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1
Strohmann, Thomas. "Very sparse kernel models: Predicting with few examples and few features." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3239405.
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Read, Ian James. "Few moded fibre systems." Thesis, University of Kent, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282488.
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Soares, João Paulo da Conceição. "FEW phone file system." Master's thesis, FCT - UNL, 2009. http://hdl.handle.net/10362/2229.
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Trabalho apresentado no âmbito do Mestrado em Engenharia Informática, como requisito parcial para obtenção do grau de Mestre em Engenharia Informática<br>The evolution of mobile phones has made these devices more than just simple mobile communication devices. Current mobile phones include such features as built-in digital cameras, the ability to play and record multimedia contents and also the possibility of playing games.
Most of these devices have support for Java developed applications, as well as multiple wireless technologies (e.g. GSM/GPRS, UMTS, Bluetooth, and Wi-Fi).
All these features have been made possible due to technological evolution that led to the improvement of computational power, storage capacity, and communication capabilities of these devices.
This thesis presents a distributed data management system, based on optimistic replication,named FEW Phone File System. This system takes advantage of the storage capacity and wireless communication capabilities of current mobile phones, by allowing users to carry their personal data “in” their mobile phones, and to access it in any workstation, as if they were files
in the local file system.
The FEW Phone File System is based on a hybrid architecture that merges the client/server model with peer-to-peer replication, that relies on periodic reconciliation to maintain consistency
between replicas. The system’s server side runs on the mobile phone, and the client on a
workstation. The communication between the client and the server can be supported by one of multiple network technologies, allowing the FEW Phone File System to dynamically adapt to the available network connectivity.
The presented system addresses the mobile phone’s storage and power limitations by allowing multimedia contents to be adapted to the device’s specifications, thus reducing the volume of data transferred to the mobile phone, allowing for more user’s data to be stored. The FEW Phone File System also integrates mechanisms that maintain information about the existence of other copies of the stored files (e.g. WWW), avoiding the transfer of those files from the
mobile device whenever accessing those copies is advantageous. Due to the increasing number of on-line storage resources (e.g. CVS/SVN, Picasa), this approach allows for those resources
to be used by the FEW Phone File System to obtain the stored copies of the user’s files.
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Fifelski, Constance J. "A few bold women." Online full text .pdf document, available to Fuller patrons only, 2002. http://www.tren.com.
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Mujal, Torreblanca Pere. "Interacting ultracold few-boson systems." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668191.
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In this thesis, we study the physical properties of several ultracold few-boson systems depending on the interactions between their constituents. Nowadays, experimentally, it is possible to have great control with high precision over the geometry and the interactions between the particles, making them an excellent setup to test directly the principles of quantum mechanics. A very interesting point is to study the evolution of their properties with the number of particles. The theoretical study of these systems pretends to microscopically understand the current experimental results and give support to new experimental developments.
The method that will be used is the exact diagonalization of the Hamiltonian of the system. As we will see, in spite of the attempts to improve it, the method is limited by the fact that, in practice, it is only useful to study few-particle systems. The method has several advantages. First of all, one has access to both the ground and the excited states. In second place, the method is variational and converges to the exact solution as long as the Hilbert space in which we diagonalize is enlarged.
Moreover, since we have access to the states of the system, it is possible to calculate any observable quantity of interest.
First, we will study a system of spinless bosons trapped in a two-dimensional harmonic potential. The effect of the trap is to keep the system bound. It will be seen how the presence of a repulsive interaction changes the energy spectrum and other properties of the system. For instance, the density profile, which is usually measurable, and also the two-body distribution function, which is intimately related to the existence of correlations.
Afterwards, the focus will be on the particular case of having only two bosons in the system interacting through a strong repulsive force. Inspired by the one-dimensional case where the fermionization phenomenon takes place in the strongly-interacting limit, we will study whether in two dimensions there is a resembling reminiscent effect. In other words, we will analyze if there are properties of the two strongly-interacting bosons in two dimensions that are like the ones of two noninteracting fermions.
After that, we will tackle the localization phenomenon in a one-dimensional system that is caused by an external speckle potential that introduces disorder in the system. We will show that the localization is a robust phenomenon against repulsive contact interactions.
Finally, we will study the influence of the spin-orbit coupling in a system of bosons with two possible pseudospin components, associated, for instance, to two hyperfine levels, confined in a two-dimensional harmonic trap. We will present an exhaustive analysis of the combined effects of the interaction and the spin-orbit coupling in the spectrum and the properties of the system. In particular we show the existence of a crossover in the ground state of the system susceptible to be experimentally identified.<br>En aquesta tesi, estudiarem les propietats físiques de diversos sistemes de pocs bosons ultrafreds depenent de les interaccions entre els seus constituents. Avui dia, a nivell experimental, es té un gran control amb una gran precisió de la geometria i les interaccions entre les partícules, fet que fa aquest sistemes excel·lents per comprovar de forma directa els principis de la mecànica quàntica. Un punt d'interès és comprovar l'evolució de les seves propietats amb el nombre de partícules.
L'estudi teòric d'aquests sistemes pretén entendre a nivell microscòpic els resultats experimentals actuals i donar suport pels nous avenços experimentals.
El mètode que farem servir serà la diagonalització exacta del hamiltonià del sistema. Com veurem, malgrat les millores que es poden implementar, ens trobarem amb la limitació de no poder estudiar sistemes de més d'unes quantes partícules. Els avantatges d'aquest mètode són diversos. En primer lloc, podrem obtenir no només l'estat fonamental del sistema sinó que també els primers estats excitats. En segon lloc, el mètode és variacional i sabem que convergeix cap a la solució exacta a mesura que ampliem l'espai de Hilbert en que diagonalitzem. A més a més, en tenir accés als estats del sistema, podem calcular qualsevol quantitat observable que sigui d'interès.
Primerament, estudiarem un sistema de bosons sense espín atrapats en un potencial harmònic bidimensional. L'efecte de la trampa és de mantenir el sistema lligat. En haver-hi una interacció repulsiva, veurem com canvia l'espectre d'energia del sistema i també altres propietats. Per exemple, la seva densitat, que habitualment es pot mesurar, i també la funció de distribució de dos cossos, que va íntimament lligada a l'existència de correlacions.
Tot seguit, ens centrarem en el cas particular de tenir només dos bosons en el sistema interaccionant a través d'una gran força repulsiva. Inspirats pel cas unidimensional en que té lloc el fenomen de la fermionització en el limit d'interacció molt forta, estudiarem si en el cas bidimensional hi queda cap reminiscència d'aquest efecte. En altres paraules, analitzarem si hi ha propietats dels dos bosons fortament interactuants en dues dimensions que siguin com les de fermions no interactuants en el mateix sistema.
A continuació, tractarem el fenomen de la localització en un sistema unidimensional en el qual hi ha un potencial extern de tipus speckle que introdueix desordre en el sistema. Veurem que la localització és un fenomen robust en front de les interaccions repulsives.
Per últim, estudiarem la influència de l'espín-òrbita en un sistema de bosons amb dues components de pseudoespín, associades, per exemple, a dos nivells hiperfins, atrapats en un potencial harmònic bidimensional. Presentarem un anàlisi exhaustiu dels efectes conjunts de la interacció i l'espín- òrbita en l'espectre i en les propietats del sistema. En particular, mostrarem l'existència d'un encreuament en l'estat fonamental del sistema susceptible de ser identificat experimentalment.
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Sakhr, Jamal Bhaduri Rajat K. "The semiclassical few-body problem /." *McMaster only, 2003.
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Wolczuk, Dan. "Intervals with few Prime Numbers." Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/1064.
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In this thesis we discuss some of the tools used in the study of the number of primes in short intervals. In particular, we discuss a large sieve density estimate due to Gallagher and two classical delay equations. We also show how these tools have been used by Maier and Stewart and provide computational data to their result.
