Counting Homomorphisms Modulo a Prime Number

Counting problems in general and counting graph homomorphisms in particular have numerous applications in combinatorics, computer science, statistical physics, and elsewhere. One of the most well studied problems in this area is #GraphHom(H) --- the problem of finding the number of homomorphisms from a given graph G to the graph H. Not only the complexity of this basic problem is known, but also of its many variants for digraphs, more general relational structures, graphs with weights, and others. In this paper we consider a modification of #GraphHom(H), the #_p GraphHom(H) problem, p a prime number: Given a graph G, find the number of homomorphisms from G to H modulo p. In a series of papers Faben and Jerrum, and Goebel et al. determined the complexity of #_2 GraphHom(H) in the case H (or, in fact, a certain graph derived from H) is square-free, that is, does not contain a 4-cycle. Also, Goebel et al. found the complexity of #_p GraphHom(H) for an arbitrary prime p when H is a tree. Here we extend the above result to show that the #_p GraphHom(H) problem is #_p P-hard whenever the derived graph associated with H is square-free and is not a star, which completely classifies the complexity of #_p GraphHom(H) for square-free graphs H

Knowledge, attitude, and practice of interns and practitioners graduated from the Medical Universities of Shahid Beheshti, Tehran, and Iran about colorectal cancer screening between 2014-2015

Background: Cancer is the third most common cause of death in Iran. Colorectal cancer is an ideal tumor for screening. Therefore, early diagnosis through screening can reduce its prevalence and mortality. On the other hand, knowledge of practitioners about screening programs has a direct relationship with their performance.Methods: In the present cross-sectional-educational study, knowledge, attitude, and practice of medical interns and practitioners about colorectal cancer screening were evaluated in 2014-2015 and were reviewed using Chi2 and ANOVA statistical tests. Results: From among 300 physicians surveyed, 17.3% knew the age of the screening for colorectal cancer, 73% knew the average-risk, and 68% knew the high-risk criteria correctly. About 48% of the respondents recommended Fecal Occult Blood Test (FOBT) method for population at medium risk and 75% of recommended colonoscopy as a screening method in highrisk populations. Also, 90% of physicians knew the signs and symptoms of colorectal cancer. About half of the practitioners asked their patients about risk factors and advised them to undergo screening. About 55% of the participants who had family members needing screening decided to undergo screening and 6.3% of them who needed screening, decided to undergo screening.Conclusion: Colorectal cancer is growing in the country; a fact that can be prevented. The results of the present study showed that practitioners have little knowledge of appropriate age of screening and screening methods and insufficient attitudes and actions about this issue. It is recommended that general practitioners and family physicians, who are the first lines of encounter with the patients, be properly trained.Keywords: Knowledge; Attitude; Performance; Colorectal cancer; Medical student

Firm Sustained Growth

Aquesta tesi respon a la pregunta de “Com les empreses creixen de forma sostenible en contexts dinàmics”, una de les qüestions fonamentals de la literatura d’estratègia. La tesi està formada per tres estudis que aborden diferents aspectes del creixement d´una empresa. El primer estudi proporciona un anàlisi teòric sobre “com” es produeix el creixement utilitzant la perspectiva “open-systems” i “resource-based view”. Bàsicament descriu com els recursos de les empreses creixen, i clarifica les característiques del creixement. L’estudi finalitza amb una discussió sobre la heterogeneïtat dels recursos de les empreses. El segon estudi aporta un recolzament empíric al primer estudi i descriu el creixement sostingut del consorci Airbus durant un període de 20 anys (entre 1967 i 1986). L’estudi mostra com la acumulació incremental de recursos centrada en l’estratègia de “comunalitat” ha contribuït al creixement sostenible d’Airbus. A més a més, l’estudi mostra dos períodes de creixement (1) la creació i establiment durant la primera dècada i (2) altres avanços tecnològics posteriors. Finalment, el darrer estudi aporta una teoria sobre el trencament inesperat d´una aliança i com aquest interromp el creixement de la empresa, on el divorci dirigeix l’empresa a una crisi. L’article argumenta com l’empresa pot superar la crisi i tornar a les condicions de creixement a través de la gestió dels seus recursos. L’estudi presenta com la velocitat de canvi dels recursos pot contribuir a la gestió dels recursos en crisi.Esta tesis responde a la pregunta “¿cómo pueden crecer de forme sostenible las empresas en contextos dinámicos?”, que es una de las cuestiones fundamentales en la literatura de estrategia. La tesis está formada por tres estudios sobre varios aspectos del crecimiento de las empresas. El primer estudio presenta un estudio teórico sobre “cómo” se produce el crecimiento de empresa utilizando la perspectiva de “open-systems” y “resource-based view”. Básicamente describe cómo los recursos crecen y clarifica las características de ese crecimiento. El estudio finaliza con una discusión sobre la heterogeneidad de los recursos de las empresas. El segundo estudio aporta un estudio empírico sobre el tema tratado en el primer artículo y describe el crecimiento sostenible del consorcio Airbus a lo largo de 20 años (entre 1967 y 1986). El estudio muestra cómo la acumulación incremental de recursos centrada en la estrategia de “comunalidad” ha contribuido al crecimiento sostenido de Airbus. Además, el estudio presenta dos períodos de crecimiento: (1) la creación y establecimiento durante la primera década, y (2) otros avances tecnológicos posteriores. Finalmente, el último estudio ofrece una teoría sobre la terminación inesperada de una alianza y cómo ésta interrumpe el crecimiento de la empresa, donde el divorcio lleva la empresa a la crisis. El artículo argumenta cómo la empresa puede superar la crisis y volver a las condiciones de crecimiento a través de la gestión de sus recursos. El estudio presenta cómo la velocidad de cambio de los recursos puede contribuir a la gestión de los recursos en crisis.The thesis responds to the question ´how do firms grow sustainably in dynamic environments´ as one of the fundamental questions in strategy literature. It provides three concrete studies in addressing various aspects of firm´s growth: the first study provides a theoretical study on the how of firm growth drawing on open-system perspective and resource-based view. It basically describes how firm´s resources grow and clarifies the characteristics that resources show over time. The study is finalized by discussions on the heterogeneity of firms´ resources. The second study provides an empirical support for the first study and provides an empirical case on the successful and sustained growth of Airbus consortium over 20 years from 1967 to 1986. The study shows how the incremental accumulation of resources with a focus on commonality strategy has contributed to the sustained growth of Airbus. In addition, the study shows two periods of growth (1) sparks and establishment in the first decade of Airbus growth and (2) further technological advances afterwards. Finally, the last study provides a theory of an unexpected dissolved alliance interrupting the firm growth where the divorce directs the firm into crisis. It discusses how the firm can pass the crisis and return to its growth condition through the management of its resources. The study discusses how the change speed of resources could contribute to the management of resources in crisis

