3,115 research outputs found

    Lepto-hadronic model for the broadband emission of Cygnus X-1

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    Cygnus X-1 is a well observed microquasar. Broadband observations at all wavelengths have been collected over the years. The origin of the MeV tail observed with COMPTEL and INTEGRAL is still under debate and it has mostly been attributed to the corona, although its high degree of polarization suggests it is synchrotron radiation from a jet. The origin of the transient emission above 100\sim 100 GeV is also unclear. We aim to disentangle the origin of the broadband spectral energy distribution (SED) of Cygnus X-1, focusing particularly on the gamma-ray emission, and to gain information on the physical conditions inside the jets. We develop and apply a lepto-hadronic, inhomogeneous jet model to the non-thermal SED of Cygnus X-1. We calculate the contributions to the SED of both protons and electrons accelerated in an extended region of the jet. We also estimate the radiation of charged secondaries produced in hadronic interactions, through several radiative processes. Absorption effects are considered. We produce synthetic maps of the jets at radio wavelengths. We find two sets of model parameters that lead to good fits of the SED. One of the models fits all the observations, including the MeV tail. This model also predicts hadronic gamma-ray emission slightly below the current upper limits. The flux predicted at 8.4 GHz is in agreement with the observations available in the literature, although the synthetic source is more compact than the imaged radio jet. Our results show that the MeV emission in Cygnus X-1 may be jet synchrotron radiation. This depends mainly on the strength of the jet magnetic field and the location of the injection region of the relativistic particles. Our calculations show that there must be energetic electrons in the jets quite far from the black hole.Comment: Accepted for publication in A&

    Analyzing the United States’ Limited Response to the Syrian Refugee Crisis

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    The Syrian refugee crisis can be described as one of the biggest, if not largest, humanitarian crisis of the 21st century. The crisis is a result of an ongoing civil war between rebel groups and the government forces of the Assad regime. Since the beginning of the war in 2011, over 400,000 have been killed and a combined 11 million have been displaced either internally or externally from their homes (Human Rights Watch, World Report 2018). The United Nations and the international community have openly expressed discontent with the dealings of the Assad regime, and as a result, have attempted to aid this struggling nation ridden with extreme violence. With more than 11 million displaced Syrians seeking refuge in other nation states across the world, various states have provided more lenient measures and policies to offer legal refugee resettlement within their respective borders (Morico 2017). However, the response has differed greatly on a state by state basis, with the United States resettling an inadequate number of Syrian refugees. According to the State Department, near the end of President Obama’s term in 2016, the U.S. had resettled 15,479 Syrian refugees. In 2017, the country let in 3,024. Horrifyingly, the National Public Radio has stated that by April 2018, the United States had only taken in 11 Syrian refugees (Amos 2018). These numbers are close to nothing in the grand scheme of over 11 million refugees displaced worldwide. Meanwhile nation states, such as Germany, Canada, and neighboring states of Turkey, Lebanon, and Jordan, have implemented liberal refugee policies to alleviate the crisis, despite the hardships that resettling thousands, or millions, of refugees would bring to the state. The American response to the severity of the crisis has accomplished little to alleviate the growing issue. Our response is troubling, thus sparking the question why our response to this injustice has been so limited in scope, while other world powers have accepted thousands or millions within their borders. This has created an unnecessarily hard burden on the neighboring countries around Syria, which have struggled to relocate and provide for millions of displaced refugees within their often fragile borders. These nations, including Jordan, Lebanon, and Turkey, do not have the resources and adequate social structures to provide aid for millions, as the United States and other superpowers could do more readily. Furthermore, states and international organizations have responded to the crisis by providing millions in aid and support for relocation, something that the United States has not done to the same extent. Therefore, there is an apparent need to analyze why the response from the U.S. has been drastically different and to ponder potential solutions to alleviate the burden and provide the proper support needed to help Syrians, but to also assist in lifting the burden from other struggling countries by aiding Syrian refugee resettlement. As a world superpower, we cannot turn a blind eye to an increasingly large humanitarian crisis. So, why has the United States’ response to the Syrian refugee crisis been drastically different compared to the responses from other nations? This paper will analyze how Islamophobia, xenophobia, the current state of refugee policies in the U.S., and shifts in administrations and ideologies from liberal to conservative, have shaped our response T POLITICAL ANALYSIS · VOLUME XIX · 2019 33 to the largest humanitarian crisis of the 21st century. Furthermore, by drawing comparisons to the reactions of other nation states, this paper will discuss how conservatism has influenced our foreign policy towards Syria, and has created a political environment that is unreceptive to accepting a large influx of refugees into the country, thus leading to inaction on our part. Although a nation’s foreign policy is shaped by numerous factors, by drawing comparisons between liberal and conservative approaches from other nations, it demonstrated that conservative, nationalist views have led to insubstantial refugee resettlement efforts by the United States. Furthermore, under international law and the norm of “Responsibility to Protect”, why has the United States and others not intervened to stop the ongoing and expanding crisis? As the research explains, inadequacies in the structure of the Responsibility to Protect guidelines set out by the United Nations, as a result of support from Russia and China for the Assad regime, has blocked potential intervention efforts

