Magnetohydrodynamic Simulations Of Plasma Dynamics In The Magnetospheric Cusp Region

Thesis (Ph.D.) University of Alaska Fairbanks, 2012The Earth's magnetospheric cusp regions are rich in interesting plasma physics. The geomagnetic cusps offer solar wind plasma a relatively easy entry point into the magnetosphere through magnetic reconnection with the interplanetary magnetic field. The cusp regions are characterized by various interesting and important observations such as low energy particle precipitation, significant outflow of ionospheric material, and the frequent presence of energetic particles in regions of depressed magnetic field strength. The physical mechanisms that lead to these observations is often unresolved, for instance the acceleration mechanism for energetic cusp populations is not understood, nor is it known what implications they may have on magnetospheric dynamics. It is however, well accepted that magnetic reconnection plays a critical role in the vicinity of the cusps and is likely responsible for much of the dynamics in the region. Modeling of the geomagnetic cusps is notoriously challenging. Global magnetospheric models have proven indispensable in the study of the interaction of the solar wind plasma with the Earth's magnetosphere, however, the exterior cusp region poses a significant challenge for these models due to their relatively small scale. I have developed a mesoscale cusp-like magnetic field model in order to provide a better resolution (up to 300 km) of the entire cusp region than is possible in these global models. Typical observational features of the high-altitude cusps are well reproduced by the simulation. Results for both strongly northward and strongly southward interplanetary magnetic field indicate extended regions of depressed magnetic field and strongly enhanced plasma beta (cusp diamagnetic cavities). The Alfvenic nature of the outer boundary between the cusp and magnetosheath, in addition to the flow characteristics in the region, indicate that magnetic reconnection plays an important role in structuring the high-altitude cusp region. The inner boundaries with magnetosphere are gradual transitions forming a clear funnel. These cavities further present a unique configuration in which reconnecting magnetic flux tubes may gain a significant amount of flux tube entropy (H = p1/gammaV) through topological changes due to magnetic reconnection

Preferential Land Assessment In Virginia

The post-World War II land boom has seen cities and many towns snake outward into the countryside, engulfing millions of acres of formerly open land and developing them into suburbs. Cities have expanded not merely in numbers of people; they have over the past several decades also swallowed up vast areas of heretofore rural and farm land as city dwellers have fled to the suburbs

Dos sentits de ’subjecte’ i els seus vincles

The change in the semantics of the word ‘subject’ in the epistemological-metaphysical meaning is a conceptual development which may be observed by historiographical means in various languages: it shifts from signifying a thing itself to a cognizing being which can consider things. From this development onward, some of the differentiated senses of the term ‘subject’ have ended up narrowly linked to one another. In particular, in philosophical contexts the juridical-political subject and the epistemological-metaphysical subject coalesce at the beginning of the 19th century. The conceptual developments that are correlated to this linking of meanings can be traced from medieval scholasticism and the modern political tradition, through German Enlightenment to Immanuel Kant’s works, and is finally traced to some of the consequences for the current understanding of subjectivity in contemporary thought

Common World and Wisdom in Kant’s Dreams of a Spirit-Seer, Illustrated by Dreams of Metaphysics(1766)

L’obra Somnis d’un visionari, il·lustrats mitjançant els somnis de la metafísica (1766) d’Immanuel Kant presenta un tractament juxtaposat i obertament irònic de dues temàtiques a primera vista heterogènies: la manera de fer metafísica habitual al context germànic del s. XVII i les visions sobrenaturals d’Emmanuel Swedenborg. Aquest article revisa una ambivalència interpretativa interna a l’obra, inicialment identificada per Moses Mendelssohn, que sorgeix d’aquesta juxtaposició temàtica. Segons les dues postures oposades de l’ambivalència pot classificar-se la recepció històrica de l’obra. Seguidament, es mostra la insuficiència d’algunes estratègies habituals d’interpretació del text, i se’n proposa una de nova basada en dues nocions del text, a saber, la voluntat d’assegurar un món comú i la noció de saviesa. A partir d’aquestes nocions i d’una carta que Kant escriu a Mendelssohn s’aporta una lectura del text que, finalment, se situa en referència a les dues lectures de l’ambivalència interpretativa presentada inicialment.Immanuel Kant’s Dreams of a spirit-seer elucidated by dreams of metaphysics (1766) presents a juxtaposed and openly ironic treatment of two apparently heterogenious subjects: the way of doing metaphysics common in the Seventeenth-Century German context and Emmanuel Swedenborg’s supernatural visions. This article reviews a interpretative ambivalence internal to the work originally identified by Moses Mendelssohn, which springs from its thematic juxtaposition. According to the two stances from the ambivalence one may classify the work’s historical reception. Furthermore, the insufficiency of some common strategies for interpreting the text will be shown, and a new one is proposed on the basis of two notions that appear within the text, that is, the will of ensuring a common world and the notion of wisdom. As a result of these notions and on the basis of a letter that Kant wrote to Mendelssohn, a reading of this work is proposed, which is finally situated with respect to the two readings of the interpretative ambivalence initially presented

