Surgical Therapy of Atrial Fibrillation

Atrial fibrillation (AF) can be found in an increasing number of cardiac surgical patients due to a higher patient's age and comorbidities. Atrial fibrillation is known, however, to be a risk factor for a greater mortality, and one aim of intraoperative AF treatment is to approximate early and long-term survival of AF patients to survival of patients with preoperative sinus rhythm. Today, surgeons are more and more able to perform less complex, that is, minimally invasive cardiac surgical procedures. The evolution of alternative ablation technologies using different energy sources has revolutionized the surgical therapy of atrial fibrillation and allows adding the ablation therapy without adding significant risk. Thus, the surgical treatment of atrial fibrillation in combination with the cardiac surgery procedure allows to improve the postoperative long-term survival and to reduce permanent anticoagulation in these patients. This paper focuses on the variety of incisions, lesion sets, and surgical techniques, as well as energy modalities and results of AF ablation and also summarizes future trends and current devices in use

Abandon:World Picture Conference

Keynote by Laurence Rickels Live performance by Sandra Gibson and Luis Recoder The term abandon encompasses radical renunciation and immersive indulgence in its oscillation between abandonment of and abandonment to, between restraint and luxury, mindfulness and neglect. When we speak of abandonment we indicate a situation in which we take leave of something, or disband a collective entity, or else act in a way that suggests a disaggregation of certain protocols of behaviour, or belonging (as when we &#8216;laugh with abandon&#8217;). Discourses and scenes of media and politics are generally highly invested in ideas of taking-leave, breaking apart or away, acting with abandon. In the present moment, we believe the term resonates in manifold ways. For instance: with often painful choices between theoretical and political models that have outlasted their effectiveness but to which there seem to be no alternatives; with turns to abandoned objects as new sources of ontologies in which the turn itself is a mode of abandoning an established political-theoretical project; with the obdurate &#8216;problem&#8217; of pleasure in aesthetics and aesthetic theory as either the obstacle or the medium of the aesthetic’s interface with the political; with the cathexis of the body and its phenomenology as an instrument and medium of political and aesthetic experimentation; with attempts to relinquish the human, and its attendant association with agency, as a category of experience; with contemporary experiences/fantasies of control and resistance to control; with theatricalizations of abjuration and gratification.Abandon: World Picture Conference, conference, ICI Berlin, 7–8 November 2014 <https://doi.org/10.25620/e141107

Cosmological Multi-Black Hole Solutions

We present simple, analytic solutions to the Einstein-Maxwell equation, which describe an arbitrary number of charged black holes in a spacetime with positive cosmological constant $\Lambda$. In the limit $\Lambda=0$, these solutions reduce to the well known Majumdar-Papapetrou (MP) solutions. Like the MP solutions, each black hole in a $\Lambda >0$ solution has charge $Q$ equal to its mass $M$, up to a possible overall sign. Unlike the $\Lambda = 0$ limit, however, solutions with $\Lambda >0$ are highly dynamical. The black holes move with respect to one another, following natural trajectories in the background deSitter spacetime. Black holes moving apart eventually go out of causal contact. Black holes on approaching trajectories ultimately merge. To our knowledge, these solutions give the first analytic description of coalescing black holes. Likewise, the thermodynamics of the $\Lambda >0$ solutions is quite interesting. Taken individually, a $|Q|=M$ black hole is in thermal equilibrium with the background deSitter Hawking radiation. With more than one black hole, because the solutions are not static, no global equilibrium temperature can be defined. In appropriate limits, however, when the black holes are either close together or far apart, approximate equilibrium states are established.Comment: 15 pages (phyzzx), UMHEP-380 (minor referencing error corrected

Semiclassical vs. Exact Solutions of Charged Black Hole in Four Dimensions and Exact O(d,d) Duality

We derive a charged black hole solution in four dimensions described by $SL(2,R)\times SU(2)\times U(1)/U(1)^2$ WZW coset model. Using the algebraic Hamiltonian method we calculate the corresponding solution that is exact to all orders in ${1\over k}$. It is shown that unlike the 2D black hole, the singularity remains also in the exact solution, and moreover, in some range of the gauge parameter the space-time does not fulfil the cosmic censor conjecture, $i.e.$ we find a naked singularity outside the black hole. Exact dual models are derived as well, one of them describes a 4D space-time with a naked singularity. Using the algebraic Hamiltonian approach we also find the exact to all orders $O(d,d)$ transformation of the metric and the dilaton field for general WZW coset models and show the correction with respect to the transformations in one loop order.Comment: 42 pages, (typographical errors in pages 33 and 35

Combined Coronary CT-Angiography and TAVI-Planning: A Contrast-Neutral Routine Approach for Ruling-Out Significant Coronary Artery Disease

Background: Significant coronary artery disease (CAD) is a common finding in patients undergoing transcatheter aortic valve implantation (TAVI). Assessment of CAD prior to TAVI is recommended by current guidelines and is mainly performed via invasive coronary angiography (ICA). In this study we analyzed the ability of coronary CT-angiography (cCTA) to rule out significant CAD (stenosis ≥ 50%) during routine pre-TAVI evaluation in patients with high pre-test probability for CAD. Methods: In total, 460 consecutive patients undergoing pre-TAVI CT (mean age 79.6 ± 7.4 years) were included. All patients were examined with a retrospectively ECG-gated CT-scan of the heart, followed by a high-pitch-scan of the vascular access route utilizing a single intravenous bolus of 70 mL iodinated contrast medium. Images were evaluated for image quality, calcifications, and significant CAD; CT-examinations in which CAD could not be ruled out were defined as positive (CAD+). Routinely, patients received ICA (388/460; 84.3%; Group A), which was omitted if renal function was impaired and CAD was ruled out on cCTA (Group B). Following TAVI, clinical events were documented during the hospital stay. Results: cCTA was negative for CAD in 40.2% (188/460). Sensitivity, specificity, PPV, and NPV in Group A were 97.8%, 45.2%, 49.6%, and 97.4%, respectively. Median coronary artery calcium score (CAC) was higher in CAD+-patients but did not have predictive value for correct classification of patients with cCTA. There were no significant differences in clinical events between Group A and B. Conclusion: cCTA can be incorporated into pre-TAVI CT-evaluation with no need for additional contrast medium. cCTA may exclude significant CAD in a relatively high percentage of these high-risk patients. Thereby, cCTA may have the potential to reduce the need for ICA and total amount of contrast medium applied, possibly making pre-procedural evaluation for TAVI safer and faster

