Pisa: Arbitration outsourcing for state channels

State channels are a leading approach for improving the scalability of blockchains and cryptocurrencies. They allow a group of distrustful parties to optimistically execute an application-defined program amongst themselves, while the blockchain serves as a backstop in case of a dispute or abort. This effectively bypasses the congestion, fees and performance constraints of the underlying blockchain in the typical case. However, state channels introduce a new and undesirable assumption that a party must remain online and synchronised with the blockchain at all times to defend against execution fork attacks. An execution fork can revert a state channel's history, potentially causing financial damage to a party that is innocent except for having crashed. To provide security even to parties that may go offline for an extended period of time, we present Pisa, the first protocol to propose an accountable third party who can be hired by parties to cancel execution forks on their behalf. To evaluate Pisa, we provide a proof-of-concept implementation for a simplified Sprites and we demonstrate that it is cost-efficient to deploy on the Ethereum network

Comparative evaluation of induction with propofol vs induction with sevoflurane for insertion of laryngeal mask airway in children

Background: There is increasing use of laryngeal mask airway in children because of ease of insertion and minimal disturbances in cardio respiratory system and lesser risk of airway injury during perioperative period as compared to endotracheal tube. It is also simple, well-tolerated, safe, reusable, cost effective method of airway management in paediatric patients. Intravenous propofol (1%) is a preferred induction agent for LMA insertion till date, while sevoflurane, a halogenated volatile inhalational, non-irritating anaesthetist agent with pleasant odour is also suitable for inhalational induction of children. This study was carried out to study and compare clinical efficacy of propofol and sevoflurane for laryngeal mask airway (LMA) insertion in children undergoing short surgical procedures.Methods: In this study, total 100 children of ASA grade I/II of either sex with age group 3-8 years, weighing between 10-20 kg were enrolled. They were induced with either sevoflurane (group S) or intravenous propofol (group P) 3 mg/kg. Then appropriate size LMA was inserted. Various parameters like jaw relaxation and ease of insertion attempts required hemodynamic changes were noted and compared in two groups.Results: In group P, 94% patients and groups S, 90% patients had full jaw relaxation. The LMA insertion was easy in 98% patients in groups P and 94% patients in groups S. In 98% patients of groups P and 96% patients in groups S, LMA was inserted successfully in first attempt. The mean time required for LMA insertion was 19.16±5.29 seconds in groups P and 20.8±6.39 seconds in groups S. Both the groups were comparable with respect to haemodynamic changes observed which were transient and clinically not significant though statically significant.Conclusions: Both the groups showed comparable and satisfactory LMA insertion conditions, hence both can be routinely used for induction of anaesthesia in children

Parallel algorithm with spectral convergence for nonlinear integro-differential equations

We discuss a numerical algorithm for solving nonlinear integro-differential equations, and illustrate our findings for the particular case of Volterra type equations. The algorithm combines a perturbation approach meant to render a linearized version of the problem and a spectral method where unknown functions are expanded in terms of Chebyshev polynomials (El-gendi's method). This approach is shown to be suitable for the calculation of two-point Green functions required in next to leading order studies of time-dependent quantum field theory.Comment: 15 pages, 9 figure

The Impact of Lesion In-Painting and Registration Methods on Voxel-Based Morphometry in Detecting Regional Cerebral Gray Matter Atrophy in Multiple Sclerosis

Background and Purpose: VBM has been widely used to study GM atrophy in MS. MS lesions lead to segmentation and registration errors that may affect the reliability of VBM results. Improved segmentation and registration have been demonstrated by WM LI before segmentation. DARTEL appears to improve registration versus the USM. Our aim was to compare the performance of VBM-DARTEL versus VBM-USM and the effect of LI in the regional analysis of GM atrophy in MS. Materials and Methods: 3T T1 MR imaging scans were acquired from 26 patients with RRMS and 28 age-matched NC. LI replaced WM lesions with normal-appearing WM intensities before image segmentation. VBM analysis was performed in SPM8 by using DARTEL and USM with and without LI, allowing the comparison of 4 VBM methods (DARTEL + LI, DARTEL − LI, USM + LI, and USM − LI). Accuracy of VBM was assessed by using NMI, CC, and a simulation analysis. Results: Overall, DARTEL + LI yielded the most accurate GM maps among the 4 methods (highest NMI and CC, P < .001). DARTEL + LI showed significant GM loss in the bilateral thalami and caudate nuclei in patients with RRMS versus NC. The other 3 methods overestimated the number of regions of GM loss in RRMS versus NC. LI improved the accuracy of both VBM methods. Simulated data suggested the accuracy of the results provided from patient MR imaging analysis. Conclusions: We introduce a pipeline that shows promise in limiting segmentation and registration errors in VBM analysis in MS

Renormalization of initial conditions and the trans-Planckian problem of inflation

Understanding how a field theory propagates the information contained in a given initial state is essential for quantifying the sensitivity of the cosmic microwave background to physics above the Hubble scale during inflation. Here we examine the renormalization of a scalar theory with nontrivial initial conditions in the simpler setting of flat space. The renormalization of the bulk theory proceeds exactly as for the standard vacuum state. However, the short distance features of the initial conditions can introduce new divergences which are confined to the surface on which the initial conditions are imposed. We show how the addition of boundary counterterms removes these divergences and induces a renormalization group flow in the space of initial conditions.Comment: 22 pages, 4 eps figures, uses RevTe