Dos sentits de 'subjecte' i els seus vincles

[cat] El canvi semàntic del mot 'subjecte' en l'accepció epistemològica-metafísica és un desenvolupament conceptual que hom pot comprovar per via historiogràfica en diverses llengües: deixa de significar la cosa i passa a referir-se allò cognoscent que pot considerar la cosa. A partir d'aquest canvi, alguns dels sentits diferenciats del terme 'subjecte' han acabat confluint o adquirint una certa vinculació força estreta. En concret, en contextos filosòfics el subjecte jurídic-polític i el subjecte epistemològic-metafísic conflueixen a inicis del s. XIX. Els desenvolupaments conceptuals que acompanyen aquesta vinculació de sentits es tracen des de l'escolàstica medieval i la tradició política moderna, a través de la Il·lustració alemanya fins l'obra d'Immanuel Kant, i finalment a algunes de les conseqüències en la forma d'entendre la subjectivitat en el pensament contemporani.[eng] The change in the semantics of the word ‘subject’ in the epistemologicalmetaphysical meaning is a conceptual development which may be observed by historiographical means in various languages: it shifts from signifying a thing itself to a cognizing being which can consider things. From this development onward, some of the differentiated senses of the term ‘subject’ have ended up narrowly linked to one another. In particular, in philosophical contexts the juridical-political subject and the epistemological-metaphysical subject coalesce at the beginning of the 19th century. The conceptual developments that are correlated to this linking of meanings can be trace

Mapping the proteins of the herpes simplex virus type 1 capsid

The aims of the work presented in this thesis were to use a variety of mutagenesis techniques to investigate the proteins of the HSV-1 capsid. Triplexes are heterotrimers formed by two proteins in a 1:2 stoichiometry. The single-copy protein is called VP19C, and the dimeric protein is VP23. Insertional and deletional mutagenesis was carried out on VP19C and the effects of the mutations on virus growth and capsid assembly were examined. Insertional mutagenesis showed that VP19C can be divided into three regions with respect to their ability to tolerate five amino acid insertions, with two regions of approximately 100 amino acids at the N- and C-terminal regions of the protein being more tolerant of such insertions than a ~350 amino acid central region. The N-terminal ~100 amino acids of the protein, which are particularly insensitive to insertional mutagenesis, correspond to a region that is poorly conserved among herpesviruses. Some, but not all, severely disabled mutants were compromised in their ability to bind VP23 and VP5. Analysis of deletional mutants revealed the presence of an unusual nuclear localisation signal (NLS) near the N-terminus of VP19C. This was mapped to a 33 amino acid region by fusion of specific sequences to a green fluorescent protein (GFP) marker. By replacing the endogenous NLS with that from the simian virus 40 (SV40) large T antigen, we were able to show that the first 45 amino acids of VP19C were not essential for assembly of functional capsids and infectious virus particles. However, removing the first 63 amino acids resulted in the formation of aberrant capsids and prevented virus growth, suggesting that the poorly-conserved N-terminal sequences have some as-yet-unidentified function

