Feedback Control as a Framework for Understanding Tradeoffs in Biology

Control theory arose from a need to control synthetic systems. From regulating steam engines to tuning radios to devices capable of autonomous movement, it provided a formal mathematical basis for understanding the role of feedback in the stability (or change) of dynamical systems. It provides a framework for understanding any system with feedback regulation, including biological ones such as regulatory gene networks, cellular metabolic systems, sensorimotor dynamics of moving animals, and even ecological or evolutionary dynamics of organisms and populations. Here we focus on four case studies of the sensorimotor dynamics of animals, each of which involves the application of principles from control theory to probe stability and feedback in an organism's response to perturbations. We use examples from aquatic (electric fish station keeping and jamming avoidance), terrestrial (cockroach wall following) and aerial environments (flight control in moths) to highlight how one can use control theory to understand how feedback mechanisms interact with the physical dynamics of animals to determine their stability and response to sensory inputs and perturbations. Each case study is cast as a control problem with sensory input, neural processing, and motor dynamics, the output of which feeds back to the sensory inputs. Collectively, the interaction of these systems in a closed loop determines the behavior of the entire system.Comment: Submitted to Integr Comp Bio

Evaluation of apertura piriformis and related cranial anatomical structures through computed tomography: golden ratio

Background: The purpose of study was to evaluate normal morphometric measurements of piriform aperture (PA) by limiting the age range in genders to show the morphometry of the relevant and close proximal cranial structures; and also to investigate whether these are in compliance with the golden ratio. Materials and methods: Our study was performed on 83 (42 female, 41 male) multidetector computed tomography images obtained from patients. A total of 14 morphological measurements were performed including the height of PA, the width of PA and 12 cranial structures; and these measurements were evaluated for compliance with the golden ratio. The differences of 14 parameters between the genders and age groups, and also the interaction of these two factors were analysed. Results: In our morphometric study, significant difference between the genders was found in all measurements except for the distance between vertex and rhinion (V~Rh), between rhinion and right foramen supraorbitalis (Rh~FSOR), between rhinion and left FSO (Rh~FSOL), and the width of PA on the level between the right and left foramen infraorbitalis (PAW~FIO) with the difference valid for both age subgroups (p < 0.05). When the differences between the age subgroups were evaluated, there was significant difference only at the widest distance of cranium (CW; p = 0.008); and it was observed that the average has increased with age in both genders. When the golden ratio was examined, the ratio of the distance between anterior nasal spine and nasion to the height of piriform aperture (NSA~N:PAH) was found to be within the limits of the golden ratio in males (p = 0.074). No golden ratio has been found in females. Conclusions: In our study, significant differences were detected between genders in all parameters of PA and in some parameters of the close cranial structures in the age group we examined. The effect of age was detected only in the CW parameter, and the PA and close cranial structures were not affected. In our study, the averages of the morphometric measurements of 13 parameters of young adults were determined. The PA and surrounding cranial structures are important for the area and related surgical procedures; however, gender differences must be considered in this respect. In addition to this, in the PA, which is the anterior limit of the skeletal nose in males, the NSA~N:PAH ratio having the ideal golden ratio limits is valuable in aesthetical terms and due to its position of the PA in the face

Detecting imipenem resistance in Acinetobacter baumannii by automated systems (BD Phoenix, Microscan WalkAway, Vitek 2); high error rates with Microscan WalkAway

<p>Abstract</p> <p>Background</p> <p>Increasing reports of carbapenem resistant <it>Acinetobacter baumannii </it>infections are of serious concern. Reliable susceptibility testing results remains a critical issue for the clinical outcome. Automated systems are increasingly used for species identification and susceptibility testing. This study was organized to evaluate the accuracies of three widely used automated susceptibility testing methods for testing the imipenem susceptibilities of <it>A. baumannii </it>isolates, by comparing to the validated test methods.</p> <p>Methods</p> <p>Selected 112 clinical isolates of <it>A. baumanii </it>collected between January 2003 and May 2006 were tested to confirm imipenem susceptibility results. Strains were tested against imipenem by the reference broth microdilution (BMD), disk diffusion (DD), Etest, BD Phoenix, MicroScan WalkAway and Vitek 2 automated systems. Data were analysed by comparing the results from each test method to those produced by the reference BMD test.</p> <p>Results</p> <p>MicroScan performed true identification of all <it>A. baumannii </it>strains while Vitek 2 unidentified one strain, Phoenix unidentified two strains and misidentified two strains. Eighty seven of the strains (78%) were resistant to imipenem by BMD. Etest, Vitek 2 and BD Phoenix produced acceptable error rates when tested against imipenem. Etest showed the best performance with only two minor errors (1.8%). Vitek 2 produced eight minor errors(7.2%). BD Phoenix produced three major errors (2.8%). DD produced two very major errors (1.8%) (slightly higher (0.3%) than the acceptable limit) and three major errors (2.7%). MicroScan showed the worst performance in susceptibility testing with unacceptable error rates; 28 very major (25%) and 50 minor errors (44.6%).</p> <p>Conclusion</p> <p>Reporting errors for <it>A. baumannii </it>against imipenem do exist in susceptibility testing systems. We suggest clinical laboratories using MicroScan system for routine use should consider using a second, independent antimicrobial susceptibility testing method to validate imipenem susceptibility. Etest, whereever available, may be used as an easy method to confirm imipenem susceptibility.</p