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Bultena, Albertha. "Venn diagrams with few intersections." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0002/MQ36611.pdf.
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Ramirez, Lourdes Patricia. "Few-cycle OPCPA laser chain." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00806245.
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The Apollon-10 PW laser chain is a large-scale project aimed at delivering 10 PW pulses to reach intensities of 10^22 W/cm^2. State of the art, high intensity lasers based solely on chirped pulse amplification (CPA) and titanium sapphire (Ti:Sa) crystals are limited to peak powers reaching 1.3 PW with 30-fs pulses as a result of gain narrowing in the amplifiers. To access the multipetawatt regime, gain narrowing can be suppressed with an alternative amplification technique called optical parametric chirped pulse amplification (OPCPA), offering a broader gain bandwidth and pulse durations as short as 10 fs. The Apollon-10 PW laser will exploit a hybrid OPCPA-Ti:Sa-CPA strategy to attain 10-PW pulses with 150 J and 15 fs. It will have two high-gain, low-energy amplification stages (10 fs ,100 mJ range) based on OPCPA in the picosecond and nanosecond timescale and afterwards, and will use Ti:Sa for power amplification to the 100-Joule level.Work in this thesis involves the progression of the development on the Apollon-10 PW front end and is focused on the development of a high contrast, ultrashort seed source supporting 10-fs pulses, stretching these pulses prior to OPCPA and the implementation of the picosecond OPCPA stage with a target of achieving 10-mJ pulses and maintaining its bandwidth. To achieve the final goal of 15-fs, 150-J pulses, the seed source must have a bandwidth supporting 10-fs and a temporal contrast of at least 10^10. Thus from an initial commercial Ti:Sa source delivering 25-fs pulses with a contrast of 10^8, spectral broadening via self-phase modulation and contrast enhancement with cross polarized (XPW) generation was performed. Subsequently, the seed pulses were stretched to a few picoseconds to match the pump for picosecond OPCPA. Strecher designs using an acousto-optic programmable dispersive filter (dazzler) for phase control in this purpose are studied. A compact and straightforward compressor using BK7 glass is used and an associated compressor for pulse monitoring was also studied. Lastly, the picosecond OPCPA stage was implemented in single and dual stage configurations.
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Cherry, Donna J., and John G. Orme. "The Vital Few Foster Mothers." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/7640.
Full textAbstract:
Many foster parents serve only briefly, and foster and adopt few children. Anecdotal reports suggest that a small percentage of foster parents provide a disproportionate amount of care; however, we know virtually nothing about these parents. This study applied the Pareto Principle, also known as the 80-20 rule or Vital Few, as a framework to conceptualize these foster parents. Using latent class analysis, two classes of mothers were identified: one accounted for 21% of mothers and the other 79%. We refer to the former as the Vital Few and the latter as the Useful Many. Vital Few mothers fostered 73% of foster children - 10 times more than Useful Many mothers although only fostering three times longer. They adopted twice as many foster children while experiencing half the yearly rate of placement disruptions. Vital Few mothers were less likely to work outside the home, had better parenting attitudes, more stable home environments, more time to foster, and more professional support for fostering, but less support from kin. Further, they were as competent as the Useful Many on numerous other psychosocial measures. Understanding characteristics of these resilient Vital Few can inform recruitment and retention efforts and offer realistic expectations of foster parents.
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Silero, Rejane Wagner Protzner. "Os quantificadores a few e few: questões de interlíngua e prosódia semântica em corpus de aprendizes." Universidade Federal de Minas Gerais, 2014. http://hdl.handle.net/1843/MGSS-9MQQ4B.
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The investigation described here was carried out under the light of what has been done by researchers (GRANGER; TRIBBLE, 1998) who are interested in learner English writing. The main goal was to verify and describe the upper-intermediate Brazilian learners interlanguage, specifically concerning the use of the quantifying expressions a few and few. Data from Br- ICLE, the Brazilian subcorpus of the International Corpus of Learner English (ICLE) was analyzed so as to enable description both on the grammatical level and on the level of semantic prosody. Similarly, data from the Louvain Corpus of Native English Essays (LOCNESS), which was built to be the native equivalent for ICLE, was analyzed and used for comparisons. It was also necessary to resort to the academic section of COCA as another reference corpus in order to describe the way native speakers use the quantifiers being studied. The data from both Br-ICLE and LOCNESS were treated qualitatively, through manual analyses of the expanded context of concordance lines whose node word was few. The following sorts of collocations were identified and compared: the collocations that appeared adequate, that is, compatible with native speakers use; and the ones that appeared inadequate, that is, showing deviations that were further systematized and discussed. The type of inadequacy that received special treatment was the one related to the surfacing of semantic prosody. In the native speakers corpus, the collocation very few was often used to express negative semantic prosody; however, this was not attested in the Br-ICLE, which leads to the understanding that such collocation was underused by the learners in similar contexts. Quantitatively, the results of this research were described in percentages, and the diagnosed underuse was validated through statistical testing. In order to gauge the extent to which the mother tongue influences the expression of semantic prosody in the target language, another corpus, whose size is on a par with Br-ICLE and LOCNESS, was compiled: the Co-RAP, which stands for Corpus of Academic Essays in Portuguese (Brazilian Portuguese). Also, the online platform of Corpus do Português was used for further necessary searches. The conclusion drawn was that, in their writing, Brazilians do not seem to widely use muito poucos(as), which is the correspondent collocation in Portuguese to very few, and this may influence their lexical choices when writing in English. Lastly, following the tenets of Data- Driven Learning (JOHNS, 1994), a classroom activity that encourages the recognition of lexico-grammatical patterns was suggested, and promising pathways to future research were mentioned as well.<br>A pesquisa aqui descrita foi conduzida à luz do que já foi realizado por pesquisadores (GRANGER; TRIBBLE, 1998) que se interessam pela produção escrita de aprendizes de inglês. O objetivo geral foi o de verificar e descrever a interlíngua dos aprendizes brasileiros de inglês em nível intermediário-avançado, especificamente quanto ao uso que eles fazem das expressões quantificadoras a few e few em suas produções escritas. Utilizando os dados do Br-ICLE, subcorpus brasileiro do International Corpus of Learner English (ICLE), foram feitas análises que permitiram vislumbrar esse uso não somente em nível gramatical como também em nível de prosódia semântica. Similarmente, foram analisados dados provenientes do corpus de nativos equivalente ao ICLE, o Louvain Corpus of Native English Essays (LOCNESS) para fins comparativos. Recorreu-se, também, ao COCA acadêmico como outro corpus de referência para a descrição do uso que os nativos fazem dos quantificadores em estudo. Os dados do Br-ICLE e do LOCNESS foram tratados qualitativamente por meio de análises manuais do contexto expandido das linhas de concordância com o nódulo few. Foram identificadas e comparadas colocações que se mostraram adequadas, em consonância com o uso dos nativos, e que se mostraram inadequadas, apresentando desvios que foram sistematizados e comentados. O tipo de inadequação que recebeu tratamento especial foi a concernente à manifestação da prosódia semântica. Foi detectado que no corpus dos nativos houve um considerável número de ocorrências da colocação very few para expressar prosódia semântica negativa, fato não verificado no Br-ICLE, atestando subuso dessa colocação pelos aprendizes. Quantitativamente, os resultados obtidos nesse trabalho foram descritos em porcentagens e o subuso identificado recebeu validação por meio de teste estatístico. A fim de averiguar a extensão da influência da língua materna no uso que os aprendizes fizeram dos quantificadores, especialmente mediante a interface com a prosódia semântica, foi compilado o Corpus de Redações Acadêmicas em Português (Co-RAP), de tamanho semelhante ao Br- ICLE e ao LOCNESS, e também foi utilizado o Corpus do Português (online) para demais consultas. A conclusão foi a de que os falantes brasileiros, em suas produções escritas, não fazem um vasto uso de muito poucos(as), que seria a colocação correspondente a very few, e isso pode interferir em suas escolhas lexicais na língua-alvo. Por fim, foi sugerida, aos moldes dos princípios da Aprendizagem Movida por Dados (JOHNS, 1994), uma atividade que estimula a identificação de padrões léxico-gramaticais para os quantificadores investigados, e também foram sugeridos caminhos para próximas pesquisas.