Kant sobre el progrés de la metafísica

Treballs Finals del Màster en Pensament Contemporani i Tradició Clàssica, Facultat de Filosofia, Universitat de Barcelona. Curs: 2019-2020. Tutor: Salvi Turró i TomàsEl present treball va dirigit, per tant, a sistematitzar la forma del progrés de la metafísica segons apareix al llarg de l’obra de Kant i culmina en els Progressos de la metafísica , donant-nos l’ocasió de tractar en la seva interdependència mútua dues qüestions que sovint es treballen per separat, a saber: primer, la noció kantiana de progrés històric; segon, la comprensió kantiana de la metafísica. Pel que fa les problemàtiques relatives a una metafísica en progrés, la comesa que aquí ens ateny no consisteix ni en defensar que Kant les soluciona ni en solucionar-les nosaltres «kantianament», però sí ens atrevim a manifestar que el tractament kantià sembla internament satisfactori d’acord amb la filosofia transcendental, o bé exigit per aquesta. La conjectura sub hypotesi en la totalitat de l’estudi és que Kant s’hi troba amb aquestes problemàtiques tant en el desenvolupament del seu pensament crític com també en la seva defensa en retrospectiva. L’objectiu, dit explícitament, és fer palès com la temàtica adquireix la seva configuració i com s’articula la seva connexió amb la resta del sistema kantià previ als Progressos de la metafísica. Una resposta completa es detalla des d’una perspectiva alhora històrica i filosòfica

Background Pressure Profiles for Sonic Boom Vehicle Testing in the NASA Glenn 8- by 6-Foot Supersonic Wind Tunnel

In an effort to identify test facilities that offer sonic boom measurement capabilities, an exploratory test program was initiated using wind tunnels at NASA research centers. The subject of this report is the sonic boom pressure rail data collected in the Glenn Research Center 8- by 6-Foot Supersonic Wind Tunnel. The purpose is to summarize the lessons learned based on the test activity, specifically relating to collecting sonic boom data which has a large amount of spatial pressure variation. The wind tunnel background pressure profiles are presented as well as data which demonstrated how both wind tunnel Mach number and model support-strut position affected the wind tunnel background pressure profile. Techniques were developed to mitigate these effects and are presented

System-Level Experimental Validations for Supersonic Commercial Transport Aircraft Entering Service in the 2018-2020 Time Period

This report describes the work conducted under NASA funding for the Boeing N+2 Supersonic Experimental Validation project to experimentally validate the conceptual design of a supersonic airliner feasible for entry into service in the 2018 -to 2020 timeframe (NASA N+2 generation). The primary goal of the project was to develop a low-boom configuration optimized for minimum sonic boom signature (65 to 70 PLdB). This was a very aggressive goal that could be achieved only through integrated multidisciplinary optimization tools validated in relevant ground and, later, flight environments. The project was split into two phases. Phase I of the project covered the detailed aerodynamic design of a low boom airliner as well as the wind tunnel tests to validate that design (ref. 1). This report covers Phase II of the project, which continued the design methodology development of Phase I with a focus on the propulsion integration aspects as well as the testing involved to validate those designs. One of the major airplane configuration features of the Boeing N+2 low boom design was the overwing nacelle. The location of the nacelle allowed for a minimal effect on the boom signature, however, it added a level of difficulty to designing an inlet with acceptable performance in the overwing flow field. Using the Phase I work as the starting point, the goals of the Phase 2 project were to design and verify inlet performance while maintaining a low-boom signature. The Phase II project was successful in meeting all contract objectives. New modular nacelles were built for the larger Performance Model along with a propulsion rig with an electrically-actuated mass flow plug. Two new mounting struts were built for the smaller Boom Model, along with new nacelles. Propulsion integration testing was performed using an instrumented fan face and a mass flow plug, while boom signatures were measured using a wall-mounted pressure rail. A side study of testing in different wind tunnels was completed as a precursor to the selection of the facilities used for validation testing. As facility schedules allowed, the propulsion testing was done at the NASA Glenn Research Center (GRC) 8 x 6-Foot wind tunnel, while boom and force testing was done at the NASA Ames Research Center (ARC) 9 x 7-Foot wind tunnel. During boom testing, a live balance was used for gathering force data. This report is broken down into nine sections. The first technical section (Section 2) covers the general scope of the Phase II activities, goals, a description of the design and testing efforts, and the project plan and schedule. Section 3 covers the details of the propulsion system concepts and design evolution. A series of short tests to evaluate the suitability of different wind tunnels for boom, propulsion, and force testing was also performed under the Phase 2 effort, with the results covered in Section 4. The propulsion integration testing is covered in Section 5 and the boom and force testing in Section 6. CFD comparisons and analyses are included in Section 7. Section 8 includes the conclusions and lessons learned