Identifying risk factors for blood culture negative infective endocarditis: An international ID-IRI study

Background: Blood culture-negative endocarditis (BCNE) is a diagnostic challenge, therefore our objective was to pinpoint high-risk cohorts for BCNE. Methods: The study included adult patients with definite endocarditis. Data were collected via the Infectious Diseases International Research Initiative (ID-IRI). The study analysing one of the largest case series ever reported was conducted across 41 centers in 13 countries. We analysed the database to determine the predictors of BCNE using univariate and logistic regression analyses. Results: Blood cultures were negative in 101 (11.65 %) of 867 patients. We disclosed that as patients age, the likelihood of a negative blood culture significantly decreases (OR 0.975, 95 % CI 0.963–0.987, p &lt; 0.001). Additionally, factors such as rheumatic heart disease (OR 2.036, 95 % CI 0.970–4.276, p = 0.049), aortic stenosis (OR 3.066, 95 % CI 1.564–6.010, p = 0.001), mitral regurgitation (OR 1.693, 95 % CI 1.012–2.833, p = 0.045), and prosthetic valves (OR 2.539, 95 % CI 1.599–4.031, p &lt; 0.001) are associated with higher likelihoods of negative blood cultures. Our model can predict whether a patient falls into the culture-negative or culture-positive groups with a threshold of 0.104 (AUC±SE = 0.707 ± 0.027). The final model demonstrates a sensitivity of 70.3 % and a specificity of 57.0 %. Conclusion: Caution should be exercised when diagnosing endocarditis in patients with concurrent cardiac disorders, particularly in younger cases

Mortality Associated with Surgical Site Infections Following Cardiac Surgery: Insights from the International ID-IRI Study

Objectives: Surgical site infections (SSIs) after cardiac surgery increase morbidity and mortality rates. This multicenter study aimed to identify mortality risk factors associated with SSIs after heart surgery. Methods: Conducted from January to March 2023, this prospective study included 167 patients aged &gt;16 years with post-heart surgery SSIs. The primary focus was the 30-day mortality. Univariate analysis and multivariate logistic regression utilizing the backward elimination method were used to establish the final model. Results: Several factors significantly correlated with mortality. These included urinary catheterization (odds ratio [OR] 14.197; 90% confidence interval [CI] 12.198-91.721]), emergent surgery (OR 8.470 [90% CI 2.028-35.379]), valvular replacement (OR 4.487 [90% CI 1.001-20.627]), higher quick Sequential Organ Failure Assessment scores (OR 3.147 [90% CI 1.450-6.827]), advanced age (OR 1.075 [90% CI 1.020-1.132]), and postoperative re-interventions within 30 days after SSI (OR 14.832 [90% CI 2.684-81.972]). No pathogens were isolated from the wound cultures of 53 (31.7%) patients. A total of 43.1% of SSIs (n = 72) were due to gram-positive microorganisms, whereas 27.5% of cases (n = 46) involved gram-negatives. Among the gram-positive bacteria, Staphylococci (n = 30, 17.9%) were the predominant microorganisms, whereas Klebsiella (n = 16, 9.6%), Escherichia coli (n = 9, 5.4%), and Pseudomonas aeruginosa (n = 7, 4.2%) were the most prevalent. Conclusions: To mitigate mortality after heart surgery, stringent infection control measures and effective surgical antisepsis are crucial, particularly, in the elderly. The clinical progression of the disease is reflected by the quick Sequential Organ Failure Assessment score and patient re-intervention, and effective treatment is another essential component of SSI management

5G Mobile Communication Systems: Fundamentals, Challenges, and Key Technologies

Wireless and mobile communication technologies exhibit remarkable changes in every decade. The necessity of these changes is based on the changing user demands and innovations offered by the emerging technologies. This chapter provides information on the current situation of fifth generation (5G) mobile communication systems. Before discussing the details of the 5G networks, the evolution of mobile communication systems is considered from first generation to fourth generation systems. The advantages and weaknesses of each generation are explained comparatively. Later, technical infrastructure developments of the 5G communication systems have been evaluated in the context of system requirements and new experiences of users such as 4K video streaming, tactile Internet, and augmented reality. After the main goals and requirements of the 5G networks are described, the planned targets to be provided in real applications by this new generation systems are clarified. In addition, different usage scenarios and minimum requirements for the ITU-2020 are evaluated. On the other hand, there are several challenges to be overcome for achieving the intended purpose of 5G communication systems. These challenges and potential solutions for them are described in the proceeding subsections of the chapter. Furthermore, massive multiple-input multiple-output (MIMO), millimeter wave (mmWave), mmWave massive MIMO, and beamforming techniques are clarified in a detail which are taken into account as promising key technologies for the 5G networks. Besides, potential application areas and application examples of the 5G communication systems are covered at the end of this chapter. © Springer Nature Singapore Pte Ltd 2019.Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK, (BIDEB-2219