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Dickson, Crispin. "A few aspects of aircraft noise." Licentiate thesis, Stockholm : Teknisk akustik, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4510.
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Schwarz, Alexander. "Few-cycle phase-stable infrared OPCPA." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-171942.
Full textAbstract:
Few-cycle laser pulses are an important tool for investigating laser-matter interactions. Apart
from the mere resolution used in time-resolved processes, owing to this approach table-top
sources nowadays can reach the limits of the perturbative regime and therewith enable extreme
nonlinear optics. In the visible domain, femtosecond technology over the last decades has quickly developed, in recent years leading to the routine generation of carrier-envelope phase (CEP) stable few-cycle laser pulses at high energies, using ubiquitous Ti:Sapphire amplifiers.
Near to mid-infrared few-cycle pulses in contrast can be employed for investigating interactions
in the tunneling regime. The ponderomotive potential of the infrared light field allows quivered charged particles to acquire large energies, leading to applications like the generation of isolated attosecond pulses in the water window. In this wavelength regime however, the required sources are yet to be demonstrated or at least matured. The best candidate for few-cycle pulses in this domain is optical parametric amplification.
This work describes the development of an optical parametric chirped pulse amplifier (OPCPA),
used to create CEP-stable few-cycle pulses in the near infrared (NIR). It covers all essential parts of the system. First the signal pulses are generated from ultrashort lasers using spectral broadening techniques in chapter 2. After compression of these white light continua, intra-pulse broadband difference frequency generation yields CEP stable infrared
pulses spanning over more than one octave.
A thin-disk-based pump laser provides ample pump energy (20 mJ) at pulse durations around
1.5 ps. Its characterization and optimization for OPCPA is performed in chapter 3. The high
peak energy of this pump laser leads to the buildup of optical nonlinearities and consequently
shows distinct influence on the OPCPA system performance.
The synchronization of the OPCPA pump and seed laser system is the topic of chapter 4. This
chapter is not limited to NIR systems, but demonstrates enhanced (actively stabilized) synchronization of the jitter between pump and seed pulses to σ = 24 fs, which later results in improved output stability.
The NIR OPCPA centered at 2.1 μm is described in chapter 5. This combines the efforts of
the previous chapters and describes the generation and characterization of 100 μJ sub-two-cycle CEP-stable pulses, the shortest published to date at this energy level.
As a first prototype (cutting edge) experiment, CEP dependent sub-fs currents in a dielectric are
generated in chapter 6 using the developed light source. The results compared well to visible
few-cycle laser sources and demonstrate the usability of the OPCPA system (beyond the charac-
terizations of chapter 5) for investigating sub-cycle carrier dynamics in dielectrics.
For the same purpose, to generate the currently most broadband NIR continua at kHz repetition
rates and mJ-level pulse energies, the OPCPA system is further boosted and efficiently broadened to three optical octaves using a hollow core fiber setup (described in chapter 7). The spectral phase is characterized and demonstrates self-compression in the NIR around 1.3 μm. The process provides CEP-stable sub-2-cycle pulses in this regime directly, the shortest and most powerful reported to date.
Furthermore, the spectral broadening in the infrared shows enhanced low-order harmonic gen-
eration and cross-phase-modulation as the dominant mechanism. Experimentally the limited
influence on the driver bandwidth is investigated. It is found that the processes allow using more efficient many-cycle infrared sources to generate several-octave spanning, compressible continua in the future. Even partial compression of these would then provide NIR transients for high-field experiments.<br>Die Femtosekunden-Technologie hat sich in den letzten Jahrzehnten schnell fortentwickelt, vor
allem im sichtbaren Wellenl ̈angen-Bereich. Speziell moderne Titanium-Saphir Verst ̈arker haben
zuletzt zu (Träger-Einhüllenden-) phasenstabilen und hochenergetischen Laserpulsen geführt,
die nur noch aus einzelnen optischen Zyklen bestehen. Diese erlauben die Investigation extrem
nichtlinearer optischer Prozesse im Regime der Multiphotonenionisation. Um weiter im Infraroten Prozesse im Regime der Tunnelionisation zu untersuchen, fehlt es jedoch nach wie vor an Lichtquellen mit ähnlichen Characteristiken für Anwendungen wie die
Generation von isolierten Attosekunden-Pulsen im Wasser-Transmissions-Fenster. Hier bietet
die optische parametrische Verstärkung bisher die größten Perspektiven.
Diese Arbeit beschäftigt sich mit der Entwicklung eines optischen parametrischen Verstärkers mit gestreckten Pulsen (engl.: optical parametric chirped pulse amplifier, OPCPA), der TE-
phasen-stabile Pulse mit wenigen optischen Zyklen im nahen Infraroten erzeugt. Alle wesentlichen Teile des Systems werden beschrieben. Zuerst wird der Saat-Puls durch die spektrale Verbreiterung eines Titanium-Saphir Verstärkers gewonnen. Nach der Kompression des generierten Weißlichts führt die breitbandige Differenz-Frequenz-Generation (DFG) des Pulses
mit sich selbst zu TE-phasen-stabilen Infrarot-Pulsen, deren Spektrum mehr als eine optische
Oktave aufspannt.
Ein Scheiben-Laser liefert die Pumpenergie (20 mJ) bei einer Pulsdauer von ca. 1.5 ps. Seine
Charakterisierung und Optimierung für die OPCPA erfolgt in Kapitel 3. Die hohen Spitzeninten-
sit ̈aten dieses Pumplasers führen zum Akkumulieren optischer Nichtlinearit ̈aten und beeinflussen die OPCPA im Folgenden negativ.
Die Synchronisation von OPCPA Pump- und Saat-Lasern ist das Thema von Kapitel 4. Es demonstriert eine aktive Stabilisierung des zeitlichen Überlapps beider Pulse, der den gesamten
Prozess im Folgenden stabilisiert, und ist nicht auf den Einsatz im Infraroten beschränkt, sondern
für die meisten OPCPA Systeme anwendbar.
Die in Kapitel 5 beschriebene infrarote OPCPA hat ihre Zentralwellenlänge bei 2.1 μm und baut
auf den vorherigen Kapiteln auf. Die Erzeugung und Charakterisierung von Pulsen mit weniger
als zwei optischen Zyklen, den bisher kürzesten in diesem Wellenlängen-Bereich und einer En-
ergie von 100 μJ, werden beschrieben. Ferner erweist sich die TE-Phase der verstärkten Pulse
als außerordentlich kurz- und langzeitstabil.
Kapitel 6 demonstriert dann die Möglichkeiten des neuen Systems mit einem technisch anspruchsvollen
Experiment. TE-phasen-abhängige Ströme mit einer Lebenszeit auf der Skala von Attosekunden
werden in einem Dielektrikum erzeugt und gemessen. Die Resultate stimmen gut mit den bere-
its gemessenen Werten im sichtbaren Bereich u ̈ berein und demonstrieren die Möglichkeiten und
Einsetzbarkeit des Systems.
Für ähnliche Anwendungen, allerdings bei noch höheren Intensitäten, wird in Kapitel 7 das
OPCPA-System weiter verstärkt. Die spektrale Verbreiterung in einer gas-gefüllten Hohlfaser
erzeugt ein Kontinuum über drei optische Oktaven. Dessen spektrale Phase wird im Folgen-
den charakterisiert und zeigt Selbstkompression bei einer Wellenlänge von 1.3 μm. Der Prozess
erzeugt TE-phasen-stabile Pulse kürzer also zwei optische Zyklen, welche die kürzesten und
intensivsten darstellen, die in diesem Bereich bislang erzeugt wurden.
