In a sequence of otherwise equal sounds, listeners tend to hear a series of trochees (groups of two sounds with an initial beat) when every other sound is louder; they tend to hear a series of iambs (groups of two sounds with a final beat) when every other sound is longer. The article presents evidence that this so-called "Iambic-Trochaic Law" (ITL) is a consequence of the way listeners parse the signal along two orthogonal dimensions, grouping (Which tone is first/last?) and prominence (Which tone is prominent?). A production experiment shows that in speech, intensity and duration correlate when encoding prominence, but anticorrelate when encoding grouping. A model of the production data shows that the ITL emerges from the cue distribution based on a listener's predicted decisions about prominence and grouping respectively. This, and further predictions derived from the model, are then tested in speech and tone perception. The perception results provide evidence that intensity and duration are excellent cues for grouping and prominence, but poor cues for the distinction between iamb and trochee per se. Overall, the findings illustrate how the ITL derives from the way listeners recover two orthogonal perceptual dimensions, grouping and prominence, from a single acoustic stream. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Roundtable Discussion: How the AAMI COVID-19 Response Team Responded to Crisis.

We report on the generation of four spatially multiplexed picosecond 40 GHz pulse trains in a km long 6 LP multimode optical fiber. The principle of operation is based on the parallel nonlinear compression of initial beat signals into well separated pulse trains owing to intramodal multiple four-wave mixings. A series of four 40 GHz dual-frequency beatings at different wavelengths are simultaneously injected into the ${{\rm LP}_{01}}$LP01, ${{\rm LP}_{11}}$LP11, ${{\rm LP}_{02}}$LP02, and ${{\rm LP}_{12}}$LP12 modes of a 1.8 km long graded-index few-mode fiber. The combined effects of Kerr nonlinearity and anomalous chromatic dispersion lead to the simultaneous generation of four spatially multiplexed frequency combs, which correspond in the temporal domain to the compression of these beat signals into picosecond pulses. The temporal profiles of the output pulse trains demultiplexed from each spatial mode show that well-separated picosecond pulses with negligible pedestals are then generated.

A major challenge in cardiac tissue engineering is the host’s immune response to artificial materials. To overcome this problem, we established a scaffold-free system for assembling cell constructs using an automated Bio-3D printer. This printer has previously been used to fabricate other three-dimensional (3D) constructs, including liver, blood vessels, and cartilage. In the present study, we tested the function in vivo of scaffold-free cardiac tubular construct fabricated using this system. Cardiomyocytes derived from induced pluripotent stem cells (iCells), endothelial cells, and fibroblasts were combined to make the spheroids. Subsequently, tubular cardiac constructs were fabricated by Bio-3D printer placing the spheroids on a needle array. Notably, the spheroid fusion and beat rate in the constructs were observed while still on the needle array. After removal from the needle array, electrical stimulation was used to test responsiveness of the constructs. An increased beat rate was observed during stimulation. Importantly, the constructs returned to their initial beat rate after stimulation was stopped. In addition, histological analysis shows cellular reorganization occurring in the cardiac constructs, which may mimic that observed during organ transplantation. Taken together, our results indicate that these engineered cardiac tubular constructs, which address both the limited supply of donor tissues as well as the immune-induced transplant rejection, has potential to be used for both clinical and drug testing applications. To our knowledge, this is the first time that cardiac tubular constructs have been produced using optimized Bio-3D printing technique and subsequently tested for their use as cardiac pumps.