    Advances in the ab initio description of nuclear three-cluster systems

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    We introduce the extension of the ab initio no-core shell model with continuum to describe three-body cluster systems. We present results for the ground state of 6He and show improvements with respect to the description obtained within the no-core shell model and the no-core shell model/resonating group methods.Comment: Proceedings of the 21st International Conference on Few-Body Problems in Physics. May 18-22, 2015. Chicago, Illinois, US

    How many-body correlations and α\alpha-clustering shape 6^6He

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    The Borromean 6^6He nucleus is an exotic system characterized by two `halo' neutrons orbiting around a compact 4^4He (or α\alpha) core, in which the binary subsystems are unbound. The simultaneous reproduction of its small binding energy and extended matter and point-proton radii has been a challenge for {\em ab initio} theoretical calculations based on traditional bound-state methods. Using soft nucleon-nucleon interactions based on chiral effective field theory potentials, we show that supplementing the model space with 4^4He+nn+nn cluster degrees of freedom largely solves this issue. We analyze the role played by the α\alpha-clustering and many-body correlations, and study the dependence of the energy spectrum on the resolution scale of the interaction.Comment: 5 pages, 4 figure

    Escola de pares

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    Postgrau en Educació Emocional i Benestar, Facultat de Pedagogia, Departament de Mètodes d’Investigació i Diagnòstic en Educació, Universitat de Barcelona, curs: 2009-2010, Tutor/Tutora: Maritxell ObiolsEl present treball consisteix en el desenvolupament d'un projecte d'educació emocionant en el marc d'una escola de pares dins l'AMPA d'un col·legi d'educació primària. El projecte té la finalitat de que els pares i mares prenguin consciència d'una manera pràctica i activa de la importància d'incloure l'educació emocional a les activitats diàries. El projecte es fonamente en un marc teòric, el disseny del programa i l'avaluació del mateix

    Diagnosis tool for seawater desalination plants

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    The main objective of this project is to create a tool capable of performing a manually configurable thermoeconomic analysis of desalination plants considering the following aspects: - Current state of desalination technology. - Updating of the economic costs of each of the components that go into operation in a desalination plant. - Obtaining graphs to help analyze plant operation. Once this tool is generated, the different graphs will be reviewed and having these graphs it is possible to perform a more exhaustive analysis of desalination processes, such as seeing how the location affects the operation of the plant, see how it affects the change in operating pressure and see how it influences the percentage of recovery to be obtained. Finally, a literature-based analysis of the current situation for the different plant configurations that can be used will also be carried out. In the same way, a review of the concentrate and the different methods of concentrate extraction that exist will be carried out.Universidad de Sevilla. Máster en Sistemas de Energía Térmic

    Essential oil components encapsulated in mesoporous silica supports: a bioactive properties evaluation and toxicological approach