Weiterhin zeigt die spektrale Verbreiterung im Infraroten besondere Merkmale. Speziell die Gen-
eration von ungeraden Harmonischen niedriger Ordnung und deren Kreuz-Phasen-Modulation
zeigen sich als dominante Prozesse, welche den Einfluss der Eingangsbandbreite minimieren.
Eine experimentelle Untersuchung demonstriert dann, dass auch potentiell effizientere infrarote
OPCPA Systeme mit deutlich längeren Pulsen ähnliche spektrale Bandbreiten erzeugen können.
Die Komprimierung dieser sollte in der nahen Zukunft zu Hochfeld-Anwendungen mit infraroten
Feldtransienten und synthetisierten elektrischen Feldern mit Sub-Zyklus Merkmalen führen.
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Yan, Wenjing. "Spin transport in few-layer graphene." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708038.
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Cherry, Donna J., and John G. Orme. "Finding the Vital Few Foster Mothers." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/7655.
Full textAbstract:
Background and Purpose: Many foster parents serve briefly, and foster and adopt few children. This makes it difficult to ensure the placement, care, stability, and well-being of foster children. Rather than focus on this majority of foster parents, it may be more useful to understand highly productive foster parents. The Pareto Principle provides a useful conceptual framework for doing this. This principle originates from economics and has empirical support in other fields. It also is known as the 80-20 rule or the Vital Few and states that roughly 80% of effects come from 20% of causes. This presentation will report research that identified such a group of foster parents and will describe their characteristics.
Methods: In Study 1 we used a cross-sectional design and a national non-probability sample of 304 non-kinship foster mothers. In Study 2 we used data from the National Survey of Current and Former Foster Parents (NSC&FFP), which included a national probability sample of 876 non-kinship foster families. We used latent class analysis (LCA) to identify discrete subgroups of foster families based on number of children fostered; years fostered; and number of foster children in home at the time of study participation. Study 1 also included number of foster children adopted and number removed at foster parents' request. In Study 1 we also examined differences between subgroups in the quality of care provided.
Results: LCA revealed two classes: 21% and 79% of the sample in Study 1, and 19% and 81% in Study 2. We refer to the smaller group as the Vital Few and the larger as the Useful Many. Vital Few: families fostered 73% and 74% of children in Study 1 and 2, respectively; 10 to 11 times more children than the Useful Many, despite having fostered only two to three times longer. Also, in both studies the Vital Few had 50% more foster children in their homes. Finally, the Vital Few in Study 1 had adopted twice as many children and requested removal rate was of one-half.
In Study 1 we regressed class membership on quality of care indicators using logistic regression. The odds of being in the Vital Few were higher for mothers who: were less likely to use psychological control in parenting or inconsistent parenting; had less need for social readjustment; had more time to foster; and anticipated more help with fostering from professionals. Mothers who anticipated more help with fostering from kin were less likely to be in the Vital Few.
Conclusions and ImplicationsFindings suggest that a disproportionately small percentage of foster parents care for most foster children. Understanding the characteristics of these resilient Vital Few can inform recruitment and retention efforts and the designation of other limited resources. Embracing the phenomenon of the Vital Few can reduce frustration of workers and provide more positive and realistic expectations of foster parents. Further research on the Vital Few is warranted to assess the motivations of this group, the quality of care provided, and outcomes of children fostered by these families.
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Che, Shi. "Quantum Transport in Few-layer Graphene." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574864398913631.
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Pax, Paul Henry 1958. "Few-atom effects in atom optics." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/288794.
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Despite the many advances and achievements in the fields of atom optics and atom cooling, there remains a wealth of dynamical detail to be filled in. While the main features of the important phenomena of atomic cooling, trapping and manipulation by electromagnetic fields are well understood, there are interesting subsidiary effects that are worth our attention. An example, which we discuss in Ch. 5 is the discovery that atomic diffusion in optical lattices may not follow the normal diffusion equation. The work reported in this dissertation represents an investigation into possible few-body effects in some atom optical configurations of interest. The effects of indistinguishability, through the exchange force, on atomic diffraction by standing wave light fields is considered in Ch. 2. In Ch. 3, after a brief overview of atomic collisions in light fields, we look at the role that the dipole-dipole interaction might play, again in atomic diffraction. Chapters 4 and 5 are concerned with optical lattices, and lay the ground work for a study of the effect of the dipole-dipole interaction on the dynamics of atoms confined in such lattices.
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Maheswari, Dhiraj. "QCD Process in Few Nucleon Systems." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3795.
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One of the important issues of Quantum Chromodynamics (QCD) - the fundamental theory of strong interaction, is the understanding of the role of the quark-gluon interactions in the processes involving nuclear targets. One direction in such studies is to explore the onset of the quark gluon degrees of freedom in nuclear dynamics. The other direction is using the nuclear targets as a “micro-labs” in studies of the QCD processes involving protons and neutrons bound in the nucleus. In the proposed research, we work in both directions considering high energy photo- and electro-production reactions involving deuteron and 3 He nuclei.
In the first half of the research, we study the high energy break-up of the 3 He nucleus, caused by a incoming photon, into a proton-deuteron pair at the large center of mass scattering angle. The main motivation of the research is the theoretical interpretation of recent experimental data which revealed the unprecedentedly large exponent s −17 , for the energy dependence of the differential cross section. In the present research, we extend the theoretical formalism of the hard QCD rescattering model to calculate energy and angular dependences of the absolute cross section of the γ 3 He → pd reaction in high momentum transfer limit.
The second half of the research explores the deep-inelastic scattering of a polarized electron off the polarized deuteron and 3 He nuclei, to explore the quark-gluon structure of polarized neutron. The main reason of using deuteron is that it is the most simple and best understood nucleus. While the reason of using polarized 3 He as an effective polarized neutron target is that because of the Pauli-principle, the two protons in the target are in the opposite spin states and thus the neutron has all the polarization of the 3 He nucleus. However this approximation is exact only for the S-state and becomes less accurate with the increase of the internal momentum of the bound nucleons in the nucleus. There are several planned experiments which will be performed during next few years at the kinematics in which the internal momenta of the probed neutron cannot be neglected. Therefore, for the reliable interpretation of the data, all the nuclear effects, especially the effects related to the relativistic treatment of high momentum component of the nuclear wave function, should be taken into account. In this work, we developed a comprehensive theoretical framework for calculation of the all relevant nuclear effects that will allow the accurate extraction of the neutron data from deepinelastic scattering involving deuteron and 3 He targets.
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Chiotti, Tony. "A Few More Words to Part." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2349.
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This is a collection of creative nonfiction writing. It includes an essay on capturing experience and perception, a piece of immersion journalism covering the inhabitants of a game store, and various examples of memoir.
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Zhang, Xiaoying. "Contrast improvement of few-cycle pulses." Thesis, Umeå universitet, Institutionen för fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-165565.
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The intense few-cycle laser pulses play an important role in the investigations of laser-plasma interaction. However, one of the biggest challenges in their generation is the reduction of temporal intensity contrast by introducing undesired pre-pulses and a long pedestal. Two techniques were investigated in this work to improve the contrast. First, the crossed-polarized wave (XPW) generation was optimized to get clean pulse. The conditions for XPW were optimized including crystal thickness and maximal background pressure in the vacuum cell. Second, the method of elliptical polarization rotation (EPR) in a gas-filled hollow-core fiber (HCF) was implemented to produce both broadened and cleaned pulse, since its setup is much simpler. For the tested EPR-based nonlinear filter, the spectral smoothening and broadening were obtained. The contrast of cleaned pulse was characterized providing 2 order of magnitude contrast enhancement, while it had a high average power of 80 mW. The EPR-based nonlinear filter is a promising simplified technique in the development of intense few-cycle lasers.
