Liderazgo distribuido y capacidad de mejora en centros de educación secundaria

El artículo que presentamos es una aproximación al estudio de las formas de liderazgo de los Institutos de Educación Secundaria. En concreto, busca verificar la presencia de formas de liderazgo distribuido en una muestra de 24 institutos de la provincia de Granada. Aplicando una metodología mixta en la que se combinan guiones de auto-observación y entrevistas semiestructuradas, se llega a concluir que el modelo de liderazgo vigente en la muestra de institutos analizados es un modelo de liderazgo burocrático apoyado en la figura de un director que actúa de manera solitaria. Aunque la muestra utilizada para la estudio es limitada, el artículo promueve una reflexión sobre la necesidad de definir la fi gura del director como elemento clave para dinamizar la capacidad de mejora de los centros de educación secundaria. The article we submit is an approach to the study of leadership on secondary schools and seeks to verify the presence or absence of distributed leadership arranged in a sample of 24 secondary schools in the Granada province. Applying a mixed methodology in which self-analysis outlines and semi-structured interviews are combined, it comes to the conclusion that the actual leadership model in the analysed secondary schools sample is a bureaucratic one supported by the figure of a director acting on his/her own. Although the sample used for the study is limited, the article encourages the reflection on the need to define the director figure as a key element in order to stimulate secondary schools'' improvement capacity

Şeref madalyası

Taha Toros Arşivi, Dosya No: 34-Safiye-Hüseyin ElbiUnutma İstanbul projesi İstanbul Kalkınma Ajansı'nın 2016 yılı "Yenilikçi ve Yaratıcı İstanbul Mali Destek Programı" kapsamında desteklenmiştir. Proje No: TR10/16/YNY/010

Evaluación de la seguridad de los anticoagulantes orales de acción directa

Objetivo: Comparar la incidencia de hemorragias entre los anticoagulantes orales (ACO) y analizar los factores que influyen en la aparición de hemorragias. Material y métodos: Estudio observacional, retrospectivo unicéntrico. Tras estudiar la población total en tratamiento con ACO, se analizó a los pacientes en tratamiento con un ACO del sector II de Zaragoza que acudieron al Servicio de Urgencias de Hospital Universitario Miguel Servet de julio a diciembre de 2015 por presentar algún evento. Se registraron datos demográficos, variables clínicas y características del evento hemorrágico. Como factores independientes en la aparición de hemorragias se valoró la dosis, fármacos, el sexo y la edad. Resultados: Había 9.452 pacientes en tratamiento con ACO, de los cuales 371 presentaron un evento hemorrágico (3, 9%). La frecuencia por ACO fue 4, 1% (311) en pacientes tratados con antagonistas de la vitamina K (AVK), 3, 8% (33) con rivaroxaban, 3, 3% (19) con dabigatran y, por último, con apixaban 2, 1% (8) (p < 0, 05). En el análisis multivariante solo obtuvieron una influencia estadísticamente significativa la selección del anticoagulante y el sexo, en concreto, la dosis de apixaban 2, 5 mg y ser mujer presentaban menor riesgo de hemorragia (OR = 0, 1; IC = 0, 014-0, 71 y OR = 0, 688; IC = 0, 55-0, 85, respectivamente). Conclusión: Según los datos obtenidos, las mujeres y los pacientes en tratamiento con apixaban presentaban menor riesgo hemorrágico, si bien existen dudas de si este mejor perfil de seguridad está relacionado con una infradosificación, que podría influir en su efectividad. Por lo tanto, estos resultados deben ser analizados con prudencia y se deben realizar más estudios para confirmar estos datos. Objective: To compare the occurrence of haemorrhages among the different oral anticoagulants (OAC) and to analyse factors that influence it. Material and methods: Single-centre, observational, retrospective study. After studying the total population treated with OAC, patients who were treated with an OAC from July 2015 to December 2015 in the II Sector of the Zaragoza Hospital, who consulted the Emergency Department of the Miguel Servet University Hospital and presented a haemorrhagic event, were analysed. Patients’ demographic data, clinical variables and data on the haemorrhagic event characteristics were gathered. Results: There were 9, 452 patients treated with an OAC, 371 (3.9%) of which presented a haemorrhagic event. The frequency per OAC was; 4.1% (311) in patients treated with vitamin K antagonists, 3.8% (33) with rivaroxaban, 3.3% (19) with dabigatran and 2.1% (8) with apixaban. In the multivariate analysis, only the choice of anticoagulant and sex had a statistically significant influence of a lower risk of haemorrhage, in particular the dose of apixaban at 2.5 mg and being female. (OR = 0.1, CI = 0.014-0.71 and OR = 0.688, CI = 0.55-0.85, respectively). Conclusion: According to the results obtained, females and patients undergoing treatment with apixaban presented lower haemorrhagic risk, although there are doubts about whether this better safety profile is related to underdosing, which could influence its effectiveness. Therefore, these results should be analysed with caution and further studies are needed to confirm this data

