Patterning the insect eye: from stochastic to deterministic mechanisms

While most processes in biology are highly deterministic, stochastic mechanisms are sometimes used to increase cellular diversity, such as in the specification of sensory receptors. In the human and Drosophila eye, photoreceptors sensitive to various wavelengths of light are distributed randomly across the retina. Mechanisms that underlie stochastic cell fate specification have been analysed in detail in the Drosophila retina. In contrast, the retinas of another group of dipteran flies exhibit highly ordered patterns. Species in the Dolichopodidae, the "long-legged" flies, have regular alternating columns of two types of ommatidia (unit eyes), each producing corneal lenses of different colours. Individual flies sometimes exhibit perturbations of this orderly pattern, with "mistakes" producing changes in pattern that can propagate across the entire eye, suggesting that the underlying developmental mechanisms follow local, cellular-automaton-like rules. We hypothesize that the regulatory circuitry patterning the eye is largely conserved among flies such that the difference between the Drosophila and Dolichopodidae eyes should be explicable in terms of relative interaction strengths, rather than requiring a rewiring of the regulatory network. We present a simple stochastic model which, among its other predictions, is capable of explaining both the random Drosophila eye and the ordered, striped pattern of Dolichopodidae.Comment: 24 pages, 4 figure

Development and psychometric evaluation of the patient safety violation scale in medical oncology units in Iran

Background: Patient safety is one of the key components of nursing care for cancer cases. Valid and reliable context-based instruments are necessary for accurate evaluation of patient safety in oncology units. The aim of the present study was to develop and evaluate the psychometric properties of the Patient Safety Violation Scale in medical oncology units in Iran. Materials and Methods: In this methodological study, a pool of 58 items was generated through reviewing the existing literature. The validity of the 58-item scale was assessed through calculating impact score, content validity ratio, and content validity index for its items as well as conducting exploratory factor analysis. The reliability of the scale was evaluated by assessing its internal consistency and testretest stability. Study sample consisted of 300 oncology nurses who were recruited from thirteen teaching hospitals affiliated to Tehran University of Medical Sciences, Tehran, Iran. Results: Sixteen items were excluded from the scale due to having low impact scores, content validity ratios, or content validity indices. In exploratory factor analysis, the remaining 42 items were loaded on five factors including patient fall, verification of patientidentity, harm during care delivery, delay in care delivery, and medication errors. These five factors explained 62 of the total variance. The Cronbach's alpha of the scale and the test-retest interclass correlation coefficient were equal to 0.933 and 0.92, respectively. Conclusions: The 42-item Patient Safety Violation Scale is a simple and short scale which has acceptable validity and reliability. Consequently, it can be used for assessing patient safety in clinical settings such as medical oncology units and for research projects

Psychometric properties of the king spiritual intelligence questionnaire (KSIQ) in physical veterans of Iran-Iraq warfare

Aims: The study's purpose was to determine reliability and validity of the King spiritual intelligence questionnaires in veterans of Iran-Iraq Warfare. Methods: In this cross sectional study, 300 veterans of the Iran-Iraq war completed the King spiritual intelligence questionnaires. Principal components analysis (PCA) with varimax rotation was used to assess domain structure of the King spiritual intelligence questionnaires. Internal and external consistency reliability was assessed with Cronbach's alpha and intra-class correlation coefficient (ICC). Results: Internal consistency of King spiritual intelligence questions estimated with Cronbach's alpha, 0.872 and intra-class correlation coefficient (ICC).872 (CI 95%: 0.84 -0.89). The construct validity of the questionnaire was calculated using exploratory factor analysis that showed 3 factors with Eigen values of greater than one, which explained in total 44.7% of the variance. (1, 8 items, α= 0.87; 2, 5. items; α = 0.89; 3, 2 items, α= 0.51). Conclusion: The Persian version of King spiritual intelligence questionnaire demonstrated suitable validity and reliability among the Veterans of Iran-Iraq Warfare. With the consideration of the proper psychometric characteristics, this questionnaire can be used to further research spiritual intelligence in this population

