Catalysts for polyimide foams from aromatic isocyanates and aromatic dianhydrides

Polyimide foam products having greatly improved burn-through and flame-spread resistance are prepared by the reaction of aromatic polyisocyanates with aromatic dianhydrides in the presence of metallic salts of octoic acid. The salts, for example stannous octoate, ferric octoate and aluminum octoate, favor the formation of imide linkages at the expense of other possible reactions

Adjustable high emittance gap filler

A flexible, adjustable refractory filler is disclosed for filling gaps between ceramic tiles forming the heat shield of a space shuttle vehicle, to protect its aluminum skin during atmospheric reentry. The easily installed and replaced filler consists essentially of a strip of ceramic cloth coated, at least along both its longitudinal edges with a room temperature vulcanizable silicone rubber compound with a high emittance colored pigment. The filler may have one or more layers as the gap width requires. Preferred materials are basket weave aluminoborosilicate cloth, and a rubber compounded with silicon tetraboride as the emittance agent and finely divided borosilicate glass containing about 7.5% B2O3 as high temperature binder. The filler cloth strip or tape is cut to proper width and length, inserted into the gap, and fastened with previously applied drops of silicone rubber adhesive

Rhabdomyolysis in an HIV cohort: epidemiology, causes and outcomes.

BackgroundThe Literature on rhabdomyolysis in the HIV-positive population is sparse and limited. We aimed to explore the incidence, patient characteristics, etiologies and outcomes of rhabdomyolysis in a cohort of HIV-positive patients identified through the Johns Hopkins HIV clinical registry between June 1992 and April 2014.MethodsA retrospective analysis of 362 HIV-positive patients with non-cardiac CK elevation ≥1000 IU/L was performed. Both inpatients and outpatients were included. Incidence rate and potential etiologies for rhabdomyolysis were ascertained. The development of acute kidney injury (AKI, defined as doubling of serum creatinine), need for dialysis, and death in the setting of rhabdomyolysis were determined. Logistic regression was used to evaluate the association of peak CK level with the development of AKI.ResultsThree hundred sixty two cases of rhabdomyolysis were identified in a cohort of 7079 patients with a 38,382 person years follow-up time. The incidence rate was nine cases per 1000 person-years (95% CI: 8.5-10.5). Infection was the most common etiology followed by compression injury and drug/alcohol use. One-third of cases had multiple potential etiologies. AKI developed in 46% of cases; 20% of which required dialysis. Thirteen percent died during follow-up. After adjustment, AKI was associated with higher CK (OR 2.05 for each 1-log increase in CK [95% CI: 1.40-2.99]), infection (OR 5.48 [95% CI 2.65-11.31]) and higher HIV viral load (OR 1.22 per 1-log increase [95% CI: 1.03-1.45]).ConclusionRhabdomyolysis in the HIV-positive population has many possible causes and is frequently multifactorial. HIV-positive individuals with rhabdomyolysis have a high risk of AKI and mortality

The radio jets of SS 433 at millimetre wavelengths

Context. SS 433 is historically a well-known microquasar in the Galaxy that has been deeply studied during the four decades elapsed since its discovery. However, observations at very high radio frequencies with good angular resolution are still very scarce in the literature. The present paper tries to partially fill this gap using archival data of the source obtained with the Atacama Large Millimeter Array (ALMA). Aims. We aim to study the SS 433 jet properties at radio frequencies corresponding to millimetre wavelengths where the synchrotron emitting particles are expected to lose their energy much faster than at lower frequencies of centimetre wavelengths. Results. A resolved view of the SS 433 radio core and jets is presented. In addition to spectral index and magnetic field measurements, we are able to estimate the age of the oldest visible ejecta still radiating significantly at millimetre wavelengths. By combining our findings with those of previous authors at lower frequencies, we confirm that the energy loss of the radiating electrons is dominated by adiabatic expansion instead of synchrotron radiative losses. In addition, we find suggestive evidence for the previously proposed period of slowed expansion within the first months of the ejecta flow, needed to simultaneously match the radiative lifetime observed in the centimetre domain. Our results argue for the need for future coordinated millimetre and centimetre interferometric observations with good time sampling throughout the SS 433 precessional cycle to better understand energetic processes in stellar relativistic jets.Comment: 14 pages, 7 figures, Accepted for publication in Astronomy & Astrophysic

The Relationship between Group Class Integration, Socio-emotional Abilities and Disruptive Behaviours Peer Group Integration Factors