The Different Persons of Amiri Baraka:Collectivity, Singularity, and Becoming-Minor James Liner (bio) Now something that you formerly loved as a truth or probability strikes you as an error; you shed it and fancy that this represents a victory for your reason. But perhaps this error was as necessary for you then, when you were still a different person—you are always a different person—as are all your present “truths”.… —Nietzsche (1974, 245–46) People always say, “Well, what’s Baraka doing now? He keeps on changing.” —Baraka (1984, 334) …everyone is a little group…and must live as such…. —Deleuze and Guattari (1983, 362) In his texts as in his life, Amiri Baraka refuses closure and takes flight. His career is punctuated by sharp breaks and extreme, often dramatic transitions in form, politics, places and manners of living, even personal identity (successively LeRoy Jones, LeRoi Jones, Imamu Ameer Barakat, Imamu Amiri Baraka, Amiri Baraka). More than just an idiosyncratic predisposition, Baraka makes of this protean flux an aesthetic principle. In his 1964 essay “Hunting Is Not Those Heads on the Wall,” Baraka famously condemns the artifact worship of “academic” literary critics (read: New Critics) and advocates a process-oriented aesthetic emphasizing the active creating expressed in the gerund “art-ing” over the reification of that process in the noun art (1966, 173–78). Art and literature, he proposes, must be viewed as an active unfolding. Contrary to the belletristic desire to seal off a text from history, Baraka’s texts tap into and channel the flows of history, not merely spilling off the page but exploding: his controversial post-9/11 poem, “Somebody Blew Up America” (2002), sounds “Like an Owl / Exploding in fire…/In terrible flame like the whistle of a crazy dog” (2003, 50). Unlike one of his erstwhile [End Page 247] modernist inspirations, T. S. Eliot, Baraka will never be pinned and wriggling on a wall. This refusal to be pinned down is evident in the wide range of Baraka’s literary output: from his literary debut as a Beat latecomer with Preface to a Twenty Volume Suicide Note…(1961) to his death in 2014, Baraka moved through a series of discrete periods, distinguishable both formally and ideologically.1 After an initial Beat period spanning the years 1959 to 1962 and characterized by a free-verse poetic style and a strident antiformalism that insists on absolute aesthetic freedom (exemplified in his early essay on poetics, “How You Sound??” [1959]), Baraka underwent a transition that lasted until his adoption of Black cultural nationalism in 1965. Works of the transitional period evince a progressive “blackening” of both content and form, the emergence and development of what William J. Harris calls “the jazz aesthetic” (1985); introducing Home: Social Essays (1966), which chronicles these years from a later Black nationalist vantage, Baraka famously writes: “By the time this book appears, I will be even blacker” (1966a, 10). This blackening of Baraka’s work would accelerate in 1965, when he fled white bohemian culture and entered into a Black cultural nationalist period that lasted until 1974; Baraka’s centrality to the Black Arts Movement during this time cannot be overstated. Finally, his most recent radical break occurred when he repudiated Black cultural nationalism in his 1974 essay “Toward Ideological Clarity” and began instead to espouse revolutionary Marxism. Baraka henceforth understands Black liberation in a global context and targets not simply white culture but rather monopoly capitalism. His Marxist literature has continued to exhibit the formal innovation and generic hybridity found in earlier periods, but it is now grounded on a leftist revolutionary politics that invokes a global revolutionary subject. Given such variety in identities and commitments, it is unsurprising to find negotiations of subjectivity throughout all four periods. In many instances, those negotiations take the form of an introspective but fragmented or divided self, as in the transitional poem “An Agony. As Now” (1964): “I am inside someone / who hates me. I look / out from his eyes” (Baraka 1964, 15). Similarly, the chapter of The System of Dante’s Hell (1965)—Baraka’s first and, until 2000, only published novel—titled “The Eighth Ditch (Is Drama” portrays a seduction...

Noninvasive cardiac activation imaging of ventricular arrhythmias during drug-induced QT prolongation in the rabbit heart

