Paths to Positivity: Relational Trajectories and Interaction in Positive Stepparent-Stepchild Dyads

Stepfamilies are inherently complex family systems, marked by change, flexible boundaries, and early conflict. But the developmental pathways by which long-term stepparent relationships become positive require more study. We interviewed 38 stepchildren who had reached adulthood, to understand how their relationships with a stepparent became positive. Four relational trajectories defined these positive relationships: punctuated, consistent positive, progressive incline, and modulated turbulent. Distinctive communicative practices were associated with each trajectory, such as communicating assurances, “siding,” or revelations of character. In addition, the trajectories shared three common processes: responsiveness to stepchild vulnerability, stepparent “adding value” to the family, and maturation/ reframing of the past. Findings support the existence of multiple pathways to positivity and suggest that major fluctuations are experienced along the way. Findings are interpreted in light of existing research on stepfamily development and Afifi’s theory of resilience and relational load. Recommendations are offered for stepfamilies and professionals who serve them

Ruteo de vehículos escolares: caso de estudio de la Universidad Autónoma de Coahuila

En este trabajo se proponen un conjunto de nuevas rutas de transporte para dar servicio a la comunidad estudiantil actual del Campus Arteaga de la Universidad Autónoma de Coahuila atendiendo a la dispersidad de los estudiantes en la zona metropolitana de Saltillo. Se analiza un caso de estudio con la información de una Facultad, considerando 380 estudiantes y 46 paradas correspondientes a las colonias de Saltillo. El problema se formula matemáticamente como un modelo lineal entero mixto, el cual es resuelto a través de un optimizador comercial. Con el modelo sólo es posible resolver a optimalidad instancias de 10 paradas y 50 estudiantes, por lo que se diseñó un algoritmo heurístico constructivo híbrido basado en el algoritmo de Clarke y Wright, en donde la factibilidad de una solución se verifica al resolver una versión simplificada del modelo matemático. Se implementan dos estrategias para reducir el tiempo de cómputo del algoritmo heurístico y se reportan las nuevas rutas propuestas, así como algunas recomendaciones para facilitar la construcción de las instancias del problema

New 4-(N-cinnamoylbutyl)aminoacridines as potential multi-stage antiplasmodial leads

A novel family of 4-aminoacridine derivatives was obtained by linking this heteroaromatic core to different trans-cinnamic acids. The 4-(N-cinnamoylbutyl)aminoacridines obtained exhibited in vitro activity in the low- or sub-micromolar range against (i) hepatic stages of Plasmodium berghei, (ii) erythrocytic forms of Plasmodium falciparum, and (iii) early and mature gametocytes of Plasmodium falciparum. The most active compound, having a meta-fluorocinnamoyl group linked to the acridine core, was 20- and 120-fold more potent, respectively, against the hepatic and gametocyte stages of Plasmodium infection than the reference drug, primaquine. Moreover, no cytotoxicity towards mammalian and red blood cells at the concentrations tested was observed for any of the compounds under investigation. These novel conjugates represent promising leads for the development of new multi-target antiplasmodials.Copyright © 2023 The Authors. Published by Elsevier Masson SAS.. All rights reserved

ERCP and splenic injury

Abstractendoscopic Retrograde Colangiopancreatography (eRCP) is an invasive procedure with important complications that occurs in 5%-10% of the cases. The most frequent procedure related complications are: acute pancreatitis, hemorrhage, perforation and infection. an infrequent but potentially life threatening eRCP complication is the splenic injury, with very few cases reported in the literature. We report a patient with cholecholithiasis and biliary pancreatitis who was diagnosed with a subcapsular splenic laceration a few hours after an eRCP. Clinicians should be alerted to this potential post-procedure complication associated with eRCP

Homochirality and the need of energy

The mechanisms for explaining how a stable asymmetric chemical system can be formed from a symmetric chemical system, in the absence of any asymmetric influence other than statistical fluctuations, have been developed during the last decades, focusing on the non-linear kinetic aspects. Besides the absolute necessity of self-amplification processes, the importance of energetic aspects is often underestimated. Going down to the most fundamental aspects, the distinction between a single object -- that can be intrinsically asymmetric -- and a collection of objects -- whose racemic state is the more stable one -- must be emphasized. A system of strongly interacting objects can be described as one single object retaining its individuality and a single asymmetry; weakly or non-interacting objects keep their own individuality, and are prone to racemize towards the equilibrium state. In the presence of energy fluxes, systems can be maintained in an asymmetric non-equilibrium steady-state. Such dynamical systems can retain their asymmetry for times longer than their racemization time.Comment: 8 pages, 7 figures, submitted to Origins of Life and Evolution of Biosphere

