512 research outputs found

    Structural aspects of local adjunct languages

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    Several open problems concerning local adjunct languages are considered and solved. One of the most interesting (from a linguistic point of view) and difficult (mathematically) open problems was whether or not null symbols can be dispensed without sacrificing the weak generative capacity. This problem is solved and the answer is negative.Also considered are some problems concerning one-sided grammars, homomorphisms of languages (it is shown that local adjunct languages are not closed under homomorphism), β-linear languages and mixed adjunct grammars

    Local constraints in programming languages part I: syntax

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    AbstractThe method of local constraints attempts to describe context-free languages in an apparently context-sensitive form which helps to retain the intuitive insights about the grammatical structure. This form of description, while apparently context-sensitive is, in fact, context-free and allows a program derivation structure to be represented as a tree with additional constraints, thus allowing for the possibility of a correctness proof in the form of Knuthian semantics. These semantic aspects will be discussed in a sequel to this paper (Part II: Semantics). Several detailed examples are given to motivate the use of local constraints grammars including some examples from the syntax of ALGOL 60. A parsing algorithm has been described; its purpose is to show that the computation of local constraints is quite reasonable. Transformation rules for transferring a context-free grammar into a local constraints grammar have been described and some heuristic approaches for the inverse transformation have been presented

    Tree adjunct grammars

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    In this paper, a tree generating system called a tree adjunct grammar is described and its formal properties are studied relating them to the tree generating systems of Brainerd (Information and Control 14 (1969), 217–231) and Rounds (Mathematical Systems Theory 4 (1970), 257–287) and to the recognizable sets and local sets discussed by Thatcher (Journal of Computer and System Sciences 1 (1967), 317–322; 4 (1970), 339–367) and Rounds. Linguistic relevance of these systems has been briefly discussed also

    CHALLENGES AND TECHNIQUES OF MOTHERS HAVING CHILDREN DIAGNOSED WITH ATTENTION DEFICIT HYPERACTIVITY DISORDER (ADHD): BASIS FOR A RESOURCE GUIDE

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    The enormous and continuing challenge encounter by mothers in handling their children with Attention Deficit Hyperactivity (ADHD) inspired the progress and ultimate result of this study. A qualitative case study method extracted the result of this study. Further, this study identified the challenges as well as the strategies employ by mothers having children with ADHD. There were ten mothers interviewed, their respective husbands and the significant  others to triangulate the data. Results of this study proved that mothers are experiencing different challenges in handling their children with ADHD such as emotional, physical, financial, time management and in disciplining their child. Strategies by mothers were likewise identified in this study such as having a support system from their friends, families and association of their affiliation; consulting professionals for medication or treatment, practiced religiosity, acceptance of the reality, open communication with the husband, implementing discipline recommended by the professionals and eating. Results of this study prove that mothers having children with ADHD need help in handling their children. Thus, a structured resource guide  is necessary to empower the mothers and obtain a quality life amidst the challenge they are experiencing

    A Field Trial of Alternative Targeted Screening Strategies for Chagas Disease in Arequipa, Peru

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    In the wake of emerging T. cruzi infection in children of periurban Arequipa, Peru, we conducted a prospective field trial to evaluate alternative targeted screening strategies for Chagas disease across the city. Using insect vector data that is routinely collected during Ministry of Health insecticide application campaigns in 3 periurban districts of Arequipa, we separated into 4 categories those households with 1) infected vectors; 2) high vector densities; 3) low vector densities; and 4) no vectors. Residents of all infected-vector households and a random sample of those in the other 3 categories were invited for serological screening for T. cruzi infection. Subsequently, all residents of households within a 15-meter radius of detected seropositive individuals were invited to be screened in a ring case-detection scheme. Of 923 participants, 21 (2.28%) were seropositive. There were no significant differences in prevalence across the 4 screening strategies, indicating that household entomologic factors alone could not predict the risk of infection. Indeed, the most predictive variable of infection was the number of years a person lived in a location with triatomine insects. Therefore, a simple residence history questionnaire may be a useful screening tool in large, diverse urban environments with emerging Chagas disease

    Identification by PCR of Non-typhoidal Salmonella enterica Serovars Associated with Invasive Infections among Febrile Patients in Mali