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Hakimi, Shirin. "Exact Diagonalization of Few-electron Quantum Dots." Thesis, Linnaeus University, School of Computer Science, Physics and Mathematics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-2550.
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<p>We consider a system of few electrons trapped in a two-dimensional circularquantum dot with harmonic confinement and in the presence of ahomogeneous magnetic field, with focus on the role of e-e interaction. Byperforming the exact diagonalization of the Hamiltonian in second quantization,the low-lying energy levels for spin polarized system are obtained. The singlet-triplet oscillation in the ground state of the two-electron system showing up inthe result is explained due to the role of Coulomb interaction. The splitting ofthe lowest Landau level is another effect of the e-e interaction, which is alsoobserved in the results.</p>
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Dimitroglou, Rizell Georgios. "Knotted Legendrian surfaces with few Reeb chords." Licentiate thesis, Uppsala universitet, Algebra, geometri och logik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-139417.
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Schellingerhout, Nicolaas Willem. "Factorizability in the numerical few-body problem." [S.l] : [Groningen] : [s.n.] ; [University Library Groningen] [Host], 1995. http://irs.ub.rug.nl/ppn/141192240.
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Ališauskas, Skirmantas. "Infrared Few-Cycle Pulse Optical Parametric Amplifier." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20101001_145118-06284.
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Main objective of this thesis is to generate and amplify few cycle pulses in the infrared region. In this thesis, two approaches were introduced for few cycle pulse parametric amplification at 800 nm and 1.5 μm. First approach is dedicated for prospects for increasing average power of OPCPA via multi-beam pumping; the second approach is dedicated for generation of carrier-envelope-phase (CEP) stable high energy (up to tens of millijoules) few-cycle pulses at 1.5 μm.
An experimental investigation of two or three beams-pumped OPCPA system based on type I BBO crystal is presented. The 2nd OPA stage was pumped by two or three pump beams derived from independent Nd:YAG laser amplifiers. The efficiency of interaction was shown to be comparable to that of single-beam pumped OPA and diminishes only slightly due to cascaded parametric diffraction of interacting waves. The effect was observed and its impact on efficiency of parametric amplification process was shown to decrease at larger intersecting angles of pump. In the prospect, the use of multiple lasers for OPA pumping has an appeal for increasing the repetition rate and consequently the average power of an ultrashort pulse laser system. Finally, the concept and realization of hybrid system based on type II KTP OPCPA and filamentation are described. A CEP-stable 1.5 μm OPCPA system with pulse energies up to 12.5 mJ after 4 OPA stages is demonstrated. Furthermore, self-compression of CEP-stable 2.2 mJ, 74.4 fs, 1.57 μm input... [to full text]<br>Disertacijos darbo tikslas – suformuoti ir parametriškai stiprinti kelių optinių ciklų trukmės impulsus infraraudonojoje srityje Šioje disertacijoje buvo tirtos dvi moduliuotosios fazės („čirpuotų“) impulsų parametrinio stiprinimo sistemos, stiprinančios ypač plataus spektro impulsus 800 nm bei 1,5 μm srityse. Pirmoji sistema skirta tirti galimybę didinti lazerinės spinduliuotės vidutinę galią keliais pluoštais kaupinamame parametriniame stiprintuve; antroji sistema skirta kelių optinių ciklų trukmės stabilios fazės impulsų formavimui 1,5 μm srityje.
Disertacijoje aprašomas I tipo parametrinis stiprintuvas, kurio 2-oji pakopa buvo kaupinama dviem arba trimis nepriklausomų lazerinių šaltinių pluoštais. Nustatyta, kad parametrinį stiprintuvą kaupinant keliais pluoštais stebimas naujų erdvinių komponentų atsiradimas, kuriuos sąlygoja parametrinė pakopinė difrakcija, o tai mažina bendrą sistemos energetinio keitimo efektyvumą.. Darbo metu pademonstruota galimybė mažinti parametrinės difrakcijos sąlygotus nuostolius parametriniame stiprintuve derinant kampus tarp kaupinimo pluoštų. Taip pat pristatomas alternatyvus būdas formuoti didelės energijos (kelių dešimčių milidžaulių) kelių optinių ciklų trukmės stabilios fazės impulsus 1,5 μm srityje. Būdas paremtas sąlyginai siauro spektro 1,5 μm srityje stiprinimu II tipo KTP kristale bei spektro plėtra inertinėse dujose po stiprinimo. 4 pakopų parametriniame stiprintuve pasiekta iki šiol didžiausia 12,5 mJ impulso energija 1,5 μm... [toliau žr. visą tekstą]
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Tarbutt, Michael Roy. "Spectroscopy of few-electron highly charged ions." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365339.
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Chipperfield, Luke Edward. "High harmonic generation with few-cycle pulses." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487550.
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This thesis studies the response of atoms and molecules to intense few-cycle laser pulses. It is the extremely high frequency dipole radiation generated from such a response that is of interest, both for its exploitation towards generating isolated attosecond pulses and because of the information such radiation contains concerning the laser pulse and electronic wavefunction responsible for its generation. Using a variety of models the process of high order harmonic generation in single atoms is studied in detail to reveal its underlying structure. The high harmonic spectrum is formed from bursts of radiation released every half-cycle of the laser field. The sensitivity of this half-cycle radiation to the precise waveform of the laser field is investigated. In particular the implications of these sensitivities to the stability of attosecond pulse production is studied. The work on single atom high harmonic generation is utilised towards investigations into the high harmonic generation from a volume of atoms. Propagation of the fields through such a volume greatly affects the final spectrum due to phase-matching. A new phenomenon is presented due to this phase-matching which leads tdthe manifestation of half-cycle cut-offs in the propagated spectra. A powerful new technique for measuring few-cycle pulse properties, utilising these half-cycle cut-offs, is developed and demonstrated. It is found capable of measuring the absolute carrier-envelope phase of the driving laser field to within 50 mrad, the highest accuracy of such a measurement achieved to date. The use of spatio-spectral filtering for isolating a half-cycle cut-off is proposed as a method for generating wavelength tunable attosecond pulses. Finally, work is carried out towards the development of a strong field approximation model capable of simulating high harmonic generation from molecules. Such a model is found to be suitable for such calculations and an interesting interference regime is commented on.
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Skrobol, Christoph. "High-Intensity, Picosecond-Pumped, Few-Cycle OPCPA." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-174004.
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Bazak, Betzalel, Moti Eliyahu, and Kolck Ubirajara van. "Effective field theory for few-boson systems." AMER PHYSICAL SOC, 2016. http://hdl.handle.net/10150/621539.
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We study universal bosonic few-body systems within the framework of effective field theory at leading order (LO). We calculate binding energies of systems of up to six particles and the atom-dimer scattering length. Convergence to the limit of zero-range two-and three-body interactions is shown, indicating that no additional few-body interactions need to be introduced at LO. Generalizations of the Tjon line are constructed, showing correlations between few-body binding energies and the binding energy of the trimer, for a given dimer energy. As a specific example, we implement our theory for He-4 atomic systems and show that the results are in surprisingly good agreement with those of sophisticated He-4 - He-4 potentials. Potential implications for the convergence of the EFT expansion are discussed.
