Investigating the Nature of Dark Matter with Strong Gravitational Lensing

Dark matter makes up most of the mass in the Universe, and yet its particle nature remains unknown. Structure formation arguments provide a promising avenue to address this confounding mystery, as the mass and formation mechanism of the dark matter manifests in the abundance and density profiles of dark matter halos. Measurements of the halo mass function and the mass-concentration relation can therefore be cast as direct constraints on the particle nature of dark matter itself.Strong gravitational lensing by galaxies offers a unique probe of dark matter structure across cosmological distance, circumventing the use of luminous matter to trace the underlying dark matter. Observables from strong lens systems, particularly the image magnifications in quadruply-imaged quasars, probe the halo mass function directly on sub-galactic scales, below $10^8$ solar masses. In this low-mass regime, where halos become devoid of stars and gas, various dark matter models make unique predictions that lensing can constrain. In this dissertation, I present the development and implementation of a forward modeling framework that constrains any model based on dark matter theory, provided the model predicts the form of the halo mass function, and the density profile of individual halos. Using the framework I developed, my thesis presents an unprecedented constraint on the free-streaming length of dark matter that corresponds to a lower limit of $5.2 \rm{keV}$ on the mass of a thermal relic dark matter particle. In addition, I present the first constraint on the mass-concentration relation of Cold Dark Matter halos on sub-galactic scales across cosmological distance. The flexibility of the framework I developed broadens the scope of strong-lensing analyses to any structure formation model based on dark matter theory, underscoring the power of strong gravitational lensing as a probe of fundamental physics

Antitrust and the Future of Nursing: Federal Competition Policy and the Scope of Practice

TesisEn los últimos tiempos existe una tendencia mundial hacia un mayor consumo de frutas y hortalizas, motivado fundamentalmente por una creciente preocupación por una dieta más equilibrada, con menor proporción de carbohidratos, grasas y con una mayor cantidad de fibra dietética, vitaminas y minerales. Los vegetales han tenido generalmente una forma tradicional de consumo que se ha ido modificando con el surgimiento de nuevas tecnologías de procesamiento y de preservación, (Lay Ma, 1993). El yacón (Smallanthus sonchifolia) es una raíz que se domesticó en los Andes desde la época preincaica. Los centros de mayor diversidad se localizan en las zonas fronterizas de Perú con Bolivia y Ecuador. Sin embargo, su hábitat natural se extiende desde el sur de Colombia hasta el norte de Argentina (Ferro, 2006). En el caso de frutas el objetivo es entregar al mercado un producto de la mejor calidad, con el fin de ofrecer al consumidor mejor presentación, sabor, nutrientes, aceptación y que el consumidor pague por lo que se ofrece, con el fin de obtener los beneficios deseados. Los vegetales frescos deben conservarse adecuadamente hasta el momento del consumo. Las condiciones y duración del almacenamiento influyen mucho en el aspecto y valor nutritivo. Los productos vegetales al ser cosechados deben ser acondicionados a temperaturas bajas a fin de alargar su vida útil. Con el fin de evitar que durante el almacenamiento a bajas temperaturas se produzca una alteración de los alimentos se realiza una operación denominada escaldado cuyo fin principal es el de la inactivación de las enzimas responsables de la degradación. A este respecto se utiliza la peroxidasa como indicador ya que es la más termo resistente. La finalidad básica del escaldado es la inactivación enzimática, pero además se producen otros efectos deseables en el alimento: Limpieza, se quita el polvo, los gases superficiales y aparece una nueva tonalidad en el alimento; eliminación de la carga microbiana superficial; eliminación de los gases que se encuentran ocluidos en los tejidos; suavizado del material (Loannou, 2013). En el presente trabajo se estudió el efecto que tiene la temperatura de almacenamiento y el escaldado del yacón (Smallanthus sonchifolia) sobre la peroxidasa y la variación de vitamina C, con esto se realizó el estudio de estabilidad, a fin de demostrar que un producto, podría conservarse durante largos periodos de almacenamiento y así poder retener componentes nutritivos

Initial Evaluation of an Online-Based Collaborative Repository of Research to Enhance Interdisciplinary Collaboration

Sharing research data is not a new idea; the success of the Inter-University Consortium for Political and Social Science Research (ICPSR) data archive provides evidence of data sharing’s utility in the social sciences, while recent articles (Piwowar, Becich, Bilofsky & Crowley, 2008; Piwowar, Day, & Fridsma, 2007) in the biomedical literature have reiterated the importance of data sharing to the advancement of science and knowledge. The American Psychological Association’s Ethical Principles of Psychologists and Code of Conduct (APA, 2002)affirms the importance of making research data available – to the extent possible within legal and ethical boundaries – for the purposes of reanalysis by other professionals. The availability of data sets from researchers around the world in online repositories such as ICPSR and PsychData (www.zpid.de) encourages collaborative work across institutions and national boundaries. However, such large scale efforts to share data are not ideal for serving more local aims: the encouragement of intra-and interdisciplinary collaborative research withina single institution. To meet that need, this project focuses on the creation of a searchable database of existing faculty research data sets that can be accessed internally (within Pacific University) for the purposes of developing new uses of data for theses, dissertations and scholarly publications

Strong lensing constraints on primordial black holes as a dark matter candidate

Dark matter could comprise, at least in part, primordial black holes (PBH). To test this hypothesis, we present an approach to constrain the PBH mass ($M_{\rm{PBH}}$) and mass fraction ($f_{\rm{PBH}}$) from the flux ratios of quadruply imaged quasars. Our approach uses an approximate Bayesian computation (ABC) forward modeling technique to directly sample the posterior distribution of $M_{\rm{PBH}}$ and $f_{\rm{PBH}}$, while marginalizing over the subhalo mass function amplitude, spatial distribution, and the size of the lensed source. We apply our method to 11 quadruply-imaged quasars and derive a new constraint on the intermediate-mass area of PBH parameter space $10^4$M$_{\odot}<M_{\rm{PBH}}<10^6$M$_\odot$. We obtain an upper limit $f_{\mathrm{PBH}}<0.17$ (95\% C.L.). This constraint is independent of all other previously published limits.Comment: 8 pages, 7 figures, accepted to MNRA

Potent Single-Domain Antibodies that Arrest Respiratory Syncytial Virus Fusion Protein in its Prefusion State

Human respiratory syncytial virus (RSV) is the main cause of lower respiratory tract infections in young children. The RSV fusion protein (F) is highly conserved and is the only viral membrane protein that is essential for infection. The prefusion conformation of RSV F is considered the most relevant target for antiviral strategies because it is the fusion-competent form of the protein and the primary target of neutralizing activity present in human serum. Here, we describe two llama-derived single-domain antibodies (VHHs) that have potent RSV-neutralizing activity and bind selectively to prefusion RSV F with picomolar affinity. Crystal structures of these VHHs in complex with prefusion F show that they recognize a conserved cavity formed by two F protomers. In addition, the VHHs prevent RSV replication and lung infiltration of inflammatory monocytes and T cells in RSV-challenged mice. These prefusion F-specific VHHs represent promising antiviral agents against RSV