Дисертації з теми "Warmed"

This study was conducted to determine the effect of heating methods (conventional and microwave), heating temperatures, and refrigerated storage on the flavor deterioration in precooked chicken parts. Chicken breasts and legs were evaluated by chemical analyses and sensory evaluation. Data was analyzed by Fisher's least significant difference (LSD) and Duncan's test. Results of the thiobarbituric acid test (TBA) indicated that heating temperature, regardless of heating method had a significant influence on oxidative deterioration. When the legs were heated for a longer time at a lower temperature, the TBA values significantly increased indicating heightened warmed-over flavor (WOF). Two-day refrigerated storage had no measurable influence on the TBA numbers. The legs generally had a higher degree of lipid oxidation reflected by higher TBA values. Heating method and 2-day refrigerated storage did not have a significant effect on the nonheme iron content of breasts or legs. The effects of heating temperature were inconsistent for the legs and breasts which was attributed to the different initial iron content of the legs, and the release of nonheme iron during the initial processing of the legs. The nonheme iron values of the legs were greater relative to the breasts. Heating and storage in general increased the area of peak 3 in legs, but had no effect on the breasts. A significant increase in the hexanal (peak 8) content of legs occurred upon 2-day storage, but not for breasts. Peak 7 significantly decreased when the breasts were heated, stored, and reheated. This was not the case for the legs. Sensory panelists could not differentiate between heating methods or temperatures for either part.
Master of Science

Fusarium head blight (FHB) is a serious disease of wheat (Triticum aestivum) and other small grains; disease severity is affected by temperature and rainfall. This research comprised three studies: an artificially warmed experiment during 2016-2017, a morphology study and an FHB resistance screening study in 2015-2016, using approximately 250 wheat cultivars and breeding lines from programs in the eastern US. The location was the University of Kentucky Spindletop Research Farm in Lexington, KY. Higher levels of Fusarium damaged kernels and the toxin deoxynivalenol (DON) were observed in the warmed treatment compared to the control, and plant development was accelerated. In the FHB resistance screen, significant (p < 0.05) genotype differences for all traits were observed. A GWAS identified 16 SNPs associated with resistance and susceptibility, ranging from -2.14 to 4.01%. Three DON-associated SNPs reduced toxin levels by 3.2, 2.1, and 1.5 ppm. In the morphology study, negative correlations were observed among morphological and disease traits. Small effect SNPs were identified for all morphological traits, which might be useful in genomic selection; traits like spike length, spikelet number and inclination could be used in phenotyping. Response to warming indicates that existing resistance sources may be less effective in a warming climate.

This thesis is in support of the exhibition entitled Getting Warmer, on display in Slocumb Galleries at East Tennessee State University from March 19 to March 23, 2007. The exhibition represents an exploration in the medium of fibers, incorporating digitally printed photographs on fabric and quilted structures. The collage of photographic textures and the stitched lines of machine embroidery reflect the artist's interest in the formal qualities of mapmaking and topography. Conceptually, the work is concerned with the idea of material as landscape and artwork as personal geography. This thesis addresses the artistic and cultural influences, the artistic process and previous works, and the conceptual development of the work.

Models with warped extra dimensions offer a promising solution to the hierarchy problem. However, it is known that flavour changing neutral currents arise at tree level in models with warped extra dimensions, which can lead to fatally large corrections to rare processes in the standard model. Since the introduction of the warped mechanism in 1999 by Randall and Sundrum, modifications of the original AdS5 geometries have been considered, having different phenomenologies. In particular, it has been previously shown that CP-violation in the K-K mixing system can be suppressed in what is known as the soft-wall model, in which the extra dimension is effectively compactified via a background scalar dilation field. Prior to the work presented in this thesis, however, this study had been limited to a background geometry with a specific form. A detailed study of bosonic propagators in soft-wall models has been conducted as part of this research, yielding some novel results, which permit the study of particle interactions throughout an extended family of warped 5D backgrounds in a practicable way. This methodology has then been applied, via the development of numerical routines, to an investigation of K and B meson phenomenology in a range of geometries in this family. The relevant and necessary technical prerequisites are reviewed and discussed, including (but not limited to) some of the general properties of warped extra dimensions, the application of Kaluza-Klein theory in warped 5D, topics in flavour physics and quark mixing and the application of effective field theory methods in perturbative calculations of flavour observables. It is found that there is indeed a significant interplay between the structure of the extra dimension and flavour phenomenology at a scale of 1-10 TeV. Although it turns out that the previously studied construction was already quite well-optimised with regard to flavour constraints, it is demonstrated that one can do more to ameliorate these via deformations to the background geometry and modifications to the power law dependence of the fermion masses on the extra dimension.

