Fake Z

Recently introduced connections between quantum codes and Narain CFTs provide a simple ansatz to express a modular-invariant function $Z(\tau,\bar \tau)$ in terms of a multivariate polynomial satisfying certain additional properties. These properties include algebraic identities, which ensure modular invariance of $Z(\tau,\bar \tau)$, and positivity and integrality of coefficients, which imply positivity and integrality of the $\mathfrak{u}(1)^n \times \mathfrak{u}(1)^n$ character expansion of $Z(\tau,\bar \tau)$. Such polynomials come naturally from codes, in the sense that each code of a certain type gives rise to the so-called enumerator polynomial, which automatically satisfies all necessary properties, while the resulting $Z(\tau,\bar \tau)$ is the partition function of the code CFT -- the Narain theory unambiguously constructed from the code. Yet there are also ``fake'' polynomials satisfying all necessary properties, that are not associated with any code. They lead to $Z(\tau,\bar \tau)$ satisfying all modular bootstrap constraints (modular invariance and positivity and integrality of character expansion), but whether they are partition functions of any actual CFT is unclear. We consider the group of the six simplest fake polynomials and denounce the corresponding $Z$'s as fake: we show that none of them is the torus partition function of any Narain theory. Moreover, four of them are not partition functions of any unitary 2d CFT; our analysis for other two is inconclusive. Our findings point to an obvious limitation of the modular bootstrap approach: not every solution of the full set of torus modular bootstrap constraints is due to an actual CFT. In the paper we consider six simple examples, keeping in mind that thousands more can be constructed.Comment: 30 page

Propagated repolarization of simulated action potentials in cardiac muscle and smooth muscle

BACKGROUND: Propagation of repolarization is a phenomenon that occurs in cardiac muscle. We wanted to test whether this phenomenon would also occur in our model of simulated action potentials (APs) of cardiac muscle (CM) and smooth muscle (SM) generated with the PSpice program. METHODS: A linear chain of 5 cells was used, with intracellular stimulation of cell #1 for the antegrade propagation and of cell #5 for the retrograde propagation. The hyperpolarizing stimulus parameters applied for termination of the AP in cell #5 were varied over a wide range in order to generate strength / duration (S/D) curves. Because it was not possible to insert a second "black box" (voltage-controlled current source) into the basic units representing segments of excitable membrane that would allow the cells to respond to small hyperpolarizing voltages, gap-junction (g.j.) channels had to be inserted between the cells, represented by inserting a resistor (R(gj)) across the four cell junctions. RESULTS: Application of sufficient hyperpolarizing current to cell #5 to bring its membrane potential (V(m)) to within the range of the sigmoidal curve of the Na(+ )conductance (CM) or Ca(++ )conductance (SM) terminated the AP in cell #5 in an all-or-none fashion. If there were no g.j. channels (R(gj )= ∞), then only cell #5 repolarized to its stable resting potential (RP; -80 mV for CM and -55 mV for SM). The positive junctional cleft potential (V(JC)) produced only a small hyperpolarization of cell #4. However, if many g.j. channels were inserted, more hyperpolarizing current was required (for a constant duration) to repolarize cell #5, but repolarization then propagated into cells 4, 3, 2, and 1. When duration of the pulses was varied, a typical S/D curve, characteristic of excitable membranes, was produced. The chronaxie measured from the S/D curve was about 1.0 ms, similar to that obtained for muscle membranes. CONCLUSIONS: These experiments demonstrate that normal antegrade propagation of excitation can occur in the complete absence of g.j. channels, and therefore no low-resistance pathways between cells, by the electric field (negative V(JC)) developed in the narrow junctional clefts. Because it was not possible to insert a second black-box into the basic units that would allow the cells to respond to small hyperpolarizing voltages, only cell #5 (the cell injected with hyperpolarizing pulses) repolarized in an all-or-none manner. But addition of many g.j. channels allowed repolarization to propagate in a retrograde direction over all 5 cells