Background: Persistent left superior vena cava (PLSVC) is a rare vascular variant which has potential of firing sources of atrial fibrillation (AF). We describe a paroxysmal AF case with sick sinus syndrome (SSS) eliminated with successful PV and PLSVC isolation using an electroanatomical approach in a patient with PLSVC. Case: A 61-year-old woman, with previous episodes of poorly tolerated paroxysmal atrial fibrillation with long sinus pause, was admitted for radiofrequency (RF) ablation. PLSVC was confirmed with pre-procedural 3D-CT. Before ablation we observed the arrhythmogenic veins of AF. After isoproterenol provocation (10 µg), AF firing spontaneously observed from left inferior PV. Thus we performed the circumferential PVI. After PVI, we reanalyzed the non-PV foci with same dose isoproterenol provocation and spontaneous AF was induced repeatedly. The earliest site of the initial beat of AF was lateral LA and CS distal. The multipolor ring catheter positioned in PLSVC and the potential of PLSVC clearly recorded. After the construction of PLSVC with CARTO, we performed the PLSVC isolation. The circumferential RF delivery (25 W, 30 ml/min irrigation) for the distal PLSVC at the level of LSPV needed complete electrical isolation between LA and PLSVC. After PLSVC isolation, neither firing nor APC was found with isoproterenol provocation. AF or syncope episode did not recur 3 months later.

Multiple four-wave mixing in optical fibers: 1.5–3.4-THz femtosecond pulse sources and real-time monitoring of a 20-GHz picosecond source

Despite recent advances in clinical electrophysiology, diagnosis of atrial tachycardia (AT) originating near Koch's triangle remains challenging. We sought a novel technique for rapid and accurate diagnosis of AT in the electrophysiologic laboratory. Sixty-two supraventricular tachycardias including 18 ATs (10 ATs arising from near Koch's triangle), 32 atrioventricular nodal reentrant tachycardias (AVNRTs), and 12 orthodromic reciprocating tachycardias (ORTs) were studied. Overdrive pacing during the tachycardia from different atrial sites was performed, and the maximal difference in the postpacing VA intervals (last captured ventricular electrogram to the earliest atrial electrogram of the initial beat after pacing) among the different pacing sites was calculated (delta-VA interval). The delta-VA intervals were >14 ms in all AT patients and <14 ms in all AVNRT/ORT patients, and thus, the delta-VA interval was diagnostic for AT with the sensitivity, specificity, and positive and negative predictive values all being 100%. When the diagnostic value of the delta-VA interval and conventional maneuvers were compared for differentiating AT from atypical AVNRT, both a delta-VA interval >14 ms and "atrial-atrial-ventricular" response after overdrive ventricular pacing during the tachycardia were diagnostic. However, the "atrial-atrial-ventricular" response criterion was available in only 52% of the patients because of poor ventriculoatrial conduction. The delta-VA interval was useful for diagnosing AT irrespective of patient conditions such as ventriculoatrial conduction.

Swimming in the sea hare Aplysia brasiliana: Cost of transport, parapodial morphometry, and swimming behavior

Electrophysiological characteristic of a patient exhibiting the short-coupled variant of torsade de pointes

The long-QT syndrome (LQTS) is an electrophysiological (EP) entity characterized by prolongation of cardiac repolarization and the occurrence of polymorphic ventricular tachyarrhythmias (VTs), sometimes with a twisting QRS morphology, better known as torsade de pointes (TdP). In the present study, detailed analysis of ventricular tridimensional activation patterns during nonsustained TdP VT was performed to provide an EP mechanism of the periodic transition in QRS axis. The studies were conducted with the anthopleurin-A canine model of LQTS. Tridimensional isochronal maps of ventricular activation were constructed from 256 bipolar electrograms obtained from the use of 64 plunge needle electrodes. In 26 episodes of nonsustained TdP VT, detailed activation maps could be accurately constructed during QRS-axis transitions in surface ECGs. The initial beat of all VTs consistently arose as a subendocardial focal activity, whereas subsequent beats were due to reentrant excitation in the form of rotating scrolls. The VT ended when reentrant excitation was terminated. In 22 of 26 episodes, the transition in QRS axis coincided with the transient bifurcation of a predominantly single rotating scroll into two simultaneous scrolls involving both the right ventricle and left ventricle separately. The common mechanism for initiation or termination of bifurcation was the development of functional conduction block between the anterior or posterior right ventricle free wall and the ventricular septum. In 4 of 26 episodes, a fast polymorphic VT, with an apparent shift in QRS axis, was due to a predominantly single localized circuit that varied its location and orientation from beat to beat, with the majority of ventricular myocardium being activated in a centrifugal pattern. The study provides for the first time an EP mechanism for the characteristic periodic transition of the QRS axis during TdP VT in the LQTS.