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Wu, Menghua M. Eng Massachusetts Institute of Technology. "Few-shot text classification with distributional signatures." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/130200.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, May, 2020<br>Date of graduation confirmed by MIT Registrar Office. "May 2020." Cataloged from student-submitted PDF of thesis.<br>Includes bibliographical references (pages 18-21).<br>We explore meta-learning for few-shot text classification. Meta-learning has shown strong performance in computer vision, where low-level patterns are transferable across learning tasks. However, directly applying this approach to text is challenging-lexical features highly informative for one task may be insignificant for another. Thus, rather than learning solely from words, our model also leverages their distributional signatures, which encode pertinent word occurrence patterns. Our model is trained within a meta-learning framework to map these signatures into attention scores, which are then used to weight the lexical representations of words. We demonstrate that our model consistently outperforms prototypical networks learned on lexical knowledge (Snell et al., 2017) in both few-shot text classification and relation classification by a significant margin across six benchmark datasets (20.0% on average in 1-shot classification).<br>by Menghua Wu.<br>M. Eng.<br>M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Золотова, Світлана Григорівна, Светлана Григорьевна Золотова, and Svitlana Hryhorivna Zolotova. "A few practical ideas about teaching eap." Thesis, Видавництво СумДУ, 2012. http://essuir.sumdu.edu.ua/handle/123456789/25967.
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Teaching English for academic purposes – EAP - aims to provide students with the integrated language skills: to develop their general and professionally- oriented communicative language competences in English. Keeping in mind professional needs of postgraduates and Master’s students in Ukrainian higher educational institutions, we recognise that their learning outcome level may be required for highly verbal specialism, which will ensure their independent English language communicative competence to function effectively in their academic and professional fields. In the process of growing international academic mobility this level for postgraduates and Master’s students opens up the opportunity for Ukrainian universities to join the European Higher Education Area. Speaking about teaching techniques we often think about methods – the theoretical principles and classroom practices. Modern educators propose some practical ideas on how to improve student’s academic vocabulary, grammar, academic skills in reading and using discourse markers, and academic skills in making presentations.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/25967
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Orme, John G., Donna J. Cherry, and Jason D. Brown. "Against All Odds: Vital Few Foster Families." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/7637.
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There is a small, methodologically diverse body of research indicating that approximately 20% of families provide disproportionate amounts of foster caregiving, place fewer restrictions on characteristics of children they are willing to foster and actually do foster, and provide caregiving environments as good as or better than those provided by other foster families. Cherry and Orme (2013) conceptualized this phenomenon in terms of the Pareto Principle, also known as the 80-20 rule or the Vital Few, and they refer to these 20% of families as the Vital Few and the remaining 80% as the Useful Many. This review will examine and synthesize the available research on Vital Few foster families and explore next steps in the development of this body of research.
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Depret-Guillaume, James Serge. "Optimal Point Sets With Few Distinct Triangles." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/91425.
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In this thesis we consider the maximum number of points in $mathbb{R}^d$ which form exactly $t$ distinct triangles, which we denote by $F_d(t)$. We determine the values of $F_d(1)$ for all $dgeq3$, as well as determining $F_3(2)$. It was known from the work of Epstein et al. cite{Epstein} that $F_2(1) = 4$. Here we show somewhat surprisingly that $F_3(1) = 4$ and $F_d(1) = d + 1$, whenever $d geq 3$, and characterize the optimal point configurations. We also show that $F_3(2) = 6$ and give one such optimal point configuration. This is a higher dimensional extension of a variant of the distinct distance problem put forward by ErdH{o}s and Fishburn cite{ErdosFishburn}.<br>Master of Science<br>In this thesis we consider the following question: Given a number of triangles, t, where each of these triangles are different, we ask what is the maximum number of points that can be placed in d-dimensional space, such that every triplets of these points form the vertices of only the t allowable triangles. We answer this for every dimension, d when the number of triangles is t = 1, as well as show that when t = 2 triangle are in d = 3-dimensional space. This set of questions rises from considering the work of Erd˝os and Fishburn in higher dimensional space [EF].
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Kimmel, Tim. "Basic training for a few good men." Theological Research Exchange Network (TREN), 1995. http://www.tren.com.
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Cifuentes, Manuel Valiente. "Few quantum particles on one dimensional lattices." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16191.
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Der aktuelle experimentelle Fortschritt bei der Manipulation ultrakalter Atome mit Licht löst gegenwärtig ein großes Interesse an der Physik entarteter Quantengase und der niederenergetischen Streuung weniger Teilchen aus. Insbesondere ist es möglich, nahezu perfekte periodische Potenziale sogenannte optische Gitter, zu generieren. Die Untersuchung des Verhaltens weniger Quantenteilchen in einem eindimensionalen Gitter ist Thema dieser Arbeit. Der Großteil der Ergebnisse ist im Rahmen der tight-binding-Näherung erhalten worden, welche eine exakt numerische oder analytische Behandlung ermöglicht. Für das Zwei-Körper Problem werden theoretische Methoden entwickelt, um stationäre Streuzustände und gebundene Zustände zu berechnen, und diese werden verallgemeinert, um exakte Ergebnisse für beliebige Wechselwirkungen and Teilchenstatistiken zu erhalten. Der Quantentransport von einem und zwei Teilchen wird auch berücksichtigt. Das Problem der Bindung und Streuung dreier identischer Bosonen wird eingehend betrachtet, wobei neuartige Typen von gebundenen Zuständen entdeckt wurden. Schließlich werden andere Gittersysteme studiert, indem Methoden vorgestellt werden, die mit den für das Zwei-Körper Problem entwickelten Methoden eng verwandt sind.<br>There is currently a great interest in the physics of degenerate quantum gases and low-energy few-body scattering due to the recent experimental advances in manipulation of ultracold atoms by light. In particular, almost perfect periodic potentials, called optical lattices, can be generated. The physics of few quantum particles on a one-dimensional lattice is the topic of this thesis. Most of the results are obtained in the tight-binding approximation, which is amenable to exact numerical or analytical treatment. For the two-body problem, theoretical methods for calculating the stationary scattering and bound states are developed, and are generalized to obtain exact results for arbitrary interactions and particle statistics. Quantum transport of one and two particles is also considered. The problem of binding and scattering of three identical bosons is studied in detail, finding novel types of bound states. Finally, other lattice systems are studied by introducing methods closely connected with the methods developed for the two-body problem.
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Faoro, Riccardo. "Few-body interactions in cold Rydberg atoms." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS180/document.
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L’objectif de cette thèse est l’étude des différents aspects de l’interaction à quelques corps entre des atomes de Rydberg froids. Cette thèse a été réalisée dans le cadre d’une cotutelle entre l’Université Paris-Saclay et l’Université de Pise en travaillant sur deux différents montages expérimentaux sur des atomes de Rydberg froids : respectivement sur le Cs au Laboratoire Aimé Cotton et sur le Rb au département de Physique de l’Université de Pise. Au Laboratoire Aimé Cotton nous avons démontré l’existence des nouvelles interactions à quelques corps dans un gas gelé d’atomes de Rydberg. Ces nouvelles résonances sont la généralisation des résonances de Förster bien connues dans le domaine des atomes de Rydberg. Ces résonances agissent sur les degrés de liberté interne des atomes de Rydberg et ont l’effet d’un transfert résonant d’énergie et de population comme dans le cas des FRET (Fluorescence Resonance Energy Transfer). Comme dans le cas de la résonance de Förster à deux corps, les résonances FRET à trois corps sont accordées à la résonance avec un champ électrique externe et peuvent être observées pour différents nombres quantique principaux. Les effets à trois corps sont observés en absence de tout effet à deux corps et sont qualifiés de Borroméens. La présence d’un champ externe peut générer d’autres résonances entre atomes de Rydberg qui sont interdites en absence de champ électrique. Ces résonances, qu’on peut qualifier des résonances quasi-interdites, sont dues à un couplage dipole-dipole de type Förster. Nous avons identifié toutes ces résonances liées au couplage entre les niveaux de multiplicité de n différents.Dans le montage expérimental à Pise on a étudié les effets mécaniques liés à la répulsion van der Waals entre atomes de Rydberg. Nous avons étudié l’expansion due à l’interaction van der Waals dans une chaîne 1D des atomes de Rydberg de Rb qui ont étés excités avec une excitation laser hors résonance. La comparaison entre les différents désaccords de l’excitation laser démontre le rôle central joué par l’interaction van der Waals<br>The aim of this thesis is to investigate different aspects of few-body interactions in cold Rydberg atoms. It has been realized in a co-tutelle program between the University of Paris-Saclay and the University of Pisa working on two different experimental set ups: one at Laboratoire Aimé Cotton on cold Cs Rydberg atoms and a second at Physics Department of Pisa on cold Rb Rydberg atoms. In Laboratoire Aimé Cotton we demonstrated the existence of new few-body interactions we observed in a frozen Rydberg gas of Cs atoms. These new resonances are a generalization of already known two-body Förster resonances. They act on the internal degrees of freedom of the Rydberg atoms leading to a resonant energy transfer analogous to the one in FRET (Fluorescence Resonance Energy Transfer). In analogy with Förster resonance, three-body FRETs are tuned with an external electric field and can be observed for different principal quantum number. The three-body interaction appeared in the absence of any two-body ones and for this reasons it has a Borromean character. The presence of this external electric field leads to additional resonances between Rydberg atoms supposedly forbidden. These resonances, we call quasi-forbidden Förster resonances, are due to dipole-dipole interaction as in the case of Förster resonance. We investigated these resonances finding a large number close to the allowed two-body and three-body FRET. A precise study was necessary in order to identify and discriminate these resonances from the allowed ones.In the experiment in Pisa we instead focus our attention on the mechanical effect of van der Waals repulsion between Rydberg atoms. We studied the spatial expansion due to a van der Waals interaction in a 1D chain of Rb Rydberg atoms excited with an off-resonant laser excitation. The comparison of the spatial expansion for different detuning of the laser excitation reveals the central role of the van der Waals interaction whose strength is equal to the detuning of the laser excitation
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Potier, Joris. "A few things about hyperimaginaries and stable forking." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/394029.
