Atrial Flutter: Diagnosis and Management strategies

Atrial flutter (AFL) is a regular, macro reentrant arrhythmia traditionally defined as a supraventricular tachycardia with an atrial rate of 240–320 beats per minute (bpm). Pathophysiology of atrial flutter and atrial fibrillation (AF) is closely related to the similar risk of stroke and they coexist clinically. Atrial flutter is classified to cavotricuspid isthmus (CTI) dependent (or typical) and non-isthmus dependent (atypical). Isthmus is a distinct structure in the right atrium (RA) through which atrial flutter passes and makes a good target for ablation therapy. Ablation is the primary therapy in atrial flutter, particularly in CTI dependent group, with regard to its safety profile and high success rate of approximately 90%. Three-dimensional electroanatomic mapping is progressively being used to ablate atypical forms of atrial flutter

Effect of Nanoscale Fillers on the Viscoelasticity of Polymer Nanocomposites

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97070/1/AIAA2012-1825.pd

Advances on Sensitive Electron-Injection Based Cameras for Low-Flux, Short-Wave Infrared Applications

Short-wave infrared (SWIR) photon detection has become an essential technology in the modern world. Sensitive SWIR detector arrays with high pixel density, low noise levels and high signal-to-noise-ratios are highly desirable for a variety of applications including biophotonics, light detection and ranging, optical tomography, and astronomical imaging. As such many efforts in infrared detector research are directed towards improving the performance of the photon detectors operating in this wavelength range.We review the history, principle of operation, present status and possible future developments of a sensitive SWIR detector technology, which has demonstrated to be one of the most promising paths to high pixel density focal plane arrays for low flux applications. The so-called electron-injection (EI) detector was demonstrated for the first time (in 2007). It offers an overall system-level sensitivity enhancement compared to the p-i-n diode due to a stable internal avalanche-free gain. The amplification method is inherently low noise, and devices exhibit an excess noise of unity. The detector operates in linear-mode and requires only bias voltage of a few volts. The stable detector characteristics, makes formation of high yield large-format, and high pixel density focal plane arrays less challenging compared to other detector technologies such as avalanche photodetectors. Detector is based on the mature InP material system (InP/InAlAs/GaAsSb/InGaAs), and has a cutoff wavelength of 1700 nm. It takes advantage of a unique three-dimensional geometry and combines the efficiency of a large absorbing volume with the sensitivity of a low-dimensional switch (injector) to sense and amplify signals. Current devices provide high-speed response ~ 5 ns rise time, and low jitter ~ 12 ps at room temperature. The internal dark current density is ~ 1 μA/cm2 at room temperature decreasing to 0.1 nA/cm2 at 160 K.EI detectors have been designed, fabricated, and tested during two generations of development and optimization cycles. We review our imager results using the first-generation detectors. In the second-generation devices, the dark current is reduced by two orders of magnitude, and bandwidth is improved by 4 orders of magnitude. The dark current density of the EI detector is shown to outperform the state-of-the-art technology, th