Antigen-specific B-cell receptor sensitizes B cells to infection by influenza virus

Influenza A virus-specific B lymphocytes and the antibodies they produce protect against infection. However, the outcome of interactions between an influenza haemagglutinin-specific B cell via its receptor (BCR) and virus is unclear. Through somatic cell nuclear transfer we generated mice that harbour B cells with a BCR specific for the haemagglutinin of influenza A/WSN/33 virus (FluBI mice). Their B cells secrete an immunoglobulin gamma 2b that neutralizes infectious virus. Whereas B cells from FluBI and control mice bind equivalent amounts of virus through interaction of haemagglutinin with surface-disposed sialic acids, the A/WSN/33 virus infects only the haemagglutinin-specific B cells. Mere binding of virus is not sufficient for infection of B cells: this requires interactions of the BCR with haemagglutinin, causing both disruption of antibody secretion and FluBI B-cell death within 18 h. In mice infected with A/WSN/33, lung-resident FluBI B cells are infected by the virus, thus delaying the onset of protective antibody release into the lungs, whereas FluBI cells in the draining lymph node are not infected and proliferate. We propose that influenza targets and kills influenza-specific B cells in the lung, thus allowing the virus to gain purchase before the initiation of an effective adaptive response.National Institutes of Health (U.S.

STEM education in the twenty-first century: learning at work-an exploration of design and technology teacher perceptions and practices

Teachers’ knowledge of STEM education, their understanding, and pedagogical application of that knowledge is intrinsically linked to the subsequent effectiveness of STEM delivery within their own practice; where a teacher’s knowledge and understanding is deficient, the potential for pupil learning is ineffective and limited. Set within the context of secondary age phase education in England and Wales (11–16 years old), this paper explores how teachers working within the field of design and technology education acquire new knowledge in STEM; how understanding is developed and subsequently embedded within their practice to support the creation of a diverse STEM-literate society. The purpose being to determine mechanisms by which knowledge acquisition occurs, to reconnoitre potential implications for education and learning at work, including consideration of the role which new technologies play in the development of STEM knowledge within and across contributory STEM subject disciplines. Underpinned by an interpretivist ontology, work presented here builds upon the premise that design and technology is an interdisciplinary educational construct and not viewed as being of equal status to other STEM disciplines including maths and science. Drawing upon the philosophical field of symbolic interactionism and constructivist grounded theory, work embraces an abductive methodology where participants are encouraged to relate design and technology within the context of STEM education. Emergent findings are discussed in relation to their potential to support teachers’ educational development for the advancement of STEM literacy, and help secure design and technology’s place as a subject of value within a twenty-first Century curriculum

Developmentally Regulated Sphingolipid Degradation in Leishmania major

Leishmania parasites alternate between extracellular promastigotes in sandflies and intracellular amastigotes in mammals. These protozoans acquire sphingolipids (SLs) through de novo synthesis (to produce inositol phosphorylceramide) and salvage (to obtain sphingomyelin from the host). A single ISCL (Inositol phosphoSphingolipid phospholipase C-Like) enzyme is responsible for the degradation of both inositol phosphorylceramide (the IPC hydrolase or IPCase activity) and sphingomyelin (the SMase activity). Recent studies of a L. major ISCL-null mutant (iscl−) indicate that SL degradation is required for promastigote survival in stationary phase, especially under acidic pH. ISCL is also essential for L. major proliferation in mammals. To further understand the role of ISCL in Leishmania growth and virulence, we introduced a sole IPCase or a sole SMase into the iscl− mutant. Results showed that restoration of IPCase only complemented the acid resistance defect in iscl− promastigotes and improved their survival in macrophages, but failed to recover virulence in mice. In contrast, a sole SMase fully restored parasite infectivity in mice but was unable to reverse the promastigote defects in iscl−. These findings suggest that SL degradation in Leishmania possesses separate roles in different stages: while the IPCase activity is important for promastigote survival and acid tolerance, the SMase activity is required for amastigote proliferation in mammals. Consistent with these findings, ISCL was preferentially expressed in stationary phase promastigotes and amastigotes. Together, our results indicate that SL degradation by Leishmania is critical for parasites to establish and sustain infection in the mammalian host