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The core of this PhD dissertation is basically twofold :
On one hand, I get some new results on the relationship between compact groups and bounded hyperimaginaries, extending a little bit the classical results of Lascar and Pillay in Hyperimaginaries And Automorphism Groups.
On the other hand, I prove some new results around the so called "stable forking" property, more specifically that a simple theory T has stable forking if Teq has. Quite surprisingly, the proof is not so straigtforward.<br>En este texto se trata, por una parte, de la relación entre grupos compactos e hiper-imaginarios acotados, y por otra parte se prueba que una teoría T tiene la propiedad de bifurcación estable si i solo si Teq la tiene.
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Schlackow, Iryna. "Classes of C(K) spaces with few operators." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:e16273c8-c5fd-4a68-a9ca-cd4edb350c5c.
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We investigate properties of Koszmider spaces. We show that if K and L are compact Hausdor spaces with no isolated points, K is Koszmider and C(K) is isomorphic to C(L), then K and L are homeomorphic and, in particular, L is also Koszmider. We also analyse topological properties of Koszmider spaces and show that a connected Koszmider space is strongly rigid. In addition to Koszmider spaces, we introduce the notion of weakly Koszmider spaces. Having established an alternative characterisation thereof, we show that, while it is evident that every Koszmider space is weakly Koszmider, the reverse implication does not hold. We also prove that if C(K) and C(L) are isomorphic and K is weakly Koszmider, then so is L. However, if K is Koszmider, there always exists a non-Koszmider space L such that C(K) and C(L) are isomorphic. In the second part of the thesis we present two separable Koszmider spaces the construction of which does not use any set-theoretical assumptions except for the usual (ZFC) axioms. The first space is zero-dimensional, being the Stone space of a Boolean algebra. The second construction results in a separable connected Koszmider space.
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Gomery, Rebecca. "Antisymmetrisation of few-body models for light nuclei." Thesis, University of Surrey, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538033.
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Pavitt, David. "Few-layer transition metal chloride graphene intercalation compounds." Thesis, University of London, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603531.
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Few-layer transition metal chloride graphene intercalation compounds have becJI fabricated by the mechanical exfoliation of graphite intercalation compounds (GTCs) containing CoC12 , NiCh, CuCl2 , MnCh and FeC13 . The number of graphene layers and the distribution of the intercalate in the few-layer graphene intercalation compounds (FLGICs) have been characterised using the optical contrast of the FLGICs against the Si02 substrate and the G-peak of the Raman spectrum. FLGICs containing CL single intercalate layer surrounded by two graphene layers have been fabricated and characterised, which are an ideal system to study 2D magnetic phase transitions.
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Bai, Neng. "Mode-Division Multiplexed Transmission in Few-mode Fibers." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5761.
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As a promising candidate to break the single-mode fiber capacity limit, mode-division multiplexing (MDM) explores the spatial dimension to increase transmission capacity in fiber-optic communication. Two linear impairments, namely loss and multimode interference, present fundamental challenges to implementing MDM. In this dissertation, techniques to resolve these two issues are presented. To de-multiplex signals subject to multimode interference in MDM, Multiple-Input-Multiple-Output (MIMO) processing using adaptive frequency-domain equalization (FDE) is proposed and investigated. Both simulations and experiments validate that FDE can reduce the algorithmic complexity significantly in comparison with the conventional time-domain equalization (TDE) while achieving similar performance as TDE. To further improve the performance of FDE, two modifications on traditional FDE algorithm are demonstrated. i) normalized adaptive FDE is applied to increase the convergence speed by 5 times; ii) master-slave carrier recovery is proposed to reduce the algorithmic complexity of phase estimation by number of modes. Although FDE can reduce the computational complexity of the MIMO processing, due to large mode group delay (MGD) of FMF link and block processing, the algorithm still requires enormous memory and high hardware complexity. In order to reduce the required tap length (RTL) of the equalizer, differential mode group delay compensated fiber (DMGDC) has been proposed. In this dissertation, the analytical expression for RTL is derived for DMGDC systems under the weak mode coupling assumption. Instead of depending on the overall MGD of the link in DMGD uncompensated (DMGDUC) systems, the RTL of DMGDC systems depend on the MGD of a single DMGDC fiber section. The theoretical and numerical results suggest that by using small compensation step-size, the RTL of DMGDC link can be reduced by 2 orders of magnitude compared to DMGDUC link. To compensate the loss of different modes, multimode EDFAs are presented with re-configurable multimode pumps. By tuning the mode content of the multimode pump, mode-dependent gain (MDG) can be controlled and equalized. A proto-type FM-EDFA which could support 2 LP modes was constructed. The experimental results show that by using high order mode pumps, the modal gain difference can be reduced. By applying both multimode EDFA and equalization techniques, 26.4Tb/s MDM-WDM transmission was successfully demonstrated. A brief summary and several possible future research directions conclude this dissertation.<br>Ph.D.<br>Doctorate<br>Optics and Photonics<br>Optics and Photonics<br>Optics
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Wark, H. M. "Banach spaces with few operators and multiplier results." Thesis, University of Oxford, 1997. http://ora.ox.ac.uk/objects/uuid:467c7ec7-d9f1-41cd-9fa9-0f97894ac6a5.
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The construction of a non-separable reflexive Banach space on which every operator is the sum of a scalar multiple of the identity operator and an operator of separable range is presented. Using a result of Rao, a sufficient condition is given for Banach spaces with smooth norms to be decomposable. It is shown that operators on Banach spaces of co-dimension one in their biduals are the sum of a scalar multiple of the identity operator and a weakly compact operator. The Banach spaces of bounded operators L(1<sup>1</sup>, 1<sup>p</sup>) (1<p<ꝏ) and L(1<sup>p</sup>, 1<sup>r</sup>), 1 < p ≤ r ≤ p<sup>1</sup> < ꝏ, where 1/p + 1/p<sup>1</sup> = 1, are shown to be primary. The spaces of bounded diagonal operators and compact diagonal operators on a seminormalized Schauder basis β, the multiplier algebras L<sup>d</sub>(X, β) and K<sub>d</sub>(X, β), are introduced and studied. New examples of these multiplier algebras are presented and a theorem of Sersouri is extended. A necessary and sufficient condition is given for c<sub>o</sub> to embed in K<sub>d</sub>(X, β). A sufficient condition is given on a semi-normalized Schauder basis β of a reflexive hereditarily indecomposable Banach space Y to ensure that K<sub>d</sub>(Y, β) has the RNP. It is shown that the algebra L<sub>d</sub>(X, β) is semisimple and that on the algebra K<sub>d</sub>(X, β) derivations are automatically continuous. By representing diagonal operators as stochastic processes a general method of constructing multiplier algebras is given. A non trivial multiplier invariance for the normalized Haar basis of L<sup>1</sup>[0,1] is proved.