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    Tesis por compendioThe present PhD thesis, entitled: "Essential oil components encapsulated in mesoporous silica supports: a bioactive properties evaluation and a toxicological approach" focuses on the study of protection and controlled release of natural bioactive agents, derived from essential oil components (EOCs), encapsulated in mesoporous silica particles (MSPs). In addition, this thesis evaluatesthe silica-based supports to reduceundesirable sensorial propertiesandfor ensuring a low-health risk. The first section of the thesis shows the effect of encapsulation of EOCs in mesoporous silica supports. This study evaluates the efficiency of free and encapsulated EOCs to reduce the viability of cancer colon cell lines. This sectionalso shows the selectivity of encapsulated EOCs against cancer linesandtheir effect onnormal (non-cancer) colon cells. Results indicate that EOCs effect can be enhanced and sustained in time when EOCs are encapsulated. Moreover, EOCs' encapsulation shows promising specificity indices, reaching to double effect on colon cancer cells above normal cells. On the other hand,the encapsulation supports and their surface functionalization allows the odour masking of high volatility EOCs. Therefore, the delivery system based on MSPs represents an excellent alternative to promote controlled EOCs release, taking advance of their bioactive properties and solving the technical disadvantages related to volatility and unpleasant odours. Finally, samples used for garlic components encapsulation were immobilised in nanofibers to provide homogeneous and easy-to-handle hybrid system for controlling delivery.The developed 'composite' has potential applications on food, pharmacology, medical or engineering fields. The second sectionof the thesis evaluates the toxicity of the mesoporous silica supports through in vitro and in vivo assessments. Cell viability allows to identify the cytotoxic impact based on the kind of silica-based support, and their features (doses range, size and surface structure changes). Furthermore, the use of Caednorhabditis elegansmodel,shows the in vivo effects afterMSPs ingestion. The toxicological study confirms that size and surface structure, are decisiveMSPs' featuresfor reducing the toxicity risks for health. In summary, the present thesis evaluates the mesoporous silica-based particles as supports for EOCs encapsulation and identifies the main MSPs' features forreducingthe health-toxicity impact. Results of this thesis show that MSPs improve the EOCs activity and help to solve technical problemsof EOCs' volatility.Moreover, these results open up a suitable and safety option for oral delivery devices.La presente tesis titulada: "Componentes de aceites esenciales encapsulados en soportes mesoporosos de sílice: una evaluación de sus propiedades bioactivas y un enfoque toxicológico" se centra enla evaluación de las propiedades funcionales y organolépticas de agentes naturales bioactivos, derivados de componentes de aceites esenciales, encapsulados en materiales mesoporosos de sílice; a la vez que evalua la toxicidad de los soportes utilizados,con el fin de proponer nuevos sistemas de liberación controlada por vía oral. La primera sección de esta tesis muestra el efecto de la encapsulación de los compuestos de aceites esenciales (EOCs, por sus siglas en inglés) en soportes mesoporosos de sílice. Por un lado, seevalúa la eficiencia de los EOCs libres y encapsulados para reducir la viabilidad en líneas celulares de cáncer de colon. Además, se evalúa la selectividad de los EOCs frente a células de colon normales (líneas no tumorales). Por otro lado, seestudia la capacidad de enmascaramiento de olor de los soportes. Los resultados obtenidos, evidencian en primer lugar, que los EOCs encapsulados mejoran su actividad frente a células de cáncer,en comparacióncon la respuesta de los compuestos sin encapsular. La encapsulación hace que el efecto de los EOCs sea sostenido en el tiempo, y muestra índices de especificidad prometedores, cuandose evalua el efecto toxico de los EOCsfrente a células de cáncer de colon y células normales. Los resultados de esta primera sección, indican que los soportes basados en partículas de sílice mesoporosa (MSPs, por sus siglas en inglés) protegen y liberan eficientemente los compuestos, sino que, a la vez que la funcionalización de la superficie de las MSPs permite enmascarar el olor de los compuestos de mayor volatilidad, y con mayores inconvenientes a nivel sensorial (p.e. compuestos derivados del ajo). Por lo tanto, el sistema de encapsulación se plantea como una excelente alternativa para (i) promover la liberación controlada de EOCs, (ii) aprovechar y mejorar el efecto de sus propiedades bioactivas en células de cáncer de colón y (iii) controlar las desventajas técnicas relacionadas con la volatilidad y limitaciones organolepticas. Por último, se ha comprobado que los soportes empleados en la encapsulación de los compuestos derivados de ajo, mantienen su funcionalidad luego der ser inmovilizados en nanofribras de nylon.Con esto, se busca desarrollar un nuevo sistema de 'composite';un material híbrido y homogéneo, fácil de manejar, que libera controladamente los compuestos encapsulados desde soportes tipo fibras (composites).Estoexpande el abanico de aplicaciones de los EOCs en laindustria alimentaria y farmacológica. La segunda sección de esta tesis, evalúa la toxicidad de los soportes de sílice mesoporosa (MSPs) mediante ensayos in vitro e in vivo. En primer lugar, la viabilidad celular permite identificar el impacto citotóxico de los MSPs sobre líneas celulares de colón. En particular, se evalúa los soportes mesoporosos de sílice, tipo MCM41, en función de (i) las dosis empleadas, (ii) la diferencia de tamaño (micro y nanopartículas) y (iii) el efecto que la funcionalización de la superficie genera en la viabilidad celular. Por otro lado, empleando el modelo Caednorhabditis elegans, yadministrando por vía oral las MSPs,se evalua la influencia de las características de laspartículas (MSPs) en función de la esperanza de vida (lifespan) y la calidad con la que viven y envejecen (healthspan) los nematodos. Los resultados de este estudio,muestran que el tamaño y la estructura de la superficie de las partículas, son parámetros determinantesal momento de diseñar soportes de bajoriesgo toxicológico. En resumen, la presente tesis ha evaluado las características de la sílice mesoporosa, micro y nanoparticulada, como soporte de encapsulación para mejorar la actividad y las aplicaciones de los compuestos de aceites esenciales, al mismo tiempoLa present tesi titulada: "Components d'olis essencials encapsulats en suports mesoporosos de sílica: una avaluació de les seves propietats bioactives i un enfocament toxicològic" se centra en estudis de protecció i alliberament controlat d'agents naturals bioactius, derivats de components d'olis essencials, encapsulats en materials mesoporosos de sílica. Els components d'olis essencials encapsulats milloren les seves propietats funcionals i redueixen els problemes sensorials per aplicacions futures, garantint, al mateix temps, la baixa toxicitat dels suports desenvolupats. La primera secció de la tesi mostra l'efecte d'encapsulació dels components d'olis essencials (EOCs, per les seves sigles en anglès) en suports mesoporosos de sílica sobre la millora de les seues propietats bioactives i el camuflament de problemes sensorials. Este estudi avalua l'eficiència dels EOCs lliures i encapsulats per a reduir la viabilitat en línies cel¿lulars de càncer còlon. A més, la selectivitat dels EOCs es va provar enfront de cèl¿lules de còlon normals (no canceroses). Els resultats han demostrat que l'efecte dels EOCs pot ser millorat i sostingut en el temps quan els EOCs estan encapsulats. Encara més, l'encapsulació dels EOCs mostra índexs d'especificitat prometedors, arribant a duplicar la toxicitat en l'efecte en les cèl¿lules de càncer de còlon amb comparacio en les cèl¿lules normals. Els resultats també mostren que els suports basats en partícules de sílice mesoporoses (MSPs, per les seves sigles en anglès) no sols protegixen i alliberen EOCs eficientment, sinó que, a més, la funcionlització en superfície de les MSPs permet emmascarar l'olor dels EOCs d'alta volatilitat, que té una aplicació limitada a causa dels seus problemes sensorials(p.e. compostos derivats de l'all). Per tant, el sistema de subministrament proposat resulta una excel¿lent alternativa per a (i) promoure l'alliberament controlat de EOCs, (ii) avançant en les seues propietats bioactives en cel¿lulas de càncer còlon i (iii) controlant els desavantatges tècnics relacionats amb la volatilitat i la disseminació desagradable de les olors. Finalmet, les mostres utilitzades per encapsulació de compostos d'all es van immobilitzar en nanofibres per a proporcionar un sistema híbrid homogeni i fàcil de manejar amb administració controlada i característiques bioactives, per aplicacions potencials en l'àrea d'alimentació, farmacologia, medicina o enginyeria. La segona secció avalua la toxicitat del suports de sílice mesoporosa per mitjà d'avaluacions in vitro e in vivo. La viabilitat cel¿lular permet identificar l'impacte citotòxic basat en el tipus de suport base de sílice i les seues característiques (rang de dosi, grandària i canvis en l'estructura superficial).A més, utilitzant el model in vivo Caednorhabditis elegants, s'ha estudiat la influència de les característiques de la sílice mesoporosa, administrant micro i nanopartícules de base sílice, no sols en l'esperança de vida, sinó també en el comportament dels nematodes durant el seu envelliment. Aquest estudi ha demostrat que la grandària i l'estructura superficial, són decisius per a reduir el risc de toxicitat dels suports de sílice mesoporosa i obrir la possibilitat d'utilitzar estos materials en aplicacions d'ingesta oral. En resum, la present tesi ha avaluat les característiques de les partícules de sílice mesoporosa, com a suports d'encapsulació per a millorar l'activitat i les aplicacions dels EOCs, alhora que es va avaluar el seu principal risc tòxicologic. En conseqüència, els resultats obrin una opció adequada i de seguretat per als dispositius d'administració oral.Acosta Romero, C. (2017). Essential oil components encapsulated in mesoporous silica supports: a bioactive properties evaluation and toxicological approach [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90653TESISCompendi