Cell Mechanics in Response to Large Forces and Deformations

The topic of this thesis are cell mechanical responses to large forces. This topic is relevant because many cell types in the human body are permanently subjected to large deformations or mechanical forces. However, current methods to investigate mechanical properties at the cellular level are mostly limited to small forces and deformations, and to cell behavior in the linear regime. This thesis explores the magnetic tweezer microrheometer as a method to extend measurements to the non-linear regime of cell mechanical behavior up to the level of cell or adhesion bond breakage. In the course of experiments with an improved high-force magnetic tweezer device on living cells, several discoveries were made, including the discovery that the structural plasticity of cells is coupled to the elastic and dissipative cell properties measured in the linear regime, and that the adhesion complex of living cells shows catch bond behavior. To understand the molecular and structural origin of those behaviors, the magnetic tweezer method was combined with other state-of-the-art methods for measuring cell forces and deformations. This dissertation is divided into two main parts. In the first part, the magnetic tweezer, the cell stretcher, and the 2D traction force cytometry method are introduced. Moreover, method improvements and the implementation of device extensions are described. This includes the expansion of the force range and the application of multi-directional forces with the magnetic tweezer, a new protocol for 2D traction force microscopy measurements in order to achieve better reproducibility and higher throughput, as well as an essential improvement of cell stretcher experiments to analyze the fraction of cells that lost adhesion with the substrate, as opposed to cells that have undergone cell death. The second part describes the application of these methods and presents results of cell experimental studies on cell plasticity and cell adhesion dynamics. A central result is the discovery of a constitutive equation of cell mechanical behavior in the high-force regime that accurately predicts the mechanical response of cells to large, multiple and long-lasting forces, including the response after the forces have been removed. Moreover, a novel force spectroscopy method was implemented with the high-force magnetic tweezer: when forces acting on magnetic beads that are coupled to cell adhesion complexes are large, the adhesion bond can break. In the course of the experiments it became evident that the dynamics of bond breakage did not follow the classical Bell-type bond dynamics but instead it followed a catch bond behavior. Such catch bond behavior has been previously shown for single protein-protein adhesion bonds but not for the adhesion complex of living cells. To exclude that the observed bond-breakage dynamics was caused by a complex bond energy landscape, a novel staircase-like force protocol was introduced that confirmed catch bond behavior as the dominant source of adhesion bond breakage dynamics. In addition, the data were compared with Monte-Carlo simulations that supported the finding of a catch bond behavior. To investigate the molecular basis of cell plasticity and catch bond-type focal adhesions, experiments with cell stretcher, 2D traction force microscopy as well as a high-force magnetic tweezer were carried out in cells carrying mutations of proteins of the cytoskeleton and the focal adhesion complex, including NEDD9, filamin A, desmin, and plectin. Results show that these proteins caused pronounced mechanical alterations in cells, but none were solely responsible for the plastic cell responses or the catch bond behavior of cell adhesions, in line with the interpretation that both properties are robust, highly redundant and fundamental features of living cell.Das Thema dieser Arbeit ist die mechanische Reaktion von Zellen auf große Kräfte. Dieses Thema ist von Bedeutung, da viele Zelltypen im menschlichen Körper permanent großen Verformungen oder mechanischen Kräften ausgesetzt werden. Bisherige Verfahren, welche die mechanische Eigenschaften auf zellulärer Ebene untersuchen, sind jedoch meist auf zu kleine Kräfte und Verformungen begrenzt und behandeln daher nur das Verhalten der Zelle im linearen Bereich. Diese Arbeit untersucht den Magnetic Tweezer Mikrorheometer als eine Methode, mit Hilfe dessen Messungen des zellmechanischen Verhaltens auf den nicht-linearen Bereich bis hin zur Ebene des vollständigen Abrisses der Zelle oder der Adhäsionsbindung erweitert werden. Im Zuge der Experimente, welche mit einem verbesserten High Force Magnetic Tweezer Aufbau an lebenden Zellen durchgeführt wurden, konnten mehrere Entdeckungen gemacht werden, einschließlich der Entdeckung, dass im linearen Bereich die strukturelle Plastizität der Zellen an die elastischen sowie die dissipativen Eigenschaften gekoppelt ist, und dass der Adhäsionskomplex lebender Zellen Catch-bond-Verhalten zeigt. Um den molekularen und strukturellen Ursprung dieses Verhaltens zu verstehen, wurde der Magnetic Tweezer mit anderen mordernsten Methoden zur Messung der Kräfte und Verformungen von Zellen kombiniert. Die Dissertation ist in zwei Hauptteile gegliedert. Im ersten Teil werden der Magnetic Tweezer, der Zell-Stretcher, sowie das 2D Traction Force Zytometrie Verfahren vorgestellt. Darüber hinaus werden Verbesserungen der Methoden sowie die Implementierung von Erweiterungen der Aufbauten beschrieben. Dazu gehört der Ausbau des Kraftbereichs und die Anwendung multi-direktionaler Kräfte mit dem Magnetic Tweezer, einem neuen Protokoll für 2D Traction Force Mikroskopie-Messungen, mit welchem eine bessere Reproduzierbarkeit sowie ein höherer Durchsatz erreicht werden, als auch einer wesentlichen Verbesserung der Zell-Stretcher-Experimente zur Bestimmung des Anteils von Zellen, welche ihre Bindung mit dem Substrat verloren haben im Gegensatz zu Zellen, bei denen der Zelltot eingetreten ist. Der zweite Teil beschreibt die Anwendung dieser Methoden und präsentiert die Ergebnisse der experimentellen Untersuchungen an Zellen bezogen auf deren Plastizität sowie der Dynamik deren Zelladhäsion. Ein zentrales Ergebnis ist die Entdeckung einer konstitutiven Gleichung des zellmechanischen Verhaltens im hohen Kraftbereich, welches die mechanische Reaktion von Zellen auf große, mehrfach applizierte sowie andauernde Kräfte bis einschließlich dem Verhalten, nachdem die Kräfte entfernt wurden, genau vorhersagt. Darüber hinaus wurde eine neue Methode der Kraftspektroskopie mit dem High Force Magnetic Tweezer umgesetzt: wenn Kräfte auf magnetische Beads, welche an die Zell-Adhäsionskomplexe gebunden sind, groß sind, können deren Bindungen brechen. Im Laufe der Versuche zeigte sich, dass die Dynamik der Bindungsdissoziation nicht der klassischen Bell-Dynamik folgt, sondern Catch-bond-Verhalten zeigt. Ein solches Catch-bond-Verhalten wurde zuvor bei einzelnen Protein-Protein-Bindungen gezeigt, nicht aber beim Adhäsionskomplex von lebenden Zellen. Um auszuschließen, dass die beobachtete Dynamik dieser Bindungsdissoziation durch eine komplexe Bindungsenergielandschaft verursacht wird, wurde ein neues Treppen-Kraft-Protokoll eingeführt, welches, dass Catch-bond-Verhalten als den dominierenden Ursprung der Adhäsions-Bindungsdissoziationsdynamik bestätigt. Zudem wurden die Daten mit Monte-Carlo-Simulationen verglichen, welche den Befund eines Catch-bond-Verhaltens bekräftigen. Um die molekularen Grundlagen der Zell-Plastizität sowie der Catch-bond-artigen fokalen Adhäsioskomplexe zu untersuchen, wurden Experimente mit dem Zell-Stretcher, der 2D Traction Force Mikroskopie sowie dem High Force Magnetic Tweezer an Zellen durchgeführt, welche Mutationen von Proteinen des Zytoskeletts sowie des fokalen Adhäsionskomplexes in sich tragen, einschließlich NEDD9, Filamin A, Desmin und Plectin. Die Ergebnisse zeigen, dass diese Proteine zwar ausgeprägte mechanische Veränderungen in Zellen verursachen, aber keines davon exklusiv für die plastische Zell-Antwort oder dem Catch-bond-Verhalten der Zelladhäsionen verantwortlich ist, konform mit der Interpretation, dass beide Eigenschaften robust, hoch redundant und grundlegende Merkmale von lebenden Zellen sind