Durant la passada d`ecada, els models de dimensions extra corbades han estat estudiats com a candidats per a completar el Model Est`andard (ME) de la f´ısica de part´ıcules. En aquesta tesi estudiarem una s`erie d’aspectes dels models amb una dimensi´o extra corbada; en particular, la possibilitat de generalitzar la ben coneguda soluci´o de Randall-Sundrum (RS), la qual es basa en la m`etrica Anti-de Sitter (AdS). Primer, discutim la construcci´o dels models de soft-wall, que s´on una modificaci ´o de RS on la brana infraroja ha sigut substitu¨ıda per una singularitat nua a la m`etrica. Donem receptes per a construir models consistents d’aquests tipus i estudiem com la longitud de la dimensi´o extra pot ser estabilitzada. Tamb´e estudiem l’espectre de les fluctuacions que apareixen en els models de soft-wall, i trobem que podem obtenir des d’un espectre continu a partir d’una certa massa fins a un espectre discret amb un espaiament variable. Discutim les possibles aplicacions dels models de soft-wall, i finalment presentem un model concret on es pot generar una jerarquia ultravioleta/infraroja prou gran sense necessitat de cap ajust fi. Despr´es, retornem a la construcci´o original amb dues branes per tal d’estudiar com la simetria electrod`ebil pot ser trencada en models amb m`etriques generalitzades quan el bos´o de Higgs es propaga a l’engr´os de la dimensi´o extra. Veiem com les cotes sobre l’escala dels modes de Kaluza-Klein (KK), que apareixen a causa dels observables electrod`ebils de precisi´o, poden ser redu¨ıdes quan el Higgs est`a localitzat a prop de la brana infraroja. Apliquem els nostres resultats a una extensi´o m´ınima del ME en 5D, i considerem la geometria AdS i una deformaci´o d’aquesta inspirada pels models de soft-wall. Trobemque la geometria deformada redueix enormement les cotes sobre l’escala de KK, fins al punt en qu`e els estats de KK es poden trobar dins del rang de l’LHC i el problema de la petita jerarquia pot ser eliminat sense requerir la introducci´o de cap simetria custodial. Finalment, estudiem la propagaci´o de tots els fermions del ME al llarg de la dimensi´o extra, la qual cosa fem servir per tractar el problema del sabor en el ME. Trobem expressions generals i expl´ıcites per als observables electrod`ebils oblics i no oblics, aix´ı com per als operadors que violen sabor i la simetria CP. Apliquem aquest resultat al model RS i al model amb geometria deformada, per la qual cosa fem un estudi estad´ıstic a partir d’un conjunt aleatori d’acoblaments de Yukawa en 5D. La comparaci´o de les prediccions amb les dades experimentals actuals mostren una millora de les cotes en el nostre model en comparaci´o amb RS.
Models of warped extra-dimensions have been studied over the last decade as candidates to complete the Standard Model (SM) of particle physics, for they provide a natural mechanism to address its hierarchy problem. In this thesis we study a number of aspects of the five-dimensional warped models, and in particular the possibility of generalizing the well-known Randall-Sundrum (RS) solution, which is based on the Anti-de Sitter metric (AdS). We first discuss on the construction of soft-wall models, which are a modification of RS where the infrared brane is substituted by a naked singularity in the metric. We provide recipes for constructing consistent models of this kind and address the issue of how the length of the extra dimension can be stabilized. We also discuss on the spectrum of fluctuations that arise in soft-wall models, finding that it can range from a continuous spectrum above a mass gap to a discrete spectrum with a variable level spacing. We discuss on the possible applications of soft-wall models, and finally present a concrete model where a large ultraviolet/infrared hierarchy can be generated without any fine-tuning. Next, we return to the original two-brane setup to study how the electroweak symmetry can be broken in warped models with generalized metrics when the Higgs boson propagates in the bulk. We show how the bounds on the Kaluza-Klein (KK) scale that arise from electroweak precision observables can be alleviated when the Higgs is localized towards the infrared brane. We apply our results to a minimal 5D extension of the SM and consider the AdS geometry and a deformation of it inspired by soft-walls. We find that the deformed geometry greatly reduces the bounds on the KK scale, to a point where the KK states can be within the range of the LHC and the little hierarchy problem can be removed without requiring the introduction of any custodial symmetry. Finally, we study the propagation of all SM fermions in the bulk of the extra dimension, which we use to address the flavor puzzle of the SM. We find general explicit expressions for oblique and non-oblique electroweak observables, as well as flavor and CP violating operators. We apply these results to the RS model and the model with deformed geometry, for which we perform a statistical analysis departing from a random set of 5D Yukawa couplings. The comparison of the predictions with the current experimental data exhibits an improvement of the bounds in our model with respect to the RS model.

It has been known for some time that warped extra dimensions offer a potential explanation of the large hierarchy that exists between the electroweak scale and the Planck scale. The majority of this work has focused on a five dimensional slice of AdS space. This thesis attempts to address the question, what possible spaces offer phenomenologically viable resolutions to this gauge hierarchy problem. In order for a space to offer a potential resolution to the hierarchy problem two conditions must be met: Firstly one should be able to demonstrate that the space can be stabilised such that a small effective electroweak scale (or large effective Planck scale) can be obtained. Secondly one must demonstrate that the space allows for a Kaluza Klein (KK) scale that is small enough such that one does not reintroduce a hierarchy in the effective theory. Here we focus on the second condition and examine the constraints, on the KK scale, coming from corrections to electroweak observables and flavour physics which arise when gauge fields propagate in an additional dimension. We study a large class of possible spaces of different geometries and dimensionalities. In five dimensions it is found that such constraints are generically large. In more than five dimensions it is found that a significant proportion of such spaces suffer from either a high density of KK modes or alternatively strongly coupled KK fields. The latter would not offer viable resolutions to the hierarchy problem. Models in which the Higgs propagates in the bulk are also studied, in the context of models with a ‘soft wall' and it is found these have significantly reduced constraints from flavour physics as well as a notion of a minimum fermion mass.

In this thesis we introduce a notion of graphs approximating actions of finitely generated groups on metric and measure spaces. We systematically investigate expansion properties of said graphs and we prove that a sequence of graphs approximating a fixed action ρ forms a family of expanders if and only if ρ is expanding in measure. This enables us to rely on a number of known results to construct numerous new families of expander (and superexpander) graphs. Proceeding in our investigation, we show that the graphs approximating an action are uniformly quasi-isometric to the level sets of the associated warped cone. The existence of such a relation between approximating graphs and warped cones has twofold advantages: on the one hand it implies that warped cones arising from actions that are expanding in measure coarsely contain families of expanders, on the other hand it provides a geometric model for the approximating graphs allowing us to study the geometry of the expander thus obtained. The rest of the work is devoted to the study of the coarse geometry of warped cones (and approximating graphs). We do so in order to prove rigidity results which allow us to prove that our construction is flexible enough to produce a number of non coarsely equivalent new families of expanders. As a by-product, we also show that some of these expanders enjoy some rather peculiar geometric properties, e.g. we can construct expanders that are coarsely simply connected.

Housing and health care are more closely related than ever before. To address this issue head-on, Ballad Health, Appalachia Service Project, and East Tennessee State University's College of Public Health created a regional partnership to research and provide a more holistic and effective approach to healthcare by meeting the housing needs of families in northeast Tennessee and southwest Virginia. Presenters will be Nicole Intagliata, Director of Programs at ASP, and Megan Quinn, Associate Professor at East Tennessee State University. (Megan is replacing Paula Masters from Ballad Health who was originally scheduled to speak.) The session will conclude with a short presentation by Nick Oliver of Hinton Rural Life Center, winner of the Best Practices Award for Home Repair Practices. He'll share about their Healthy Homes Checklist, work with their local Red Cross chapter to check for proper smoke detector installation, and partnership with health care providers to help improve conditions at homes that are linked to health concerns.