Introduction: School is a socializing environment where a substantial part of children’s socio-emotional development takes place. For many children, their school years are imbued with experiences of rejection by their peers and feelings that the teacher also berates them constantly. But the role that social-emotional skills and disruptive behaviours play in these experiences is not clear. Methodology: This study analyses the relationship between integration in the class group, social-emotional skills and disruptive behaviours in a sample of 149 pupils between the ages of 10 and 12 years, using an EQI test, sociometric test, and a teacher questionnaire. Data analysis has been done using statistic descriptive and inferential tests. Results: The results show that socio-empathy and self-assessment are the best predictors for reciprocity in peer group relationships. Emotional intelligence and disruptive behaviours have a mild effect on peer acceptance and rejection. But there are differences in the rejection factors depending on sex. The most rejected boys are the ones who have poorer emotional intelligence and who overvalue selection by their peers. The most rejected girls are the ones who are less open to the group and make fewer selections. These girls also seem to exhibit lower adaptability than girls more open to the group. Conclusions: In peer acceptance there are multiple factors involved that have synergic effects, creating a loop that could magnify the differences in children’s social abilities and in the construction of their peer social network throughout their development

An object-oriented approach to task tree management in the TANGOW system

This paper describes the object-oriented features of TANGOW (Task-based Adaptive learNer Guidance On the WWW), a tool for developing Internet-based courses. This system facilitates the construction of adaptive learning environments for the WWW and is able to guide the students during their learning process based on student profiles and previous actions. In the TANGOW system, the course contents is modelled in terms of objects and relationships among them. This allows the course designer to reuse the same descriptive objects in different sections of the same course, or even in completely different courses. In addition, information about the student and his/her actions when interacting with the system is also stored as dynamic objects, which are instantiated at runtime. This makes it easy to access and update student related data.This paper has been sponsored by the Spanish Interdepartmental Commission of Science and Technology (CICYT), project number TEL97-0306

Creación de cursos adaptativos en TANGOW mediante tareas, reglas y elementos multimedia

En este artículo se describe, en términos generales, el proceso de diseño de un curso adaptativo accesible a través de Internet mediante el sistema TANGOW. En este proceso de diseño se establece una clara separación entre la estructura del curso, para cuya construcción se utilizan tareas y reglas docentes, y la asociación de contenidos a esta estructura. A continuación se analizan los distintos tipos de adaptación que pueden definirse durante el diseño de un curso entre las que se incluyen la adaptación en función del perfil del estudiante, las dependencias teóricas y prácticas entre tareas y la creación de distintas versiones de un mismo fragmento de contenido. Se describen, también, distintas aproximaciones metodológicas que facilitan la labor de di-seño de cursos adaptativos. El artículo termina con algunas conclusiones y trabajo futuro.Este trabajo ha sido financiado por la Comisión Interministerial de Ciencia y Tecnología (CICYT), con los números de proyecto TEL97-0306 y TEL1999-0181

An adaptive driving course based on HTML dynamic generation

Reprinted from the Proceedings of WebNet World Conference on the WWW and Internet 1999 with permission of AACE (http://www.aace.org).This is an electronic version of the paper presented at the World Conference on the WWW and Internet (WebNet '99) held in Honolulu (United States) on 1999In this paper we describe a new approach for developing adaptive Web based courses. These courses are defined by means of teaching tasks which correspond to basic knowledge units, and rules which describe how teaching tasks are divided into subtasks. Both tasks and rules are used at execution time to guide the students during their learning process by determining the set of achievable tasks to be presented to the student at every step. Adaptivity is implemented by presenting students with different HTML pages depending on their profile, their previous actions, and the active learning strategy. The HTML pages presented to the students are generated dynamically from general information about the type of media elements associated to each task and their layout. The whole approach is exemplified by means of a course on traffic signs

Association of Tenofovir Use With Risk of Incident Heart Failure in HIV-Infected Patients.

BackgroundThe antiretroviral medication, tenofovir disoproxil fumarate (TDF), is used by most human immunodeficiency virus-infected persons in the United States despite higher risks of chronic kidney disease. Although chronic kidney disease is a strong risk factor for heart failure (HF), the association of TDF with incident HF is unclear.Methods and resultsWe identified 21 435 human immunodeficiency virus-infected patients in the United States Veterans Health Administration actively using antiretrovirals between 2002 and 2011. We excluded patients with a prior diagnosis of HF. TDF was analyzed categorically (current, past, or never use) and continuously (per year of use). Proportional hazards regression and fully adjusted marginal structural models were used to determine the association of TDF exposure with risk of incident HF after adjustment for demographic, human immunodeficiency virus-related, and cardiovascular risk factors. During follow-up, 438 incident HF events occurred. Unadjusted 5-year event rates for current, past, and never users of TDF were 0.9 (95%CI 0.7-1.1), 1.7 (1.4-2.2), and 4.5 (3.9-5.0), respectively. In fully adjusted analyses, HF risk was markedly lower in current TDF users (HR=0.68; 95%CI 0.53-0.86) compared with never users. Among current TDF users, each additional year of TDF exposure was associated with a 21% lower risk of incident HF (95%CI: 0.68-0.92). When limited to antiretroviral-naive patients, HF risk remained lower in current TDF users (HR=0.53; 95%CI 0.36-0.78) compared to never users.ConclusionsAmong a large national cohort of human immunodeficiency virus-infected patients, TDF use was strongly associated with lower risk of incident HF. These findings warrant confirmation in other populations, both with TDF and the recently approved tenofovir alafenamide fumarate