    Unified ab initio approaches to nuclear structure and reactions

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    The description of nuclei starting from the constituent nucleons and the realistic interactions among them has been a long-standing goal in nuclear physics. In addition to the complex nature of the nuclear forces, with two-, three- and possibly higher many-nucleon components, one faces the quantum-mechanical many-nucleon problem governed by an interplay between bound and continuum states. In recent years, significant progress has been made in ab initio nuclear structure and reaction calculations based on input from QCD-employing Hamiltonians constructed within chiral effective field theory. After a brief overview of the field, we focus on ab initio many-body approaches - built upon the No-Core Shell Model - that are capable of simultaneously describing both bound and scattering nuclear states, and present results for resonances in light nuclei, reactions important for astrophysics and fusion research. In particular, we review recent calculations of resonances in the 6^6He halo nucleus, of five- and six-nucleon scattering, and an investigation of the role of chiral three-nucleon interactions in the structure of 9^9Be. Further, we discuss applications to the 7^7Be(p,γ)8(p,\gamma)^8B radiative capture. Finally, we highlight our efforts to describe transfer reactions including the 3^3H(d,n)4(d,n)^4He fusion.Comment: Contribution to the Special Physica Scripta Edition - 40 year anniversary - Nobel Prize '75, 71 pages, 29 figure
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