Comparison of periodic face-to-face visits and use of smartphone application during COVID-19 pandemic in clinical follow-up of range of motion in patients with distal humeral fracture

Objective: As the prevalence of the coronavirus increases, there is now more emphasis on reducing "face-to-face" patient visits. Therefore, the use of smartphones and their special medical applications can play an important role in following up patients. The aim of this study was to evaluate the use of smartphone in evaluating clinical outcomes and range of motion of patients after elbow operation. Materials and Methods: Forty patients were randomly selected from patients undergoing elbow operation. Patients were divided into two groups, so that in the first group, the patients were visited and then were followed-up for 2,6, and 12 weeks as well as 6 months after first visit by smartphone connection and delivering the pictures and videos of involved organ to the physician as well as having the physical examination him. In the second group, all assessments were performed by clinical visiting at the same time points. Results: The two groups were similar in baseline characteristics including demographics; the side of involved elbow, type of fracture, surgical approach, operation time, and mean Mepi score. Assessing the postoperative complications and also patients' satisfaction was also similar in both groups. There was no difference in different range of elbow motion degrees between the case and control groups at different times of following-up as well as the progress in motion of elbow after surgery in two groups. Moreover, there was no significant difference between the range of motion evaluated by smartphone and physical examination. Conclusion: The use of the smartphone has a high degree of accuracy and sensitivity in assessing the status of elbow range of motion after surgical treatment, both in the short and long term after surgery

A Hybrid 2D-3D CFD Model System for Offshore Pile Groups Subject to Wave Loading

Experimental and Computational Hydraulic

Misdiagnosis in Patients with Cervicogenic Headache: The Case Reports of Three Adults

Introduction: Cervicogenic headache is known to be the most controversial type of headache, because its diagnosis is difficult and usually associated with errors. The signs and symptoms of this headache confuse therapists and cause misdiagnosis; definitive diagnostic criteria and physical tests should be used to accurately diagnose cervicogenic headaches. The current study investigated patients suffering from headaches, then reassessed them using a new diagnosis protocol, and finally provided them with physiotherapy using clinical reasoning strategies. Materials and Methods: In this study, three patients who had suffered headaches and tolerated inappropriate treatment due to misdiagnosis were evaluated using diagnostic criteria and physical examination based on the International Headache Society (IHS) criteria. Cervicogenic headache was diagnosed, and accordingly, physiotherapy with a multi-modal intervention approach based on clinical reasoning was administered. The outcome of treatment was assessed using the headache index questionnaire. Conclusion: Subjects who had suffered, on average, 15 years of chronic, medicine resistance headaches were evaluated. Cervicogenic headache was diagnosed in each of them and physiotherapy was begun. An average improvement rate of 74% was achieved based on the headache index formula. It can be concluded that the use of physical tests in addition to diagnostic criteria will decrease the rate of misdiagnosed cervicogenic headache, and physiotherapy can be the appropriate treatment.Keywords: Cervicogenic headache, Physiotherapy, Misdiagnosis, Multimodal intervention