Pair Creation of Dilaton Black Holes

We consider dilaton gravity theories in four spacetime dimensions parametrised by a constant $a$, which controls the dilaton coupling, and construct new exact solutions. We first generalise the C-metric of Einstein-Maxwell theory ($a=0$) to solutions corresponding to oppositely charged dilaton black holes undergoing uniform acceleration for general $a$. We next develop a solution generating technique which allows us to ``embed" the dilaton C-metrics in magnetic dilaton Melvin backgrounds, thus generalising the Ernst metric of Einstein-Maxwell theory. By adjusting the parameters appropriately, it is possible to eliminate the nodal singularities of the dilaton C-metrics. For $a<1$ (but not for $a\ge 1$), it is possible to further restrict the parameters so that the dilaton Ernst solutions have a smooth euclidean section with topology $S^2\times S^2-{\rm\{pt\}}$, corresponding to instantons describing the pair production of dilaton black holes in a magnetic field. A different restriction on the parameters leads to smooth instantons for all values of $a$ with topology $S^2\times \R^2$.Comment: 22 pages, EFI-93-51, FERMILAB-Pub-93/272-A, UMHEP-393. (Asymptotics of Ernst solutions clarified, typos repaired

Universal corrections to entanglement entropy of local quantum quenches

We study the time evolution of single interval Renyi and entanglement entropies following local quantum quenches in two dimensional conformal field theories at finite temperature for which the locally excited states have a finite temporal width, \epsilon. We show that, for local quenches produced by the action of a conformal primary field, the time dependence of Renyi and entanglement entropies at order \epsilon^2 is universal. It is determined by the expectation value of the stress tensor in the replica geometry and proportional to the conformal dimension of the primary field generating the local excitation. We also show that in CFTs with a gravity dual, the \epsilon^2 correction to the holographic entanglement entropy following a local quench precisely agrees with the CFT prediction. We then consider CFTs admitting a higher spin symmetry and turn on a higher spin chemical potential \mu. We calculate the time dependence of the order \epsilon^2 correction to the entanglement entropy for small \mu, and show that the contribution at order \mu^2 is universal. We verify our arguments against exact results for minimal models and the free fermion theory

STUDI EKSPERIMENTAL KARAKTERISTIK KUAT TEKAN DAN KARAKTERISTIK PEMBAKARAN BRIKET DAUN CENGKEH DAN JERAMI PADI

Penelitian ini mempelajari tentang karakteristik kuat tekan dan karakteristik pembakaran briket daun cengkeh dan jerami padi. Pembriketan dilakukan dengan menggunakan mesin pres hidrolik dengan tekanan pembriketan sebesar 450 kg/cm2, dengan bahan pengikat dan tanpa bahan pengikat. Bahan pengikat yang digunakan adalah lem kanji dengan kadar 5 %. Briket berbentuk silinder dengan diameter sekitar 3 cm dan tinggi 5 cm. Variasi parameter pembriketan yang digunakan adalah ukuran butir 20, 40 dan 80 mesh, kadar air 15 %, 20 % dan 25 %, serta suhu pembriketan sebesar 60 oC, 80 oC, 100 oC dan 120 oC. Uji pembakaran dilakukan dalam tungku berbentuk tabung horisontal berdiameter dalam 170 mm. Variasi perameter uji pembakaran yang digunakan adalah kecepatan aliran udara sebesar 0,6 m/s; 0,8 m/s; 1,0 m/s dan 1,2 m/s serta variasi ukuran butir sebesar 20, 40, dan 80 mesh. Suhu pembriketan berpengaruh signifikan terhadap peningkatan kuat tekan briket. Dari hasil uji pembakaran dapat ditentukan besarnya laju pembakaran, profil suhu pembakaran, nilai energi aktivasi (E ), konstanta Arrhenius (A), dan emisi CO. Dari semua percobaan, kadar emisi CO puncak lebih dari 400 ppm. Kata kunci: kuat tekan, daun cengkeh, jerami, bahan pengikat, ukuran butir, suhu pembriketan, kadar air, laju pembakaran, energi aktivasi, emisi CO.

A flexible back-contact perovskite solar micro-module

Back-contact perovskite solar cells are fabricated by depositing methylammonium lead iodide perovskite into micron-sized grooves, with opposite walls of each groove being coated with either n- or p-type selective contacts. V-Shaped grooves are created by embossing a polymeric substrate, with the different charge-selective electrodes deposited onto the walls of the groove using a directional evaporation technique. We show that individual grooves act as photovoltaic devices, having a power conversion efficiency of up to 7.3%. By series-connecting multiple grooves, we create integrated micro-modules that build open circuit voltages up to nearly 15 V and power conversion efficiencies over 4%. The devices created are fully flexible, do not include rare metals, and are processed using techniques applicable to roll-to-roll processing