We set out on the ambitious journey to fuse inflation and string theory. We first give a somewhat extensive, yet free from the most complicated details, review of string inflation, discussing concepts as flux compactifications, moduli stabilization, the η-problem and reheating. Then, we consider two specific configurations of type II supergravity; type IIB on T6 with D3-branes and O3-planes, and type IIA on a twisted torus with D6-branes and O6-planes. In both cases, we calculate the scalar potential from the metric ansatzes, and try to uplift it to one of de-Sitter (dS) type. In the IIA-case, we also derive the scalar potential from a super- and Kähler potential, before we search for stable dS-solutions.

ETSU Elevates Housing placed third and is represented by Appalachia Service Project (ASP), ETSU College of Public Health and Ballad Health Department of Population Health. The groups will work together to launch “Healthy Homes: Tri-Cities” to provide critical home repairs for families in the Tri-Cities region in need of warmer, safer and drier housing. The majority of these repairs will be made by volunteers from the region to elevate one family at a time out of substandard housing. In an effort to select the projects with the greatest potential return on investment for the patient and stakeholders, projects may be referred by Ballad Health or ASP will select applicants with stated health concerns.

In der vorliegenden Arbeit wurden zwei Verfahren untersucht, die eine erfolgreiche Protektion vor hepatischer Ischämie/Reperfusionsschädigung versprachen: ischämische Präkonditionierung (IP) und pharmakologische Konditionierung mit Methylprednisolon (MP). Dabei wurde zunächst das Ausmaß der hepatozellulären Schädigung nach warmer Leberischämie durch Abklemmen der blutzuführenden Gefäße im Ligamentum hepatoduodenale (Pringle-Manöver) analysiert, wobei beide Behandlungsstrategien eine vergleichbar starke Gewebsprotektion erzielten. Nach 70%-iger Leberteilresektion mit Pringle-Manöver war jedoch trotz reduzierter Ischämie/Reperfusionsschädigung die Leberregeneration nach IP-Behandlung nachhaltig eingeschränkt. Im Gegensatz dazu waren die regenerativen Vorgänge nach MP-Behandlung nicht schneller, aber doch mit einer vergleichbaren Kinetik zu unbehandelten, ischämischen Kontrollen abgelaufen. Zusammenfassend gilt, daß sowohl IP- als auch MP-Behandlung die Ischämie/Reperfusionsschädigung deutlich reduzieren. Dies hat jedoch keinen positiven Einfluß auf die nachfolgende Regeneration nach Leberteilresektion mit Pringle-Manöver.
The present study analyses two strategies to protect from hepatic ischemia-reperfusion injury: ischemic preconditioning (IP) and pharmacologic administration of methylprednisolone (MP). First, the extent of hepatocellular damage after warm liver ischemia induced by cross clamping of the hepatic vessels in the hepatoduodenal ligament (Pringle manöver) was analysed demonstrating comparable tissue protection by both treatment modalities. After 70% partial hepatectomy including Pringle manöver however, the hepatocellular regerneration was markedly decreased after IP treatment, despite reduced ischemia-reperfusion injury. Moreover, MP treatment did not improve hepatic regeneration since it showed a comparable timing to untreated, ischemic controls. In conclusion, both IP and MP significantly reduced hepatic ischemia-reperfusion injury. However, no beneficial effects on hepatocellular regeneration after partial hepatectomy including pringle manöver were observed.

This thesis aimed to model agricultural outcomes that are important to Vermont dairy farms and their surrounding communities -- runoff, erosion, nitrogen and phosphorus losses, crop yields, and timeliness of farm operations -- under a set of possible future climates. The Agricultural Policy/Environmental eXtender (APEX) model was used for this work, and the models were calibrated using data from a project that measured most of these outcomes on a set of local farms. The model setup and calibration methodology is thoroughly documented and may be a useful starting point for others who are new to agricultural modeling. Applied to two farms growing continuous corn, the future climate simulations showed that increasing temperatures by 2 C, combined with raising total precipitation or changing the seasonality of precipitation, had little effect on any outcome. Intense rainfall has increased greatly in recent decades, so a combination of higher temperatures and more intense precipitation was also simulated. This led to more runoff, more soil loss, and more nutrient losses. While median values were only modestly increased, the 95%-ile and total losses over the simulation period increased by a larger amount (as much as 53%, depending on the site). Management practices that can reduce runoff and soil/nutrient loss exist, but their effectiveness when a higher fraction of losses occur in large events is not well known. Crop yields changed by <10% in all simulations, and in some cases increased slightly. Other studies have warned of decreases in yields because of high summer temperatures and droughts. The pilot simulations in this thesis probed only a limited range of climate parameter space, so running the models for a wider range of scenarios may illuminate the circumstances in which particularly harmful and beneficial outcomes occur. Finally, APEX can in principle calculate the delays to corn planting that are expected if climate change leads to wetter conditions in the spring. However, the models consistently predicted that only harvest operations will be delayed. The reasons for this are not well understood, and it may be a useful avenue for future work. The present work is limited in a number of ways. Chief among these are somewhat mediocre model performance, and the narrow range of farming systems and climate scenarios investigated. Statistics describing the performance of the calibrated models were poorer than anticipated, and satisfactory results could not be obtained for some nutrient loss pathways. Only two farms were modeled, in just four hypothetical future climates; results for other relevant farming systems and climates may be quite different. Nonetheless, it is hoped that this thesis serves as a useful illustration of the potential and limitations of utilizing the APEX model in this context, and that it lays the groundwork for a more extensive investigation of agricultural outcomes under climate change in Vermont.

In this work we introduce an analytical approach for the frequency warping transform. Criteria for the design of operators based on arbitrary warping maps are provided and an algorithm carrying out a fast computation is defined. Such operators can be used to shape the tiling of time-frequency plane in a flexible way. Moreover, they are designed to be inverted by the application of their adjoint operator. According to the proposed mathematical model, the frequency warping transform is computed by considering two additive operators: the first one represents its nonuniform Fourier transform approximation and the second one suppresses aliasing. The first operator is known to be analytically characterized and fast computable by various interpolation approaches. A factorization of the second operator is found for arbitrary shaped non-smooth warping maps. By properly truncating the operators involved in the factorization, the computation turns out to be fast without compromising accuracy.

In this work we introduce an analytical approach for the frequency warping transform. Criteria for the design of operators based on arbitrary warping maps are provided and an algorithm carrying out a fast computation is defined. Such operators can be used to shape the tiling of time-frequency plane in a flexible way. Moreover, they are designed to be inverted by the application of their adjoint operator. According to the proposed mathematical model, the frequency warping transform is computed by considering two additive operators: the first one represents its nonuniform Fourier transform approximation and the second one suppresses aliasing. The first operator is known to be analytically characterized and fast computable by various interpolation approaches. A factorization of the second operator is found for arbitrary shaped non-smooth warping maps. By properly truncating the operators involved in the factorization, the computation turns out to be fast without compromising accuracy.