Study of biochemical markers in iron deficiency anemia

Background: The present study was aimed to study alterations in levels of oxidants and antioxidants in iron deficiency anemia (IDA).Methods: 30 patients of IDA in age group of 20-50 and 30 healthy subjects were included for study. Serum Iron, TIBC &amp; Hb% were estimated to diagnose IDA. Serum Malondialdehyde (MDA), Nitric oxide (NO) as an oxidants &amp; Superoxide dismutase (SOD), vitamin E, vitamin C, Zinc (Zn) levels as antioxidants were estimated.Results: Significant decreased levels of Hb%, serum iron, SOD, Vitamin C, vitamin E, Zn were found. TIBC, MDA, NO were significantly increased as compared to controls.Conclusion: The normal adult erythrocytes can resist oxidative stress by several antioxidant defense systems. In IDA, oxidative stress causes lipid peroxidation and membrane damage. So antioxidants can be used as a marker for prevention of membrane damage due to oxidative stress

TxProbe: Discovering Bitcoin’s Network Topology Using Orphan Transactions

Bitcoin relies on a peer-to-peer overlay network to broadcast transactions and blocks. From the viewpoint of network measurement, we would like to observe this topology so we can characterize its performance, fairness and robustness. However, this is difficult because Bitcoin is deliberately designed to hide its topology from onlookers. Knowledge of the topology is not in itself a vulnerability, although it could conceivably help an attacker performing targeted eclipse attacks or to deanonymize transaction senders. In this paper we present TxProbe, a novel technique for reconstructing the Bitcoin network topology. TxProbe makes use of peculiarities in how Bitcoin processes out of order, or “orphaned” transactions. We conducted experiments on Bitcoin testnet that suggest our technique reconstructs topology with precision and recall surpassing 90%. We also used TxProbe to take a snapshot of the Bitcoin testnet in just a few hours. TxProbe may be useful for future measurement campaigns of Bitcoin or other cryptocurrency networks

Study of serum sodium and potassium concentration in cataract patients

Background: The present study was aimed to study alterations in levels of sodium and potassium in age-related cataract patients.Methods: 50 senile cataract patients in age group of 50 to 80 years and 50 control group were included for the study. Serum sodium and potassium levels were determined by flame photometry.Results: Significant (<0.0001)  increased levels of plasma Na+ in cataract patients (145.06 ± 5.84mEq/lit) were found as compared with controls (141.18 ± 2.67mEq/lit). While Plasma K+ the conc. in cataract patients (4.18 ± 0.34mEq/lit) was not significantly (P = 0.002) increased when compared with controls (4.13 ± 0.32mEq/lit).Conclusion: Na, K-ATPase is responsible for maintaining the correct concentrations of sodium and potassium in lens cells. In ageing, lens fibers undergoes oxidation, and glycation may decrease Na, K-ATPase activity. The asymmetrical distribution of Na, K-ATPase activity in the epithelium and fibers may contribute to ionic currents that flow in and around the lens. So, abnormal elevation of lens sodium can be used as a marker in the opacification of the lens cortex in age-related human cataract

Holographic Construction of Excited CFT States

We present a systematic construction of bulk solutions that are dual to CFT excited states. The bulk solution is constructed perturbatively in bulk fields. The linearised solution is universal and depends only on the conformal dimension of the primary operator that is associated with the state via the operator-state correspondence, while higher order terms depend on detailed properties of the operator, such as its OPE with itself and generally involve many bulk fields. We illustrate the discussion with the holographic construction of the universal part of the solution for states of two dimensional CFTs, either on $R \times S^1$ or on $R^{1,1}$. We compute the 1-point function both in the CFT and in the bulk, finding exact agreement. We comment on the relation with other reconstruction approaches.Comment: 26 pages, 4 figures, v2: comments adde

Time evolution of the chiral phase transition during a spherical expansion

We examine the non-equilibrium time evolution of the hadronic plasma produced in a relativistic heavy ion collision, assuming a spherical expansion into the vacuum. We study the $O(4)$ linear sigma model to leading order in a large-$N$ expansion. Starting at a temperature above the phase transition, the system expands and cools, finally settling into the broken symmetry vacuum state. We consider the proper time evolution of the effective pion mass, the order parameter $\langle \sigma \rangle$, and the particle number distribution. We examine several different initial conditions and look for instabilities (exponentially growing long wavelength modes) which can lead to the formation of disoriented chiral condensates (DCCs). We find that instabilities exist for proper times which are less than 3 fm/c. We also show that an experimental signature of domain growth is an increase in the low momentum spectrum of outgoing pions when compared to an expansion in thermal equilibrium. In comparison to particle production during a longitudinal expansion, we find that in a spherical expansion the system reaches the ``out'' regime much faster and more particles get produced. However the size of the unstable region, which is related to the domain size of DCCs, is not enhanced.Comment: REVTex, 20 pages, 8 postscript figures embedded with eps