 84 days. Psychotic symptoms were present in 26 subjects at baseline, but in only two by the end of the study. Conclusion: The results of this study confirm the effects of aripiprazole in reducing risperidone-induced hyperprolactinemia and its sequelae. Aripiprazole also led to significant improvements in psychotic symptoms when compared with those present prior to treatment with aripiprazole. Keywords: hyperprolactinemia, aripiprazole, risperidone, psychotic disorde