John A. Warden III är en av vår tids mest inflytelserika luftmaktsteoretiker och Wardens teori är vida omskriven och ligger till grund för flertalet undersökningar. Warden redogör själv för att teorin inte skall ses som en mall utan att det snarare är generella idéer och riktlinjer. Det gör att teorin går att applicera på många olika fall men det lämnar också utrymme för tolkning. Syftet med denna uppsatts är att undersöka ifall allmängiltigheten i Wardens teori gör att teorin tolkas olika. För att besvara frågeställningarna har en kvalitativ textanalys genomförts på ett antal utvalda uppsatser skrivna av studerande vid Försvarshögskolan. Det övergripande resultatet visar att allmängiltigheten i Wardens teori inte kan anses vara något problem då de undersökta författarna tolkat Wardens teori på ett liknande sätt.

John A. Warden’s theory the enemy as a system has been influential and attributed to large scale victories, such as Operation Desert Storm. It advocates offensive use of air power by parallel attacks on the enemy’s strategic center. While doctrines of small states are dependent and influenced by the military thinking of great power nations, its capacity and necessary priorities for the use of air power may differ. This study examines Warden’s theory through two cases, the Six Day War and the Second Lebanon War. Both relied on air power executed by a small state, Israel. The result show that Warden’s theory can partly explain Israelic victory during the Six Day War, but with substantial differentiations from the theory’s advocation of attacks on the enemy strategic leadership. The findings are ambiguous and neither strengthens nor weakens the theory. The analysis of the Second Lebanon War indicates that air power was insufficient in achieving strategic victory in the war against Hezbollah, even though the execution of the air operation had significant resemblance to Warden’s theory, thus weakening the theory.

In this thesis we study several topics within the subject of extra dimensions and composite Higgs models. We first look at a scenario with a warped extra dimension known as the Randall-Sundrum (RS) model, and put all Standard Model fields in the bulk. We investigate various aspects of the model and argue that the presence of higher dimensional operators in the 5D bulk has a non-negligible effect on the electroweak precision observables, meaning that current electroweak constraints on non-custodial warped models could be weaker than previously thought. Then, using holographic techniques, we study correlations between the top partner masses and the Higgs potential in composite Higgs models. It is known that a light Higgs (~ 125 GeV) generally requires light top partners at around 700-800 GeV. However in these calculations the 5D volume is always fixed such that the 5D cutoff is around ~ MPl. The effect of lowering this 5D cutoff has been studied previously in bulk RS models as a way of reducing constraints from some flavour and electroweak precision observables, these models were dubbed "Little Randall-Sundrum models". Here we consider a similar setup in the context of holographic composite Higgs models and show that reducing the 5D cutoff leads to a lighter Higgs without a lowering of the top partner masses or an increase in fine-tuning. We find that the model is perfectly consistent with a 125 GeV Higgs and top partners above 1 TeV. This reduced 5D cutoff implies an intermediate scale between the electroweak scale and the Planck scale. Lastly we consider a similar warped model with a low 5D cutoff, except this time our goal is to study diphoton signals from Kaluza-Klein gravitons in a warped extra dimension. With a KK graviton of mass 750 GeV and spin-1 states at ~ 2:5 TeV, we show that having a low 5D cutoff increases the diphoton signal and the decay to gluons. With this model we show that we can explain the recently observed diphoton excess in terms of a Kaluza-Klein graviton from a holographic composite Higgs model, while keeping other decay channels within the relevant experimental bounds.

We measured the mean plane of the Kuiper Belt as a function of semimajor axis. For the classical Kuiper Belt as a whole (the nonresonant objects in the semimajor axis range 42-48 au), we find a mean plane of inclination i(m) = 1 degrees.8(-0 degrees.4)(+0 degrees.7) and longitude of ascending node Omega(m) = 77 degrees(+18 degrees)(-14 degrees) (in the J2000 ecliptic-equinox coordinate system), in accord with theoretical expectations of the secular effects of the known planets. With finer semimajor axis bins, we detect a statistically significant warp in the mean plane near semimajor axes 40-42 au. Linear secular theory predicts a warp near this location due to the nu(18) nodal secular resonance; however, the measured mean plane for the 40.3-42 au semimajor axis bin (just outside the nu(18)) is inclined similar to 13 degrees to the predicted plane, a nearly 3 sigma discrepancy. For the more distant Kuiper Belt objects of semimajor axes in the range 50-80 au, the expected mean plane is close to the invariable plane of the solar system, but the measured mean plane deviates greatly from this: it has inclination i(m) = 9 degrees.1(-3 degrees.8)(+6 degrees.6) and longitude of ascending node Omega(m) = 277 degrees(+18 degrees)(-44 degrees). We estimate this deviation from the expected mean plane to be statistically significant at the similar to 97%-99% confidence level. We discuss several possible explanations for this deviation, including the possibility that a relatively close-in (a less than or similar to 100 au), unseen, small planetary-mass object in the outer solar system is responsible for the warping.

Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 55-57).
Further progress towards complete nuclear disarmament hinges upon the development of technologies that can reliably verify the authenticity of nuclear weapons without revealing classified information about their design. One recently developed approach makes use of isotope-specific nuclear resonance fluorescence (NRF) measurements to verify a candidate warhead's isotopic and geometric characteristics. To conceal sensitive design information, the NRF signal from the warhead is not directly measured, but is first convolved with that of an encrypting foil containing relevant warhead isotopes in quantities unknown to inspectors. The measured NRF spectrum from the candidate warhead is then compared with that of a trusted template warhead to confirm or deny the authenticity of the candidate warhead. This work examines the information security of this protocol by evaluating the accuracy with which an inspector can estimate warhead properties from multiple NRF peaks. A mathematical model of the measured NRF spectrum is developed, and measurement spectra are simulated for a collection of simple, representative warheads. A least squares estimator for the areal density of each resonant isotope in the warhead is calculated. It is shown that for a single measurement with a 2.6 MeV bremsstrahlung beam, the areal densities of the fissile isotopes U-235 and Pu-239 are virtually always estimated with less than 100% error. By adjusting the beam endpoint energy to 2.16 MeV, the error on the plutonium estimators is shown to increase substantially. The effect of isotopic enrichment on the quality of inference is demonstrated by varying the grade of plutonium in the warhead from 6% Pu-240 to 18% Pu-240 by mass.
by Steven Jeremiah Collins.
S.M.

Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.
Includes bibliographical references (p. 50).
by Robert W. Marcato, Jr.
S.B.and M.Eng.

International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California
During the final stages of the AMRAAM Full Scale Development effort a requirement for a miniature warhead compatible instrumentation system was established. Internal missile volume was not available to house the system but volume was identified within the external wiring harness cover. The system was required to have significant data handling capability and encryption, and had to withstand a severe environment on a small power budget. Several technologies were developed at the Pacific Missile Test Center to meet this challenge including Application-Specific Integrated Circuits (ASIC), surface mount technology, and thick and thin film hybrid microcircuits. In addition the state-of-the art in transmitters and power converters was stretched. The result was an encrypted PCM telemeter with 2 watt transmitter and antenna all in the missile wiring harness cover (along with the wires!)

During the Six-day war, Israel unexpectedly defeated four enemies and emerged victorious in only six days. This study attempts to examine how this was accomplished and the extent to which Sweden, also a small state, might be able to apply the lessons learned from Israel’s use of air power. To this end, the present study’s analysis draws on the theoretical perspectives of two widely known and acknowledged air power scholars, Robert A. Pape and John A. Warden. Their respective theories ”Coercion by Denial” and ”The Enemy as a System” on the use of air power seem in important ways to be in opposition to one another. However, study findings indicate that Israel combined elements from both approaches and neither theory can alone provide sufficient guidance for a small state. Therefore, the two theoretical perspectives were found to be complementary, where drawing on certain key dimensions of each could be the most favourable for a small state such as Sweden. In particular, the results of the analysis underline the importance of achieving air superiority. This study concludes that the uniqueness of each nation’s strategic context indicates the potential need for new theoretical insights, better tailored for small states.

This study intends to contribute to the understanding of air power theory by studying the contrasting theories of John A. Warden and Robert A. Pape onto a single case. Warden advocates strategic bombing, while Pape condemns it. The theories are applied onto the Israeli air power in the Six-Day War, a war which played an important role for air power and where air power played an important role for the outcome. Both theories are among the most discussed and criticized ones, including by the other author respectively. By thoroughly examining them onto the same single case, their generalizability is evaluated in relation to each other. The empirical data consisted of six descriptive works of the war, from which each event of air sorties was analysed and matched with the theories. The air sorties of each theory were then evaluated by occurrence and effect to the wars outcome, i.e. the contribution to the Israeli victory. The results of the analysis imply that Warden’s theory have a better ability to explain the success of the Israeli Air Force than Pape’s theory, but no major conclusions of their generalizability can be drawn. None of the theories where found fully sufficient to explain the case, i.e. some parts of the theories did not occur in Six-Day War according to the study.