Solving an Optimal Control Problem of Cancer Treatment by Artificial Neural Networks

Cancer is an uncontrollable growth of abnormal cells in any tissue of the body. Many researchers have focused on machine learning and artificial intelligence (AI) based on approaches for cancer treatment. Dissimilar to traditional methods, these approaches are efficient and are able to find the optimal solutions of cancer chemotherapy problems. In this paper, a system of ordinary differential equations (ODEs) with the state variables of immune cells, tumor cells, healthy cells and drug concentration is proposed to anticipate the tumor growth and to show their interactions in the body. Then, an artificial neural network (ANN) is applied to solve the ODEs system through minimizing the error function and modifying the parameters consisting of weights and biases. The mean square errors (MSEs) between the analytical and ANN results corresponding to four state variables are 1.54e-06, 6.43e-07, 6.61e-06, and 3.99e-07, respectively. These results show the good performance and efficiency of the proposed method. Moreover, the optimal dose of chemotherapy drug and the amount of drug needed to continue the treatment process are achieved

The productivity and its barriers in public hospitals: Case study of Iran

Background: Due to the increasing health care costs, the issue of productivity in hospitals must be taken into great consideration in order to provide, preserve and promote public health services. Thus, increasing the level of productivity must become the main aim of any hospital. Objective of this study is to determine the total factor productivity and its components over the period under the study. Methods: In this cross sectional study, total factor productivity changes of hospitals affiliated to Tehran University of Medical Sciences were measured according to Malmquist index over the period 2009-2014. To estimate total productivity changes using Data Envelopment Analysis method, inputoriented and variable return to scale assumptions were applied and Deap2.1 software was used. Results: The mean value of total productivity changes was 1.013. It means that during the study period the productivity experienced a 1.3 decrease. Technological efficiency changes have the greatest influence on productivity decrease than the other factors. Scale efficiency, managerial efficiency and technical efficiency changes were ranked. Conclusion: Lack of knowledge of hospital personnel on proper application of technology in patient treatment is the main factor leading to productivity decrease resulting from technological changes in the studied hospitals. Therefore, holding courses for personnel in order to teach them the proper use of technology in diagnosis and patient care can be helpful

The effect of adipose-derived stem cells on the increased survival of crushed cartilage graft in rabbits

Background: In recent years the use of diced cartilage grafts in reconstructive surgery particulary rhinoplasty have been considered by most plastic surgeons. However, longterm resorption usually occurs. Stem cells are a powerful tool for reconstructive surgery to rebuild and maintain tissue with reduced complications. Since the adipose tissuederived stem cells (ADSCs) can rebuild a wide variety of tissues such as skin, fat, bone and cartilage are used, this is a very good chance for cosmetic surgery. The aim of this study was to examine the effects of adipose-derived stem cells on the viability of diced cartilage grafts. Methods: This interventional study was performed on May 2014 in animal laboratory of Hazrat Fatima Hospital on 10 New Zealand white male rabbits, weighing 2000-2500 grams, approximately 12 to 16 weeks of age. Stem cells was harvested from inguinal adipose tissue of each rabbits. After completely removing the skin and perichondrium, cartilage became divided into two equal pieces using a scalpel. Then place the ear amputation was restored by nylon 4 zero. After weighing cartilages, on either side of the center line on the back of each rabbits, left and right, subcutaneous pocket created equal weight and each piece of cartilage was placed in an envelope. Stem cells were injected in one side and the other side was control. The cartilage weights were recorded both before implantation and after explantation. Evaluation of living chondrocytes was conducted 12 weeks after implantation. Results: The mean difference of cartilage weights was varied between two groups (intervention and control sides), So that the average was significantly higher in stem cell side than that in the control side (P= 0.021). The average number of live chondrocytes was significantly higher in the intervention side than the control side (P< 0.001). Conclusion: Despite the unclear mechanism, these results suggest that adipose-derived stem cells can maintain the viability of diced cartilage. Because adipose-derived stem cells are autologous and easy to harvest, they can be use to improve the long-term outcomes of diced cartilage grafting. © 2016, Tehran University of Medical Sciences. All rights reserved