Reliability optimization of hardware components and system´s topology during early design phase

To master the complexity in modern vehicle, Original Equipment Manufactures (OEM) attempt to integrate as many functions as possible into the given Electronic Control Unit (ECU), sensors, and actuators without degrading the safety and comfort functionalities. Furthermore scalability, versatility, and performance of products are key to success of electronic development in new modern vehicles. Various functional and nonfunctional requirements obviously shall be fulfilled during development of such complex systems. Choosing of hardware design structure and determination of hardware characteristics are the initial steps during early design phase. The conventional methods for selection of hardware components and topologies are mostly functional-driven. Conventional approaches are largely lacking in versatility and scalability. Due to innovative and complex trend of mechatronic product development, new approaches for hardware decision must be available which support the designers in case of changing (growing) customer demands. One of most important customer requirement for a complex system is reliability. The need for more reliable system design drives up the cost of design and influences the other system characteristics such as weight, power consumption, size, etc. These design goals like reliability, cost potentially impose conflicting requirements on the technical and economic performance of a system design. Hence, visualization and evaluating of the conflicting design preferences and early choosing optimal design are one of the most critical issues during design stage. Many multi-objective optimization approaches have been proposed to tackle this challenge. This dissertation proposes an efficient reliability optimization framework which aids the designers to determine the optimal hardware topology with optimal set of components under known technical and financial restrictions. The proposed reliability optimization framework allows describing the hardware structure of a complex system by a System Reliability Matrix (SRM) and the failure rate vector of involving hardware components. The reliability characteristics of components and the redundancy policy can be varied automatically via the SRM and its corresponding failure rate vector in order to determine optimal solutions. The proposed methodology ultimately addresses the most efficient system architecture (topology) and ascertain the unknown reliability characteristics of hardware components under consideration of financial and technical constraints. It is to be noted that the numerical deterministic search methods and genetic algorithms are applied to optimize the defined objective function under multiple constraints (reliability, cost, weight, size, etc.) and to determine the reliability characteristics of components. A general enumerative algorithm generates all design architectures (topologies) and filters the feasible design architectures (topologies) based on given constraints like budget and etc

Chemical composition, biological activities, and nutritional application of Asteraceae family herbs: A systematic review

Medicinal herbs, including the Asteraceae family (AF), have different antimicrobial and therapeutic effects. Therefore, they can be used as health factors in the food and medicinal industries. In this systematic review, the essential information was collected from the relevant databases, e.g., PubMed, Science Direct, and Google Scholar based on medicinal herbs, AF, essential oil, antimicrobial, antioxidant, therapeutic effect, and COVID-19 keywords. AF can be used as safe preservatives and food additives with a specific amount of consumption in the food industry thanks to their good flavor, antioxidant and antimicrobial effect. Due to their therapeutic effects, they can improve the health role of food. AF herbs contain important bioactive compounds, but not all of them can be used as medicine and food supplements since yarrow, chamomile, and artichoke exhibit toxic effects in high dosage, therefore, the consumption of these herbs should be considered to not endanger the health of the consume

The effect of unilateral and bilateral laparoscopic surgery for endometriosis on Anti-Mullerian Hormone (AMH) level after 3 and 6 months: a systematic review and meta-analysis

Background Endometriosis is one of the most common causes of infertility. The causes of the disease and its definitive treatments are still unclear. Moreover, Anti-Mullerian Hormone (AMH) is a glycoprotein dimer that is a member of the transient growth factors family. This research work aimed to identify the effect of unilateral and bilateral laparoscopic surgery for endometriosis on AMH levels after 3 months, and 6 months, using meta-analysis. Methods In this study, the articles published in national and international databases of SID, MagIran, IranMedex, IranDoc, Cochrane, Embase, Science Direct, Scopus, PubMed, and Web of Science (ISI) were searched to find electronically published studies between 2010 and 2019. The heterogeneous index between studies was determined using the I2 index. Results In this meta-analysis and systematic review, 19 articles were eligible for inclusion in the study. The standardized mean difference was obtained in examining of unilateral laparoscopic surgery for endometriosis (before intervention 2.8 ± 0.11, and after 3 months 2.05 ± 0.13; and before intervention 3.1 ± 0.46 and after 6 months 2.08 ± 0.31), and in examining bilateral laparoscopic surgery for endometriosis examination (before intervention 2.0 ± 08.08, and after 3 months 1.1 ± 0.1; and before intervention 2.9 ± 0.23 and after 6 months 1.4 ± 0.19). Conclusion The results of this study demonstrate that unilateral and bilateral laparoscopic surgery for endometriosis is effective on AMH levels, and the level decreases in both comparisons