The potential increase in frequency and magnitude of extreme floods is currently discussed in terms of global warming and the intensification of the hydrological cycle. The profound knowledge of past natural variability of floods is of utmost importance in order to assess flood risk for the future. Since instrumental flood series cover only the last ~150 years, other approaches to reconstruct historical and pre-historical flood events are needed. Annually laminated (varved) lake sediments are meaningful natural geoarchives because they provide continuous records of environmental changes > 10000 years down to a seasonal resolution. Since lake basins additionally act as natural sediment traps, the riverine sediment supply, which is preserved as detrital event layers in the lake sediments, can be used as a proxy for extreme discharge events. Within my thesis I examined a ~ 8.50 m long sedimentary record from the pre-Alpine Lake Mondsee (Northeast European Alps), which covered the last 7000 years. This sediment record consists of calcite varves and intercalated detrital layers, which range in thickness from 0.05 to 32 mm. Detrital layer deposition was analysed by a combined method of microfacies analysis via thin sections, Scanning Electron Microscopy (SEM), μX-ray fluorescence (μXRF) scanning and magnetic susceptibility. This approach allows characterizing individual detrital event layers and assigning a corresponding input mechanism and catchment. Based on varve counting and controlled by 14C age dates, the main goals of this thesis are (i) to identify seasonal runoff processes, which lead to significant sediment supply from the catchment into the lake basin and (ii) to investigate flood frequency under changing climate boundary conditions. This thesis follows a line of different time slices, presenting an integrative approach linking instrumental and historical flood data from Lake Mondsee in order to evaluate the flood record inferred from Lake Mondsee sediments. The investigation of eleven short cores covering the last 100 years reveals the abundance of 12 detrital layers. Therein, two types of detrital layers are distinguished by grain size, geochemical composition and distribution pattern within the lake basin. Detrital layers, which are enriched in siliciclastic and dolomitic material, reveal sediment supply from the Flysch sediments and Northern Calcareous Alps into the lake basin. These layers are thicker in the northern lake basin (0.1-3.9 mm) and thinner in the southern lake basin (0.05-1.6 mm). Detrital layers, which are enriched in dolomitic components forming graded detrital layers (turbidites), indicate the provenance from the Northern Calcareous Alps. These layers are generally thicker (0.65-32 mm) and are solely recorded within the southern lake basin. In comparison with instrumental data, thicker graded layers result from local debris flow events in summer, whereas thin layers are deposited during regional flood events in spring/summer. Extreme summer floods as reported from flood layer deposition are principally caused by cyclonic activity from the Mediterranean Sea, e.g. July 1954, July 1997 and August 2002. During the last two millennia, Lake Mondsee sediments reveal two significant flood intervals with decadal-scale flood episodes, during the Dark Ages Cold Period (DACP) and the transition from the Medieval Climate Anomaly (MCA) into the Little Ice Age (LIA) suggesting a linkage of transition to climate cooling and summer flood recurrences in the Northeastern Alps. In contrast, intermediate or decreased flood episodes appeared during the MWP and the LIA. This indicates a non-straightforward relationship between temperature and flood recurrence, suggesting higher cyclonic activity during climate transition in the Northeast Alps. The 7000-year flood chronology reveals 47 debris flows and 269 floods, with increased flood activity shifting around 3500 and 1500 varve yr BP (varve yr BP = varve years before present, before present = AD 1950). This significant increase in flood activity shows a coincidence with millennial-scale climate cooling that is reported from main Alpine glacier advances and lower tree lines in the European Alps since about 3300 cal. yr BP (calibrated years before present). Despite relatively low flood occurrence prior to 1500 varve yr BP, floods at Lake Mondsee could have also influenced human life in early Neolithic lake dwellings (5750-4750 cal. yr BP). While the first lake dwellings were constructed on wetlands, the later lake dwellings were built on piles in the water suggesting an early flood risk adaptation of humans and/or a general change of the Late Neolithic Culture of lake-dwellers because of socio-economic reasons. However, a direct relationship between the final abandonment of the lake dwellings and higher flood frequencies is not evidenced.
Ein verstärktes Auftreten von Hochwassern, sowohl in ihrer Häufigkeit als auch in ihrer Frequenz, wird im Zuge der Klimaerwärmung und einer möglichen Intensivierung des hydrologischen Kreislaufs diskutiert. Die Kenntnis über die natürliche Variabilität von Hochwasserereignissen ist dabei eine grundlegende Voraussetzung, um die Hochwassergefahr für die Zukunft abschätzen zu können. Da instrumentelle Hochwasserzeitreihen meist nur die letzten 150 Jahre abbilden sind andere Methoden erforderlich, um das Auftreten von historischen und prä-historischen Hochwassern festzustellen. Jährlich laminierte (warvierte) Seesedimente sind bedeutende natürliche Archive, denn sie liefern kontinuierliche Zeitreihen > 10000 Jahre mit einer bis zur saisonalen Auflösung. Seebecken stellen natürliche Sedimentfallen dar, wobei eingetragenes Flusssediment in den Seesedimenten als eine distinkte detritische Lage aufgezeichnet wird, und daher zur Rekonstruktion von extremen Abflussereignissen genutzt werden. Im Rahmen meiner Doktorarbeit habe ich einen 8.50 m langen Sedimentkern aus dem Mondsee (Nordostalpen) untersucht, welcher die letzten 7000 Jahre abdeckt. Dieser Sedimentkern besteht aus Kalzitwarven und eingeschalteten detritischen Lagen mit einer Mächtigkeit von 0.05-32 mm. Detritische Lagen wurden mit Hilfe einer kombinierten Methode untersucht: Mikrofaziesanalyse, Rasterelektronenmikroskopie, Röntgenfluoreszenzanalyse (µXRF) und magnetische Suszeptibilität. Dieser Ansatz ermöglicht die Charakterisierung der einzelnen detritischen Lagen bezüglich der Eintragsprozesse und die Lokalisierung des Einzugsgebietes. Auf Grundlage der Warvenzählung und 14C Datierungen sind die wichtigsten Ziele dieser Arbeit: (i) die Identifizierung der Eintragsprozesse, welche zu einem Sedimenteintrag vom Einzugsgebiet bis in den See führen und (ii) die Rekonstruktion der Hochwasserfrequenz unter veränderten Klimabedingungen. Diese Arbeit zeigt eine Untersuchung auf verschiedenen Zeitscheiben, wobei instrumentelle und historische Daten genutzt werden, um die Aufzeichnung von pre-historischen Hochwasser in den Mondseesedimenten besser zu verstehen. Innerhalb der letzten 100 Jahre wurden zwölf Abflussereignisse aufgezeichnet. Zwei Typen von detritschen Lagen können anhand von Korngröße, geochemischer Zusammensetzung und des Verteilungsmusters unterschieden werden. Detritische Lagen, welche aus siliziklastischen und dolomitischen Material bestehen, zeigen eine Sedimentherkunft vom Teileinzugsgebiet des Flysch (nördliches Einzugsgebiet) und der Nördlichen Kalkalpen (südliches Teileinzugsgebiet) auf. Diese Lagen sind im Nördlichen Becken mächtiger (0.1-3.9 mm) als im südlichen Seebecken (0.05-1.6 mm). Detritische Lagen, welche nur aus dolomitischem Material bestehen und Turbititlagen aufzeigen (0.65-32 mm), weisen auf eine Herkunft aus den Nördlichen Kalkalpen hin. Im Vergleich mit instrumentellen Zeitreihen, stammen die mächtigeren Lagen von lokalen Murereignissen im Sommer und feinere Eintragslagen von regionalen Frühjahrs- und Sommerhochwassern. Extreme Sommerhochwasser am Mondsee werden hauptsächlich durch Zyklonen vom Mittelmeer ausgelöst, z.B. Juli 1954, Juli 1997 und August 2002. Die Untersuchung des langen Sedimentkerns vom Mondsee zeigt während der letzten 2000 Jahre signifikante Hochwasserintervalle mit dekadischen Hochwasserepisoden während der Völkerwanderungszeit und im Übergang vom Mittelalter in die Kleine Eiszeit. Dies weist auf eine Verknüpfung von Abkühlungsphasen und Sommerhochwassern im Nordostalpenraum hin. Während der Mittelalterlichen Wärmephase und in der Kleinen Eiszeit kam es jedoch zu einer geringeren Hochwasseraktivität. Dies zeigt einen komplexen Zusammenhang von Temperaturentwicklung und Hochwasseraktivität in den Nordostalpen, mit einer erhöhten Zyklonenaktivät in den Übergängen von wärmeren zu kälteren Phasen. Während der letzten 7000 Jahre wurden 47 Muren und 269 Hochwasser aufgezeichnet, wobei es eine signifikante Änderung mit erhöhter Häufigkeit um 3500 und 1500 Warvenjahre v. h. gab (v.h. = vor heute = AD 1950). Diese signifikante Änderung stimmt mit einem langfristigem Abkühlungstrend überein, welcher durch alpine Gletschervorstöße und das Absinken von Baumgrenzen seit etwa 3300 Warvenjahre v.h. berichtet wird. Trotz relativ geringer Hochwasseraktivität um 1500 Warvenjahre v.h., könnte das Auftreten von Hochwasser auch das Leben Menschen in Neolithischen Pfahlbausiedlungen (5750-4750 cal. yr BP) beeinflusst haben. Während die ersten Pfahlbauten noch als Feuchtbodensiedlungen am Land entstanden, wurden spätere Siedlungen eventuell als Anpassung an stark schwankenden Seewasserspiegeln auf Pfählen im Wasser gebaut und/oder zeigen eine allgemeine Veränderung der Siedlungsaktivitäten der Neolithischen Pfahlbaukultur an, aufgrund sozio-ökonomischer Veränderungen. Ein direkter Zusammenhang zwischen dem Verlassen der Pfahlbausiedlungen und einer erhöhten Hochwasseraktivität konnte jedoch nicht festgestellt werden.