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    The genus Salmonella has more than 2500 serological variants (serovars), such as Salmonella enterica serovar Typhi and Salmonella Paratyphi A and B, that cause, respectively, typhoid and paratyphoid fevers (enteric fevers), and a large number of non-typhoidal Salmonella (NTS) serovars that cause gastroenteritis in healthy hosts. In young infants, the elderly and immunocompromised hosts, NTS can cause severe, fatal invasive disease. Multiple studies of pediatric patients in sub-Saharan Africa have documented the important role of NTS, in particular Salmonella Typhimurium and Salmonella Enteritidis (and to a lesser degree Salmonella Dublin), as invasive bacterial pathogens. Salmonella spp. are isolated from blood and identified by standard microbiological techniques and the serovar is ascertained by agglutination with commercial antisera. PCR-based typing techniques are becoming increasingly popular in developing countries, in part because high quality typing sera are difficult to obtain and expensive and H serotyping is technically difficult. We have developed a series of polymerase chain reactions (PCRs) to identify Salmonella Typhimurium and variants, Salmonella Enteritidis and Salmonella Dublin. We successfully identified 327 Salmonella isolates using our multiplex PCR. We also designed primers to detect Salmonella Stanleyville, a serovar found in West Africa. Another PCR generally differentiated diphasic Salmonella Typhimurium and monophasic Salmonella Typhimurium variant strains from other closely related strains. The PCRs described here will enable more laboratories in developing countries to serotype NTS that have been isolated from blood

    Acute Beneficial Hemodynamic Effects of a Novel 3D-Echocardiographic Optimization Protocol in Cardiac Resynchronization Therapy

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    Post-implantation therapies to optimize cardiac resynchronization therapy (CRT) focus on adjustments of the atrio-ventricular (AV) delay and ventricular-to-ventricular (VV) interval. However, there is little consensus on how to achieve best resynchronization with these parameters. The aim of this study was to examine a novel combination of doppler echocardiography (DE) and three-dimensional echocardiography (3DE) for individualized optimization of device based AV delays and VV intervals compared to empiric programming.25 recipients of CRT (male: 56%, mean age: 67 years) were included in this study. Ejection fraction (EF), the primary outcome parameter, and left ventricular (LV) dimensions were evaluated by 3DE before CRT (baseline), after AV delay optimization while pacing the ventricles simultaneously (empiric VV interval programming) and after individualized VV interval optimization. For AV delay optimization aortic velocity time integral (AoVTI) was examined in eight different AV delays, and the AV delay with the highest AoVTI was programmed. For individualized VV interval optimization 3DE full-volume datasets of the left ventricle were obtained and analyzed to derive a systolic dyssynchrony index (SDI), calculated from the dispersion of time to minimal regional volume for all 16 LV segments. Consecutively, SDI was evaluated in six different VV intervals (including LV or right ventricular preactivation), and the VV interval with the lowest SDI was programmed (individualized optimization).EF increased from baseline 23±7% to 30±8 (p<0.001) after AV delay optimization and to 32±8% (p<0.05) after individualized optimization with an associated decrease of end-systolic volume from a baseline of 138±60 ml to 115±42 ml (p<0.001). Moreover, individualized optimization significantly reduced SDI from a baseline of 14.3±5.5% to 6.1±2.6% (p<0.001).Compared with empiric programming of biventricular pacemakers, individualized echocardiographic optimization with the integration of 3-dimensional indices into the optimization protocol acutely improved LV systolic function and decreased ESV and can be used to select the optimal AV delay and VV interval in CRT

    Neuroinflammation, Mast Cells, and Glia: Dangerous Liaisons

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    The perspective of neuroinflammation as an epiphenomenon following neuron damage is being replaced by the awareness of glia and their importance in neural functions and disorders. Systemic inflammation generates signals that communicate with the brain and leads to changes in metabolism and behavior, with microglia assuming a pro-inflammatory phenotype. Identification of potential peripheral-to-central cellular links is thus a critical step in designing effective therapeutics. Mast cells may fulfill such a role. These resident immune cells are found close to and within peripheral nerves and in brain parenchyma/meninges, where they exercise a key role in orchestrating the inflammatory process from initiation through chronic activation. Mast cells and glia engage in crosstalk that contributes to accelerate disease progression; such interactions become exaggerated with aging and increased cell sensitivity to stress. Emerging evidence for oligodendrocytes, independent of myelin and support of axonal integrity, points to their having strong immune functions, innate immune receptor expression, and production/response to chemokines and cytokines that modulate immune responses in the central nervous system while engaging in crosstalk with microglia and astrocytes. In this review, we summarize the findings related to our understanding of the biology and cellular signaling mechanisms of neuroinflammation, with emphasis on mast cell-glia interactions
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