There has been debate regarding the level of sarcoplasmic reticulum (SR) Ca2+ ATPase protein in heart failure. We have used the SR Ca2+ ATPase inhibitor thapsigargin to investigate the functional contribution of this uptake system to contraction and relaxation in myocytes from failing and non-failing human ventricle. Myocytes were isolated from 28 failing and 18 non-failing ventricles and stimulated at 0.2 Hz, 32 degrees C in Krebs-Henseleit solution. Contraction amplitude and speed were compared before and after treatment with 1 mumol/l thapsigargin for 20 min to deplete SR Ca2+ stores. Initial beat duration was longer in myocytes from failing hearts. Addition of thapsigargin significantly prolonged the beat in myocytes from both groups, but the increase was greater in non-failing hearts (beat duration increased by 0.79 +/- 0.12 s in myocytes from non-failing hearts compared with 0.37 +/- 0.12 s in those from failing, P < 0.02). The contraction amplitude increased at high stimulation frequencies in myocytes from non-failing hearts (from 2.6% shortening at 0.1 Hz to 4.6% at 1 Hz, P < 0.001, n = 9), but not in those from failing hearts (1.8% at 0.1 Hz compared with 1.7% at 1 Hz, n = 5). Thapsigargin abolished the positive staircase in the non-failing, but had no effect in the failing group. Contraction amplitude following a rest interval was significantly depressed relative to steady-state levels in myocytes from the non-failing hearts (44.8 +/- 10.3% at 3 min), but not in failing (102 +/- 18%, P < 0.01 compared to non-failing at 3 min). Following thapsigargin treatment, there were no longer significant differences between failing and non-failing myocytes in the time course of the beat, frequency response or post-rest behaviour. The differences between myocytes from failing and non-failing hearts were reduced by inhibition of SR function. These results are consistent with the hypothesis that the initial differences had been due to decreased SR Ca2+ uptake.

We have previously developed a canine in vivo model of the long QT syndrome (LQTS) using the neurotoxin anthopleurin A (AP-A), which acts by slowing sodium channel inactivation. The recent discovery of a genetic mutation in the cardiac sodium channel in some patients with the congenital LQTS, resulting in abnormal gating behavior similar to sodium channels exposed to AP-A, provides a strong endorsement of this animal model as a valid surrogate to the clinical syndrome of LQTS. In the present study, we conducted high-resolution tridimensional isochronal mapping of both activation and repolarization patterns in puppies exposed to AP-A that developed LQTS and polymorphic ventricular tachyarrhythmias (VTs). To map repolarization, we measured activation-recovery intervals (ARIs) using multiple unipolar extracellular electrograms. We demonstrated, for the first time in vivo, the existence of spatial dispersion of repolarization in the ventricular wall and differences in regional recovery in response to cycle-length changes that were markedly exaggerated after AP-A administration. Analysis of tridimensional activation patterns showed that the initial beat of polymorphic VT consistently arose as focal activity from a subendocardial site, whereas subsequent beats were due to successive subendocardial focal activity, reentrant excitation, or a combination of both mechanisms. Reentrant excitation was due to infringement of a focal activity on the spatial dispersion of repolarization, resulting in functional conduction block and circulating wave fronts. The polymorphic QRS configuration of VT in the LQTS was due to either changing the site of origin of focal activity, resulting in varying activation patterns, or varying orientations of circulating wave fronts.