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In this work we introduce the notion of Ricci-Hessian type manifolds (M, g, cp, f, A) which is closely related to the construction of almost Ricci solitons realised as a warped product. We classify certain classes of the Ricci-Hessian type manifolds and derive some implications for almost Ricci solitons and generalised m-quasi-Einstein manifolds. We consider two complementary cases: V f and Vco are linearly independent in C'(M)- module X(M); and V f = hVso for some smooth function h on M. In the first case we show that the vector field VA belongs to the Ce•"(M)-module generated by V f and Vso, while in the second case, under additional hypothesis, the manifold is, around any regular point of f, locally isometric to a warped product.
Nesta tese apresentamos a noção de variedades tipo Ricci-Hessiano f, A) que está intrinsecamente relacionada à construção de quase-sólitons de Ricci que são produtos warped. Classificamos certas classes de variedades tipo Ricci-Hessiano e dedu-zimos algumas implicações para quase-sólitons de Ricci e variedades m-quasi-Einstein generalizadas. Consideramos dois casos complementares: V f e V40 são linearmente in-dependentes no C°°(M)-módulo X(M) e V f = hVg, para alguma função suave h sobre M. No primeiro caso mostramos que o campo vetorial VA pertence ao C°°(M)-módulo gerado por V f e Vyo, enquanto que no segundo caso, sob hipóteses adicionais, a varie-dade é, em uma vizinhança de qualquer ponto regular de f, localmente isométrica a um produto warped.

On se place dans le cadre des modèles à dimension supplémentaire courbe adressant le problème de hiérachie de jauge. On considère ainsi le scenario suggéré par Randall et Sundrum sous l'hypothèse habituelle d'une symétrie de jauge custodiale étendue à l'espace total à 5 dimensions, permettant de protéger le modèle de trop larges corrections dans le secteur électrofaible, où le champ de Higgs est indépendament localisé sur ce qui est appelée la TeV-brane. Après avoir revu les bases de théorie des champs en dimensions supplémentaires, on introduit le cadre théorique des modèles RS, nous exposons en détail la construction de notre modèle phénoménologique, ainsi que les effets engendrés par la brisure de symétrie électrofaible sur notre modèle. Nous déterminons ensuite les diverses représentations minimales des multiplets de quarks sous la symétrie custodiale permettant de résoudre l'anomalie sur l'asymétrie avant-arrière du quark bottom. Il est ensuite montré en detail qu'il existe de fortes corrections à la valeur moyenne dans le vide du Higgs induites par de forts mélanges des bosons de jauge Z et W avec leurs exitations de KK. Le lien avec les tests de précision électrofaible est développé. Nous trouvons ainsi de substancielles corrections dûes à RS aux divers couplages au Higgs, pouvant affecter sa phénoménologie. La fin de cette thèse est dédiée aux extensions SupersSymétriques des modèles à dimension supplémenaire courbe, le champ de Higgs étant toujours confiné sur la TeV-brane
Ln the framework of warped extra dimension models addressing the gauge hierarchy problem, we consider the Randall-Sundrum scenario under the usual hypothesis of a bulk custodial symmetry protecting the model from large ElectroWeak corrections together with a Higgs field localized on the so-called TeV-brane. After reviewing the basics of field theory in extra dimensions, we introduce the RS framework, and show in details the construction of our phenomenological model as well as the effects of EW symmetry breaking. We determine the several minimal quark representations allowing to address the anomalies in the forward-backward b-quark asymmetry. It is then shown in details that there can exist large corrections to the Higgs boson Vacuum Expectation Value induced by mixings of the gauge bosons with their KK excitations. The connection with EW precision tests is developed. We find possibly substantial RS corrections to the various Higgs couplings able to affect its phenomenology. The end of this thesis is dedicated to SuperSymmetric extension of warped models, the Higgs field still being confined on the TeV-brane

Warming climate and increased fire activity are expected to lead to decreased capacity of woody plant-dominated ecosystems to recover following fire (i.e., the erosion of resilience) in ecosystems globally. Systems characterized by stand-replacing fire regimes and dominated by serotinous plants (plants that release seeds from cones when heated by fire) may be particularly at risk. Two key conditions for resilience to fire in systems dominated by serotinous species are the sufficient production of cones following one fire and prior to the occurrence of subsequent stand-replacing fire (reburn) and climate conditions suitable for recruitment in the first post-fire year. Expected increases in fire frequency, hot and dry conditions during the inter-fire period, and occurrence of post-fire drought may lead to significant decreases in serotinous plant population persistence (interval squeeze). While the interval squeeze has been demonstrated for some serotinous species (e.g., Banksia spp. in Western Australia), key knowledge gaps exist regarding these resilience mechanisms in North American forests and how populations may respond in a warmer future with more fire. My thesis used closed-cone pine (Pinus attenuata and P. muricata) forests of California, USA as a study system to empirically test for evidence of the interval squeeze. Specifically, I assessed the developmental trajectories of fuels and cones over a chronosequence of three decades since stand-replacing fire to understand how reburn and population self-replacement potential develop over time. Building on these trajectories, I assessed the effects of fire interval and post-fire climate on in situ post-fire recruitment within the first two years post-fire, using a plot network of stands that burned in 2018, on intervals from 6 - 31 years. Further, for these sample fires, I used remotely sensed burn severity data to understand how time since fire and prior burn severity affected reburn probability. I found that 1) fuel development occurs rapidly in these forests, with fuels available to support a high severity reburn by ~10 years post-fire 2) canopy seedbank development to support stand self-replacement occurs by ~15 years post-fire, 3) in situ post-fire recruitment was present following all fire intervals, and reaches stand self-replacement for fire intervals ≥15 years on average, but under harsh post-fire climate conditions, fire intervals must be ≥20 years to reach stand self-replacement. Collectively, these results suggest that closed-cone pine forests are resilient to relatively frequent stand-replacing fires and warming that has occurred in the early 21st century. However, if fire recurs on an interval of <15 years, or post-fire growing seasons co-occur with severe drought conditions, resilience may be eroded. Combined with a review of the literature on the environmental conditions that have given rise to serotiny as a trait and variability in trait expression, this work provides a framework for understanding how coniferous forests dominated by serotinous species may respond to future climate and changing fire activity in ecosystems across North America, with significant implications for forest and fire management in rapidly changing environmental conditions.

