279,339 research outputs found
Congenital heart block associated with Sjögren syndrome: case report
No full textBackground: Congenital heart block is a rare complication of pregnancy associated with Sjögren Syndrome that may result in the death of the foetus or infant, or the need for pacing in the newborn or at a later stage.Case report: The case is presented of a 64-year-old patient with primary Sjögren Syndrome and a history of having given birth to two sons with congenital heart block, both of whom required pacing several years later.Conclusion: The literature relating to this association is discussed including the suggested mechanism, long-term outcome of mothers of children with congenital heart block and preventive treatment strategies
Price Impact of Block Trades and Price Behavior Surrounding Block Trades in Indian Capital Market
No full textWe analyze the permanent (information effect) and temporary (liquidity effect) impact of block trades transacted in the National Stock Exchange of India. Block trades are identified using multiple criteria based on trade value and trade volume. Overall, the permanent price impact is more for block purchases than for block sales indicating that block purchases are more informative than block sales, which may be motivated by liquidity need. Unlike in other markets, we observe that the temporary impact is greater than the permanent impact in case of block purchase. We classify the block trades as All-or-None (AON) and Not-AON trades depending on the number of transactions through which a block order is executed. As expected, the price impact is higher for Not-AON trades as compared to AON trades (which can be assumed to be pre-negotiated trades). Further, arrival of multiple block trades increases market confidence on the information. The permanent price impact is higher for days where there are more than one block trade of similar nature than for days with only one block trade. To analyze the speed of market response to the information associated with block trades, we have used the ‘transaction time event approach’, as used by Holthausen et al. (1990). We find that the prices start increasing (front running) 8 minutes before block purchases but not in case of block sales i.e. some information about the impending block purchase is factored in by the market when the block trade is for purchases. Further, in the case of block sales, prices revert quickly leaving very small permanent price impact.
Teaching in the block: perceptions from an agricultural education classroom
No full textPlan BA relatively new initiative called block scheduling is being used in high schools all over the country. Several schools are investigating and adopting block schedules to replace traditional schedules. Block scheduling has several benefits to educators, for example, the larger blocks of class time allow for a variety of teaching methods and activities. The purpose of the study was to research the teachers' attitudes of the effectiveness of block scheduling design. The study focused on four questions (1) What are agricultural education teachers' perceptions of the overall effectiveness of block scheduling? (2) Have teaching methods in agricultural education changed in response to block scheduling? (3) Has enrollment in agriculture classes changed as a result of the block schedule? (4) What are important benefits and drawbacks of block scheduling specific to agricultural education classrooms? Surveys were distributed to Wisconsin Agricultural Education Instructors at the end of the 2002 school year. The survey consisted of demographic information, 30 Likert type items, and a comment section. A total of 48 surveys were mailed to participants and thirty-two (67%) were returned. Results show that many teachers feel overall that block scheduling is effective for their agricultural education programs. Many participants stated advantages to block scheduling such as hands-on and lab activities, more time for fieldtrips, and the opportunity to have more individualized contact with students. However, participants also mentioned disadvantages such as challenges with FFA recruitment and member involvement
Price impact of block trades in the Saudi stock market
No full textThis paper examines the price impact of block trades for the 124 companies that comprise all listed firms in the Saudi stock market (SSM). We use high frequency intraday data (one minute intervals) for the period 2005-2008 to provide out of sample evidence of the determinants of price impact. We find an asymmetric price impact of 0.5% for block purchases and -0.38% for block sales. We document a price continuation post block trades and a price reversal after block sales. Sellers of block trades in the Saudi market pay higher liquidity premiums than
buyers of block trades. However, on average, the price effect of a block trade is small and short-lived suggesting that resiliency is high in the market. Moreover, we find a direct relationship between the size of the trades and the level of information asymmetry in the market. Despite the structural differences of the SSM, the intraday pattern of price impacts is similar to patterns documented in other markets, namely an inverse J-shaped pattern. Finally,
sophisticated traders can gain abnormal profits in the SSM through “free riding”, a trader can benefit from the overreaction before the block trade and price reversal after the block trade
Adaptive-rate techniques for frequency-hop multiple-access packet-radio networks
No full textThe effects of adaptive-rate transmissions and routing on the total throughput of a slow-frequency-hop packet-radio network are considered. Adaptive rates are achieved through the use of error-control coding with perfect side information. Both fixed-length codes and variable-length codes are considered. Performance results are obtained for direct transmission (i.e., no routing), two-hop limited routing, and full routing. Each link metric is a function of the amount of interference caused by using the link. We compare the total network throughput for each of these schemes with both fixed-rate and adaptive-rate coding.United States. Dept. of the Air Force (FA8721-05-C-0002
Teachers' perceptions of the block schedule