New experimental studies on the effects of large dynamic compressive loads on highly birefringent optical fibers are presented. The intensity rate of applied dynamic loads ranged between 2.18-6719 KN/m-sec. A Fibercore (previously York) HB600 Bow-Tie fiber with an initial beat length of 1.16 mm was employed in the present study. Sensor response is discussed in terms of the effects of force amplitudes and velocities on the calibration parameter T/sub f/. T/sub f/ is a function of the amplitude as well as the velocity of applied loading. Therefore, calibration of the sensor should be achieved through regression analysis of the load-fringe data for the entire spectrum of the desired force velocities. The ramification of this finding is that a single experiment for the measurement of T/sub f/ cannot provide the required parameters for calibration. This further implies that the change in beat length is also dependent on the amplitude and velocity of loading. The suggested method takes both effects into account through empirical analysis of experimental data.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Motility of fresh and aged halibut sperm

Rate dependence and adrenergic dependence of arrhythmias

The spiral orientation of left ventricular (LV) fibers suggests that twisting about the ventricular long axis of the apex with respect to the base, i.e., torsional deformation, may be characteristic of LV contraction. To demonstrate this twisting motion, 10 orthotopic human cardiac allograft recipients were studied with biplane cineradiography of tantalum helices implanted within the LV midwall at 12 specific sites. Counterclockwise twisting about the LV long axis (as reviewed from apex to base) accompanied ventricular ejection in all patients. Torsional deformation angles, measured relative to a reference minor axis at the base, were substantially smaller in the anteroapical wall, as compared with counterparts in the apical third of the inferior and lateral walls (anterior = 13.3 +/- 6.0 degrees, inferior = 18.7 +/- 6.3 degrees, and lateral = 23.4 +/- 10.7 degrees). Torsional angles at the midventricular level were roughly half as much and exhibited similar regional variabilities (anterior = 7.6 +/- 3.3 degrees, inferior = 9.0 +/- 3.3 degrees, lateral = 10.7 +/- 5.2 degrees, and septal = 8.8 +/- 3.8 degrees). Comparison of control beats and the initial beat after abrupt cessation of rapid atrial pacing (126 +/- 10 beats/min) with return to the control heart rate (96 +/- 9 beats/min) permitted the mild positive inotropic effect of tachycardia to be assessed at similar levels of ventricular load. Torsional deformation of the anteroapical and inferoapical sites increased significantly (p less than 0.05) over control values to 15.6 +/- 7.5 degrees and 21.2 +/- 5.5 degrees, respectively. In contrast, torsional deformation of the lateral wall was essentially unchanged. These data provide direct evidence for torsional deformation of the left ventricle in humans, demonstrate that torsion of the LV chamber is nonuniform, and suggest a dependence of LV torsion upon contractile strength that is attenuated in the lateral wall.

Particle transport velocity and ciliary beat frequency, at the level of a single cell of the epithelium, were measured simultaneously. The preparation used keeps the mucociliated epithelium of the frog palate functionally intact but is thin enough for light to be transmitted. The observations confirm that there exists a resting, or unstimulated, state of the epithelium in which the cilia do not beat. It is shown that tactile stimulation (contact with a small 50- to 75-microns foreign particle or with a fine wire probe) restarts ciliary beat. If the epithelium has not been depleted of its mucus, normal ciliary beat frequency is restored, and there is particle transport at the normal velocity. Only the cilia surrounding the moving particle in a patch about 10 times larger are beating at one time. Beat frequency is highest in the center of the patch, near the particle, and tapers to zero toward the edge. Mucus has to be present for particle transport to occur. Particles impacted on a depleted epithelium are not moved. The placement of previously collected endogenous mucus onto a depleted epithelium produces full ciliary activity and normal particle transport. The moving patch of beating cilia corresponds to a plaque of mucus surrounding the particle being transported. This plaque was produced upon first impact of the particle, presumably by mucus secretion, from the epithelial region which then surrounds it. Stimulation of a quiescent nondepleted epithelium with a wire probe induces a normal ciliary beat frequency that gradually decreases to zero. Stimulation by a wire probe of a mucus-depleted epithelium produces a level of initial beat frequency much below normal. Depletion of the epithelial preparation is by an episode of "creeping" over a glass surface. Depletion of the epithelium could be demonstrated histochemically. Analysis of the data of particle velocity and beat frequency is consistent with a wave-length of 45 microns for the metachronous wave.

Electrophysiologic observations on ventricular tachyarrhythmias following reperfusion