Minimal-memory realization of pearl-necklace encoders of general quantum convolutional codes

Quantum convolutional codes, like their classical counterparts, promise to offer higher error correction performance than block codes of equivalent encoding complexity, and are expected to find important applications in reliable quantum communication where a continuous stream of qubits is transmitted. Grassl and Roetteler devised an algorithm to encode a quantum convolutional code with a "pearl-necklace encoder." Despite their theoretical significance as a neat way of representing quantum convolutional codes, they are not well-suited to practical realization. In fact, there is no straightforward way to implement any given pearl-necklace structure. This paper closes the gap between theoretical representation and practical implementation. In our previous work, we presented an efficient algorithm for finding a minimal-memory realization of a pearl-necklace encoder for Calderbank-Shor-Steane (CSS) convolutional codes. This work extends our previous work and presents an algorithm for turning a pearl-necklace encoder for a general (non-CSS) quantum convolutional code into a realizable quantum convolutional encoder. We show that a minimal-memory realization depends on the commutativity relations between the gate strings in the pearl-necklace encoder. We find a realization by means of a weighted graph which details the non-commutative paths through the pearl-necklace. The weight of the longest path in this graph is equal to the minimal amount of memory needed to implement the encoder. The algorithm has a polynomial-time complexity in the number of gate strings in the pearl-necklace encoder.Comment: 16 pages, 5 figures; extends paper arXiv:1004.5179v

Unsteady natural convective power-law fluid flow past a vertical plate embedded in a non-Darcian porous medium in the presence of a homogeneous chemical reaction

A numerical solution is presented for unsteady coupled heat and mass transfer by natural convection from a non-Newtonian power-law fluid flow past a vertical plate embedded in a non-Darcian porous medium in the presence of viscous dissipation and chemical reaction effects. The governing equations are formulated and a numerical solution is obtained by using an explicit finite-difference scheme. The solutions at each time step have been found to reach the steady state solution properly. The numerical results are presented in tabular and graphical form to show the effects of material parameters of the problem on the solution

Preparation and spectroscopic studies of Hydroxyapatite embedded in Poly(N-Vinylpyrrolidone) matrix

Pure HAp powder was prepared by precipitation and HAp/PVP composites were prepared by casting technique. X-ray diffraction was performed to examine the crystallinity and the complexation between HAp and PVP when the amount of HAp increased. XRD and EDX analysis showed that the concentration 15 wt% is the most confirmation for the formation of HAp. SEM shows more than one form of HAp such as plates, needles and bundles in the morphological structure of pure HAp and 15 wt% of HAp. Two main weight loss regions and two peaks were observed in TGA and DSC thermograms that reveal reduction in the thermal stability of the prepared samples as HAp content increases. The activation energy of the films was decreased with increasing the concentration of HAp. DSC thermographs of the samples show that the values of the glass transition temperatures are decreased with increasing the content of HAp filler which suggest that HAp filler act as plasticizer. The conductivity–temperature plots show linear variation, which suggests an Arrhenius behavior. The conductivity increases with adding HAp content for low concentrations while decreased for the critical concentration (15 wt %) which confirms the XRD results

Can We Model Driver Perceptions? An In-Situ Experiment in Real-World Conditions

ABSTRACTIt is clear that perceptions play a significant role in traveler decisions. Consequently, traveler perceptions are a corner stone in the feasibility of traveler information systems; for traveler information systems are only valuable if the drivers are incapable of accurately acquiring the provided information on their own, and if the provided information is relevant for the drivers' decision criteria. Accuracy of traveler perceptions has been repeatedly researched in public transportation, and has been found to vary according to different reasons. However, in spite of the clear significance of traveler perceptions, minimal effort has been put into modeling it. Almost all travel behavior models are based on traveler experiences, which are assumed to reflect traveler perceptions via the addition of some random error component. This works introduces an alternative approach: instead of adding an error component to represent driver perceptions, it proposes to model driver perceptions. This work is based on a real-world route choice experiment of a sample of 20 drivers who made more than 2,000 real-world route choices. Each of the drivers' experiences, perceptions, and choices were recorded, analyzed and cross examined. The paper demonstrates that: i) driver experiences are different from driver perceptions, ii) driver perceptions explain driver choices better than driver experiences, iii) it is possible to model and predict driver perceptions of travel distance, time and speed

Effect of gamma irradiation doses and salting solutions (NaCl %) on the fumonisins (B1 &B2) of infected and row maize

The objectives of this investigation were to evaluate the effects and ability of gamma irradiation doses (4, 8 and 12 kGy) and salting solutions (7 %, 14% and 21% NaCl) to remove fumonisins (B1&B2) contaminated maize. Moreover, chemical and microbiological properties of maize affected by gamma irradiation doses were studied. The results indicated that: (i) there were not differences between non-irradiated and irradiated maize samples for its chemical composition; (ii)gamma rays had completely inactivated counts of total bacteria, molds and yeasts; (iii) a dose of 4, 8 and 12 kGy were sufficient for complete destruction of fumonisins infected maize; (iv) the fumonisins content in the row and deliberately infected maize decreased with the increasing concentration of  NaCl; and (v) the combination of gamma irradiation and NaCl solutions inhibited of fumonisins. It can be concluded that gamma irradiation and NaCl solutions can be used for detoxification of fumonisin-contaminated maize and improving its microbial loud. Keywords: Maize,Gamma irradiation, NaCl solution Mycotoxins, Fumonisin

Fundoplication in neurologically impaired children: Nissen or Thal?

Background/purpose Gastroesophageal reflex disease (GERD) is a highly prevalent problem in infants and children with severe neurological impairment (33–75%). It occurs in 44–67% of children undergoing antireflux surgery. This study is conducted to compare the results of fundoplication, according to the Nissen and Thal procedure for management of GERD in neurologically impaired children.Materials and methods Between May 2007 and January 2011, 69 neurologically impaired children with severe GERD underwent fundoplication (Nissen= 32, Thal= 37) with construction of a Stamm gastrostomy tube in 58 patients. The male-to-female ratio was 1.6 : 1; the mean age was 1.8 years. Preoperative workup of the patients included upper gastrointestinal tract contrast series, upper gastrointestinal tract endoscopy, and a 24-h pH study.Results Perinatal asphyxia was the most common cause of neurological impairment (30.4%). Feeding dysfunction represented the most common indication for surgery (52.2%). Recurrence of symptoms was found in 14 patients (20.3%); 10 patients (14.5%) died because of respiratory failure. Acid pH-metry showed a statistically significant difference between preoperative and postoperative data; however, this difference was insignificant on comparing the postoperative parameters of the Nissen fundoplication group with the Thal fundoplication group.Conclusion GERD in neurologically impaired children is a very common problem associated with a high failure rate after properly performed fundoplication. In our series, the outcome of Thal fundoplication showed an insignificant difference when compared with that of Nissen fundoplication with less dissection and less dysphagia or gas bloat. Long-term evaluation is needed as incidence of recurrence increases with time secondary to the persistent comorbidities. Further refinement of management strategies is required to decrease incidence of recurrence and to improve the overall quality of life. Keywords: fundoplication, gastroesophageal reflux disease, neurological impairmen