Aquesta tesi s'ha desenvolupat en el marc d'un projecte europeu anomenat CLIMOOR; en aquest projecte s'ha utilitzat una nova aproximació metodològica per perllongar el període de sequera i augmentar la temperatura en ecosistemes arbustius. El CLIMOOR s'ha dut a terme en 4 països europeus (Regne Unit, Dinamarca, Holanda i Espanya) que es distribueixen al llarg d'un gradient natural en els factors climàtics que s'estudien (precipitació i temperatura). Els objectius concrets d'aquesta tesi van ser: 1) Descriure les característiques ecofisiològiques de dues espècies arbustives mediterrànies Erica multiflora i Globularia alypum, identificant els períodes d'estrès ambiental i les seves causes, 2) estudiar els efectes que podrien tenir en el futur condicions més seques o més càlides sobre l'ecofisiologia d'aquestes dues espècies mediterrànies, 3) comparar els efectes que aquests canvis climàtics podrien tenir sobre les espècies principals de 4 ecosistemes arbustius europeus. Durant els dos-tres anys d'estudi es van mesurar estacionalment diferents variables ecofisiològiques instantànies, com són el potencial hídric, l'intercanvi de gasos i la fluorescència de la clorofil·la a. També es van mesurar variables més integradores, com ara l'asimetria foliar, la concentració foliar de N y C, així com els seus isòtops estables, el creixement, la floració o la producció de biomassa aèria. Alguns dels resultats obtinguts són: (1) En les condicions climàtiques actuals, G. alypum és capaç d'aprofitar millor els períodes amb alta disponibilitat d'aigua de manera que mostra un millor rendiment fotosintètic i un més alt guany de carboni, la qual cosa es tradueix en un creixement anual major. (2) L'augment en la sequera va fer disminuir les tasses d'intercanvi de gasos d'E. multiflora i la producció de biomassa aèria en les dues espècies. També va retardar la majoria dels estadis fenològics de la floració d'aquestes dues espècies, reduint la producció de flors funcionals però augmentant la seva longevitat. (3) L'augment en la temperatura va incrementar l'eficiència fotoquímica potencial màxima en ambdues espècies, sobretot a la tardor i a l'hivern, la qual cosa indica que condicions més càlides en el futur podrien alleugerir les limitacions en el rendiment fotosintètic d'aquestes espècies degudes a les baixes temperatures. L'augment experimental en la temperatura també va incrementar la producció de biomassa aèria d'E. multiflora, però no de G. alypum. En canvi, va modificar la fenologia de la floració de G. alypum, però no d'E. multiflora. (4) Les tasses fotosintètiques van seguir el gradient latitudinal en la disponibilitat d'aigua. La reducció experimental de la precipitació va fer disminuir l'intercanvi de gasos en les espècies principals dels quatre països estudiats. No obstant això, les plantes al tractament de sequera van mostrar tasses fotosintètiques més elevades que les plantes control per a una mateixa quantitat de pluja acumulada durant els mesos anteriors a les mesures, es a dir, van mostrar una més gran eficiència fotosintètica en l'ús de l'aigua. (5) Les plantes al tractament de sequera van presentar eficiències fotoquímiques potencials més altes a migdia. (6) En general, la magnitud de la resposta a l'escalfament i a la sequera va ser diferent segons les condicions del lloc d'estudi (els llocs freds i humits, com són els del Nord d'Europa, van ser més sensibles a l'escalfament, mentre que l'ecosistema mediterrani estudiat, més càlid i més sec, va ser més sensible a la sequera), de l'estació de l'any (els processos estudiats van ser més sensibles a l'escalfament a l'hivern que a l'estiu) i de l'espècie. Les diferents respostes a la sequera i a l'augment en la temperatura de les dues espècies mediterrànies E. multiflora i G. alypum suggereix que en el futur podria haver un canvi en les seves abundàncies relatives. A més a més, els ajustos fenològics observats podrien alterar les seves interaccions amb altres organismes (per ex. polinitzadors). Tot això, podria conduir a un canvi en la composició d'espècies i en l'estructura d'aquests ecosistemes en resposta als canvis en la precipitació i en la temperatura que s'esperen per a les properes dècades.

We investigate the dynamics of the geometric transitions associated to compactified spacetimes. By including the effects of gravity we are able to follow the evolution of collapsing cycles as they attempt to undergo a topology changing transition. We perform investigations where we add a perturbation to the momentum of a static solution and observe the consequences this has on the spacetime, looking for evidence of black hole formation or collapsing cycles which could lead to singular geometry. First we look into two possible four dimensional spacelike solutions to the Einstein equations called instantons. These both have a two-sphere at the origin, these are called bolt singularities. We introduce an initial perturbation to reduce the two-sphere to a point. Rather than achieving this singular geometry we find that either a horizon forms, shielding a curvature singularity, or the cycle re-expands after an initial contraction phase. For the case where a horizon forms we identify the final state with a known analytic black-hole solution. In seven dimensions we simulate the gravitational dynamics of the conifold geometries (resolved and deformed) involved in the description of certain compact spacetimes. As the cycles of the conifold collapse towards a singular geometry we inevitably find that a horizon develops, shielding the external spacetime. The structure of the black hole is examined and we find a candidate for the final state of the collapse. In ten dimensions we investigate the time evolution due to gravitational dynamics of a spacetime which is commonly used in brane-cosmology and string compactifications called the Klebanov-Strassler geometry. Here black holes are sometimes formed but more commonly the cycles are seen to re-expand after reaching a minimum value, showing the stability of the solution against perturbations which would change its size.

The present thesis focuses on the behaviour of a particular type of Near-Unstable Cavities (NUCs), and their application to the sensitivity enhancement of current and future gravitational wave detectors. Advanced detectors use high power laser beams. A small fraction of the light energy is absorbed by the cavity mirrors and converted into heat. The operation of near-unstable cavities requires high-precision thermal control of the cavity mirrors, and thus a thermal model of the cavity mirror and its surroundings was built and is presented in this thesis. The model aids the development of mitigation strategies of thermal effects on detector sensitivity. Nearunstable cavities have been proposed as an enabling technology for future gravitational wave detectors, as their compact structure and large beam spot can reduce the thermal noise floor of the interferometer. Throughout my Ph.D., I designed and built an experiment to investigate the technical hurdles associated with near-unstable cavities. A near-unstable table-top cavity was built and accurate control achieved through length and alignment control systems. This experiment provides an insight into how far cavity parameters can be pushed towards geometrical instability. The work I carried out will aid the design of future ground-based gravitational wave detectors.