Dynamic Annotation of Search Results from Web Databases

The Internet provides a great extent of beneficial knowledge which is usually formatted for its users, which makes it troublesome to extract relevant data from diverse sources. The World Wide Web plays a major role as all kinds of information repository and has been very success full in disseminating information to users. For the encoded data units to be machine process able, which is essential for many applications such as deep web data collection and internet comparison shopping, they need to be extracted out and allot meaningful labels. This paper deals with the automatic annotation of Search result records from the multiple web databases. Search result presents an automatic annotation approach that first aligns the data units on a result page into different groups such that the data in the same group have the same semantic. Then for each group annotate it from different aspects and aggregate the different annotations to predict a final annotation label for it. Finally wrapper is automatically generated by the automatic tag matching weight method. DOI: 10.17762/ijritcc2321-8169.15070

Boundary effects influence velocity of transverse propagation of simulated cardiac action potentials

BACKGROUND: We previously demonstrated that transverse propagation of excitation (cardiac action potentials simulated with PSpice) could occur in the absence of low-resistance connections (gap – junction channels) between parallel chains of myocardial cells. The transverse transmission of excitation between the chains was strongly dependent on the longitudinal resistance of the interstitial fluid space between the chains: the higher this resistance, the closer the packing of the parallel chains within the bundle. The earlier experiments were carried out with 2-dimensional sheets of cells: 2 × 3, 3 × 4, and 5 × 5 models (where the first number is the number of parallel chains and the second is the number of cells in each chain). The purpose of the present study was to enlarge the model size to 7 × 7, thus enabling the transverse velocities to be compared in models of different sizes (where all circuit parameters are identical in all models). This procedure should enable the significance of the role of edge (boundary) effects in transverse propagation to be determined. RESULTS: It was found that transverse velocity increased with increase in model size. This held true whether stimulation was applied to the entire first chain of cells or only to the first cell of the first chain. It also held true for retrograde propagation (stimulation of the last chain). The transverse resistance at the two ends of the bundle had almost no effect on transverse velocity until it was increased to very high values (e.g., 100 or 1,000 megohms). CONCLUSION: Because the larger the model size, the smaller the relative edge area, we conclude that the edge effects slow the transverse velocity

Tomographic imaging with an LED-based photoacoustic-ultrasound system

Combined Photoacoustic (PA) and Ultrasound (US) imaging systems are finding more preclinical and clinical applications. However, majority of the commercial systems use expensive pulsed lasers. In most small animal studies and clinical applications like arthritis screening of finger joints, there is a need for tomographic imaging. In this work, we present PA and US tomographic imaging using a commercial imaging system with LED arrays as illumination source. We employ multiangle spatial compounding of PA and US images using a probe with a linear array transducer and four LED arrays, to form dual-mode tomographic images. Using phantom experiments, the proposed approach is validated and thoroughly tested. Further, the potential of the system is demonstrated by imaging knee joint and abdominal region of a mouse. This proposed approach has several advantages. First, the resolution and signal to noise ratio (SNR) are improved with the compounding of images from multiple angles. The resolution improvement owes to better axial resolution compared to lateral and high SNR with averaging. Secondly, the limited view artifacts and loss of information from the use of a linear array US probe is tackled. The US tomographic images of the mouse-knee RA model show structural details of the joint and blood vessels were visible in the tomographic PA images. The whole animal images enabled improved functional and structural information. An affordable PA/US tomographic imaging system with potential in clinical arthritis-screening and small animal imaging is presented.</p

Minimally invasive photoacoustic imaging for device guidance and monitoring of radiofrequency ablation

Radiofrequency ablation (RFA) procedures for liver cancer treatment are hindered by high tumor recurrence. This is thought to be due to the intrinsic limitation of the heating mechanism and insufficient real-time feedback from imaging modalities. Most RFA procedures are performed under ultrasound (US) imaging and there are limitations in accurate device guidance and ablation monitoring. We propose photoacoustic (PA) imaging as a potential add-on to US imaging to address these limitations. Specifically, we present two interstitial PA imaging methods. Firstly, an annular fiber probe that can encapsulate an RFA device in its lumen. This device enables RFA device guidance, visualization of major blood vessels and targeting tumor tissue. Secondly, we used a cylindrical diffuser-based interstitial illumination to differentiate coagulated and native tissue. We present our results on RFA device guidance and ablation visualization using these approaches. The contrast provided by PA imaging for RFA needle and multiple electrodes is compared against that of US images. The difference between coagulated and native ex vivo liver tissue using PA imaging is studied. Finally, we propose a protocol to incorporate the minimally invasive PA imaging for the clinical RFA procedures. We would like to conclude with a note on how the proposed approach can potentially improve the outcome of RFA procedures.</p