No full textPlan BThis study was developed to investigate Menomonie High School teachers’ perceptions of the block schedule regarding modifications to departmental courses and services, advantages and disadvantages of the block schedule, and suggestions for modifications to the current block schedule. A researcher-developed questionnaire was sent via school mailbox to 66 faculty, with 28 returning the questionnaire and participating in the study. The findings indicate that modifications made to departmental courses and services included: the compacting of curriculum, the addition of terms to some courses, the inclusion of additional grade levels in some courses, and the creation of new courses. The advantages that were indicated included: longer class time allowed for more in-depth discovery type learning, varied teaching practices and activities, integration of content areas such as U.S. history/U.S. literature and speech/composition, fewer teacher preparations, longer preparation time, fewer courses for students to manage, less stress for teachers and students, improved relationships between students and teachers, and the creation of new elective course offerings. The disadvantages indicated included: less developmental time for learning, an increase in class sizes, some curriculum lost due to compacting, some departments could not service all student requests, some departments dropped electives to accommodate more sections of required courses, no safety net for failing students, difficulty of placing transfer students in the schedule, class balances unequally distributed, some students had difficulty maintaining attention for the longer period of time, retention loss during gaps between related courses, curriculum watered down due to necessary review time, difficulties for substitute teachers, no study halls for remediation, and student absences are more detrimental. Suggestions for modifying the current block schedule included: going to a trimester schedule with twelve or thirteen week grading terms and five sixty to sixty-five minute periods, increasing staff, modifying the block with skinnies, implementing an A/B block schedule, adding electives in all areas, keeping students with the same teacher for all terms of a course, building in more one on one time for students who are failing, and having three terms for lower level courses
Automated design of a lightweight block cipher with Genetic Programming
No full textIn this paper, we present a general framework for the automated design of cryptographic block ciphers by using Genetic Programming. We evolve highly nonlinear and extremely efficient functions that can be used as core components of any cryptographic construction. As an example, a new block cipher named Raiden is proposed. We present a preliminary security analysis of our proposal and a comparison in terms of performance with similar block ciphers such as TEA. The results show that automatically-obtained schemes, such as the one presented here, could be competitive both in security and speed
Acquired heart block: A possible complication of patent ductus arteriosus in a preterm infant
No full textA large patent ductus arteriosus (PDA) is a frequently encountered clinical problem in extremely low birth weight (ELBW) infants. It leads to an increased pulmonary blood flow and in a decreased or reversed diastolic flow in the systemic circulation, resulting in complications. Here we report a possible complication of PDA not previously published. On day 8 of life, a male ELBW infant (birth weight 650 g) born at a gestational age of 23 weeks and 3 days developed an atrioventricular block (AV block). The heart rate dropped from 168/min to 90/min, and the ECG showed a Wenckebach second-degree AV block and intraventricular conduction disturbances. Echocardiography demonstrated a PDA with a large left-to-right shunt and large left atrium and left ventricle with high contractility. Within several minutes after surgical closure of the PDA, the heart rate increased, and after 30 min the AV block had improved to a 1: 1 conduction ratio. Echocardiography after 2 h revealed a significant decrease of the left ventricular and atrial dimensions. Within 12 h, the AV block completely reversed together with the intraventricular conduction disturbances. We suggest that PDA with a large left-to-right shunt and left ventricular volume overload may lead to an AV block in an ELBW infant. Surgical closure of the PDA may be indicated. Copyright (C) 2007 S. Karger AG, Basel
Modeling Building Block Interdependency
No full textThe Building-Block Hypothesis appeals to the notion of problem decomposition and the assembly of solutions from sub-solutions. Accordingly, there have been many varieties of GA test problems with a structure based on building-blocks. Many of these problems use deceptive fitness functions to model interdependency between the bits within a block. However, very few have any model of interdependency between building-blocks; those that do are not consistent in the type of interaction used intra-block and inter-block. This paper discusses the inadequacies of the various test problems in the literature and clarifies the concept of building-block interdependency. We formulate a principled model of hierarchical interdependency that can be applied through many levels in a consistent manner and introduce Hierarchical If-and-only-if (H-IFF) as a canonical example. We present some empirical results of GAs on H-IFF showing that if population diversity is maintained and linkage is tight then the GA is able to identify and manipulate building-blocks over many levels of assembly, as the Building-Block Hypothesis suggests
A Block ILUT Smoother for Multipatch Geometries in Isogeometric Analysis
No full textSince its introduction in [20], Isogeometric Analysis (IgA) has established itself as a viable alternative to the Finite Element Method (FEM). Solving the resulting linear systems of equations efficiently remains, however, challenging when high-order B-spline basis functions of order p> 1 are adopted for approximation. The use of Incomplete LU (ILU) type factorizations, like ILU(k) or ILUT, as a preconditioner within a Krylov method or as a smoother within a multigrid method is very effective, but costly [37]. In this paper, we investigate the use of a block ILUT smoother within a p-multigrid method, where the coarse grid correction is obtained at p= 1, and compare it to a global ILUT smoother in case of multipatch geometries. A spectral analysis indicates that the use of the block ILUT smoother improves the overall convergence rate of the resulting p-multigrid method. Numerical results, obtained for a variety of two dimensional benchmark problems, illustrate the potential of this block ILUT smoother for multipatch geometries.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Numerical Analysi
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