Possible contribution of paraquat to the development of Parkinson disease

La enfermedad de Parkinson (PD) es una de las enfermedades neurodegenerativas más comunes relacionadas con la edad que afecta a millones de personas en todo el mundo. Existen pruebas sólidas que apoyan el papel de los radicales libres, estrés oxidativo, disfunción mitocondrial y agregación de proteínas en el mecanismo de acción tóxica y muerte neuronal en la PD. Los factores ambientales, especialmente, los plaguicidas constituyen uno de los principales grupos de agentes neurotóxicos asociados a la PD. La toxicidad de los plaguicidas ha sido claramente demostrada, siendo capaces de alterar una gran variedad de funciones neurológicas. En particular, existe una fuerte evidencia que sugiere que la exposición a estas sustancias predispone a ciertas enfermedades neurodegenerativas (esclerosis lateral amiotrófica, enfermedad de Huntington, etc.). De hecho, los estudios epidemiológicos han sugerido una relación entre la exposición a determinados plaguicidas y la neurodegeneración cerebral. Cabe destacar la relación observada entre Paraquat (PQ) y la PD en estudios experimentales con roedores en los que se observan lesiones en la substancia nigra pars compacta. Sin embargo, los resultados de los estudios epidemiológicos no son definitivos en este sentido, haciéndose necesario llevar a cabo más estudios de este tipo, que estén bien diseñados para poder llegar a una conclusión firme a la hora de relacionar la exposición a PQ y la PD. En esta revisión se analizan críticamente los estudios que tratan de relacionar al PQ en el parkinsonismo, con énfasis en los mecanismos asociados con la inducción de muerte celular neuronal por esta sustancia.Parkinson's disease (PD) is one of the most common age related neurodegenerative diseases and affects millions of people worldwide. Strong evidence supports the role of free radicals, oxidative stress, mitochondrial dysfunctions and protein aggregation underlying neuronal death in PD. Environmental factors, especially pesticides represent one of the main groups of neurotoxic agents associated with PD. Pesticide toxicity has been clearly demonstrated to alter a variety of neurological functions. Particularly, there is strong evidence suggesting that pesticide exposure predisposes to neurodegenerative diseases (amyotrophic lateral sclerosis, Huntington's disease, etc.). Indeed, epidemiological data have suggested a relationship between pesticide exposure and brain neurodegeneration. Highlighting the observed relationship between paraquat (PQ) and PD in experimental studies with rodents in which lesions are seen in the substantia nigra pars compacta. However, the results of epidemiological studies are not conclusive in this regard, making it necessary to design further epidemiological studies to reach evidences in linking exposure to PQ and PD. In this paper, we analyze critically studies attempting to relate the PQ in Parkinsonism, with emphasis on the mechanisms associated with the induction of neuronal cell death by this substance

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

The elliptic, $v_2$, triangular, $v_3$, and quadrangular, $v_4$, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range $|\eta|<0.8$ at different collision centralities and as a function of transverse momentum, $p_{\rm T}$, out to $p_{\rm T}=20$ GeV/$c$. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for $p_{\rm T}>8$ GeV/$c$. The small $p_{\rm T}$ dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to $p_{\rm T}=8$ GeV/$c$. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least $p_{\rm T}=8$ GeV/$c$ indicating that the particle type dependence persists out to high $p_{\rm T}$.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186

Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}} = 2.76 TeV

The inclusive transverse momentum ($p_{\rm T}$) distributions of primary charged particles are measured in the pseudo-rapidity range $|\eta|<0.8$ as a function of event centrality in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=2.76$ TeV with ALICE at the LHC. The data are presented in the $p_{\rm T}$ range $0.15<p_{\rm T}<50$ GeV/$c$ for nine centrality intervals from 70-80% to 0-5%. The Pb-Pb spectra are presented in terms of the nuclear modification factor $R_{\rm{AA}}$ using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-$p_{\rm T}$ particles strongly depends on event centrality. In central collisions (0-5%) the yield is most suppressed with $R_{\rm{AA}}\approx0.13$ at $p_{\rm T}=6$-7 GeV/$c$. Above $p_{\rm T}=7$ GeV/$c$, there is a significant rise in the nuclear modification factor, which reaches $R_{\rm{AA}} \approx0.4$ for $p_{\rm T}>30$ GeV/$c$. In peripheral collisions (70-80%), the suppression is weaker with $R_{\rm{AA}} \approx 0.7$ almost independently of $p_{\rm T}$. The measured nuclear modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/284

Measurement of charm production at central rapidity in proton-proton collisions at s=2.76\sqrt{s} = 2.76 TeV

The $p_{\rm T}$-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D$^0$, D$^+$, and D$^{*+}$ in the rapidity range $|y|<0.5$, and for transverse momentum $1< p_{\rm T} <12$ GeV/$c$, were measured in proton-proton collisions at $\sqrt{s} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D$^0 \rightarrow$K$\pi$, D$^+ \rightarrow$K$\pi\pi$, D$^{*+} \rightarrow$D$^0\pi$, and their charge conjugates, and was performed on a $L_{\rm int} = 1.1$ nb$^{-1}$ event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at $\sqrt{s} = 2.76$ TeV and at 7 TeV was evaluated by extrapolating to the full phase space the $p_{\rm T}$-differential production cross sections at $\sqrt{s} = 2.76$ TeV and our previous measurements at $\sqrt{s} = 7$ TeV. The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/307

Two-pion Bose-Einstein correlations in central Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV at the Large Hadron Collider is presented. We observe a growing trend with energy now not only for the longitudinal and the outward but also for the sideward pion source radius. The pion homogeneity volume and the decoupling time are significantly larger than those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/388

Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV

Inclusive transverse momentum spectra of primary charged particles in Pb-Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV have been measured by the ALICE Collaboration at the LHC. The data are presented for central and peripheral collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross section. The measured charged particle spectra in $|\eta|<0.8$ and $0.3 < p_T < 20$ GeV/$c$ are compared to the expectation in pp collisions at the same $\sqrt{s_{\rm NN}}$, scaled by the number of underlying nucleon-nucleon collisions. The comparison is expressed in terms of the nuclear modification factor $R_{\rm AA}$. The result indicates only weak medium effects ($R_{\rm AA} \approx$ 0.7) in peripheral collisions. In central collisions, $R_{\rm AA}$ reaches a minimum of about 0.14 at $p_{\rm T}=6$-7GeV/$c$ and increases significantly at larger $p_{\rm T}$. The measured suppression of high-$p_{\rm T}$ particles is stronger than that observed at lower collision energies, indicating that a very dense medium is formed in central Pb-Pb collisions at the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98

Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

The yield of charged particles associated with high-$p_{\rm T}$ trigger particles ($8 < p_{\rm T} < 15$ GeV/$c$) is measured with the ALICE detector in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV relative to proton-proton collisions at the same energy. The conditional per-trigger yields are extracted from the narrow jet-like correlation peaks in azimuthal di-hadron correlations. In the 5% most central collisions, we observe that the yield of associated charged particles with transverse momenta $p_{\rm T}> 3$ GeV/$c$ on the away-side drops to about 60% of that observed in pp collisions, while on the near-side a moderate enhancement of 20-30% is found.Comment: 15 pages, 2 captioned figures, 1 table, authors from page 10, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/350