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Ralley, Kevin. "Few-photon transport in quasi-one-dimensional geometries." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4316/.
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An analysis of some aspects of photon transport through cavities and emitters embedded in a one-dimensional geometries is presented. The concept of photon blockade is defined for few-photon states interacting with a single two-level atom and the strength of achievable blockade is calculated in this setting. A brief review of some promising schemes for achieving photon blockade from the literature is also provided. The conflict between linear and nonlinear optical processes is studied for a novel version of the famous Hong-Ou-Mandel effect in a photonic waveguide with a side-coupled two-level emitter.
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Chaudhary, Irfan Ullah 1970. "Applications of group theory to few-body physics." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30157.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.<br>Includes bibliographical references (leaves 257-262).<br>Over the past fifteen years, there have been persistent claims of anomalous nuclear reactions in condensed matter environments. A Unified Model [38] has been proposed to systematically account for most of these anomalies. However, all the work done so far has used simple scalar nuclear Hamiltonians. In this thesis, we develop the tools necessary to use a realistic nuclear Hamiltonian in the Unified Model. A natural way to include a realistic nuclear potential in the Unified Model is via the method of coupled-channel equations. The phenomenological nuclear interaction chosen is the Hamada-Johnston potential [40]. The major portion of the thesis is devoted to deriving the coupled-channel equations with explicit symmetry constraints for the Hamada-Johnston potential. A critical input in this derivation is the calculation of the matrix elements of the various channels. We develop a systematic method, based on group theory, for calculating matrix elements of few-body correlated spatial wavefunctions. This method can, in some sense, be considered a generalization of Racah's viewpoint [17] of calculating shell-model matrix elements. Towards the end, two related, but somewhat different topics are explored. Firstly, a simple phonon-coupled nuclear reaction, the photodisintegration of the deuteron, is investigated. While no observable results are computed, this work should be considered a first step in calculating the effects of the lattice on nuclear reactions. Secondly, Lie algebra theory is used to understand the coherent decay, from the highest symmetry state in N-level systems, in terms of the usual Dicke [21] algebra.<br>by Irfan Ullah Chaudhary.<br>Ph.D.
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Siddiqui, Aleem 1977. "Few-cycle and cavity-enhanced optical parametric amplification." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79494.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 179-185).<br>Optical parametric amplifiers have emerged as important optical sources by extending the properties of few-cycle laser sources, which exist only in materials with sufficiently large gain bandwidths, to wide array of spectral ranges. The work reported in this thesis relates to two areas for the continued development of optical parametric amplification based sources. First, we present a white light seeded, carrier-envelope stable, degenerately pumped OPA producing near tranform-limited sub 7 fs , 3 [mu]J pulses at the driver wavelength from a long pulse, non-CEP stable Ti:sapphire regenerative amplifier. Problems to the spectral phase jump at the driver wavelength, 800 nm, were avoided by using a near infrared OPA to produce white light continuum down to 800 nm where the spectral phase is smooth. Secondly, enhancement cavities are used in conjunction with parametric amplifiers resulting in a new technique entitled, cavity-enhanced optical parametric chirped-pulse amplification (C-OPCPA). C-OPCPA increases the capabilities of nonlinear crystals and can allow continued scaling of parametric amplifier systems to high repetition rate. This work contains the first theoretical and experimental investigation of C-OPCPA. Numerically, passive pump pulse shaping of the intracavity pump power is shown to enable octave spanning gain. Experimentally, a first proof-of-principle experiment demonstrates a 78 MHz C-OPCPA with more than 50% conversion with under 1 W of incident pump power. A comparison to a single pass system shows improvements in the C-OPCPA of orders of magnitude in conversion efficiency and 3 fold increase in phase matching bandwidth in 10 and 20 mm periodically poled lithium niobate phase matched for parametric amplification with 1030 nm pump wavelength and a 1550 nm signal wavelength. A Yb-fiber laser based CPA system producing up to 5 W of 500 fs pulses comprises the pump source, and a Er-fiber laser the signal.<br>by Aleem Mohammad Siddiqui.<br>Ph.D.
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Kuo, Michael. "Learning visual object categories from few training examples." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/66430.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 73-74).<br>During visual perception of complex objects, humans fixate on salient regions of a particular object, moving their gaze from one region to another in order to gain information about that object. The Bayesian Integrate and Shift (BIAS) model is a recently proposed model for learning visual object categories that is modeled after the process of human visual perception, integrating information from within and across fixations. Previous works have described preliminary evaluations of the BIAS model and demonstrated that it can learn new object categories from only a few examples. In this thesis, we introduce and evaluate improvements to the learning algorithm, demonstrate that the model benefits from using information from fixating on multiple regions of a particular object, evaluate the limitations of the model when learning different object categories, and assess the performance of the learning algorithm when objects are partially occluded.<br>by Michael Kuo.<br>M.Eng.
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Orme, John G., and Donna J. Cherry. "The Vital Few foster parents: Replication and extension." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/etsu-works/7638.
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The Pareto Principle, also known as the 80-20 rule or the Vital Few, has been successfully used as a framework to identify the small proportion of highly productive foster parents who provide a disproportionate amount of care. This study replicated and extended this research using a nationally representative sample of foster families ( N=. 876) with a focus on willingness to foster, and actually fostering, children with special needs.
Using latent class analysis, two classes of foster parents were identified: one accounted for 19% of respondents and the other 81%. We refer to the former as the Vital Few and the latter as the Useful Many. Vital Few respondents fostered 74.2% of foster children - 11 times more than the Useful Many, although only fostering two times longer. They also had almost 1-1/2 times as many foster children in their homes at the time of the study. Notably, the Vital Few were willing to foster more types of children with special needs and a higher percentage had actually fostered children with each of the seven types of special needs studied. The classes were similar demographically except that Vital Few respondents were less likely to work outside the home and Vital Few mothers were slightly less educated as compared to Useful Many mothers.
This study further validates the utility of the Pareto Principle for understanding foster parents and, by extension, has important implications for the well-being and stability of foster children with special needs. Considerations for supporting the Vital Few, including education and training needs, are discussed.
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Cui, Jie. "Moment Optimization towards Learning Polytopes with Few Facets." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338403274.
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Ray, Taylor J. "Analysis of Side-Polished Few-Mode Optical Fiber." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/89761.
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Side-polished fiber allows access to the evanescent field propagating in the cladding of a few-mode fiber. This cladding mode is analyzed and experimentally validated to further the design of a novel class of fiber optic devices. To do this, specific modes are excited in the polished fiber using a phase-only spatial light modulator to determine spatial mode distribution. Each mode is excited and compared to the expected field distribution and to confirm that higher order modes can propagate through side-polished fiber. Based on each mode’s distribution, a side-polished fiber can be designed so that perturbations on the polished portion of the fiber effect each mode independently. By carefully analyzing the effects of identical perturbations on each mode, it is determined that each mode can be isolated based on the geometry of the polished fiber and careful alignment of the mode field. This research has the potential to advance the development of novel fiber-based sensors and communications devices utilizing mode-based interferometry and mode multiplexing.<br>M.S.<br>Fiber optic devices have seen significant advancement since the realization of the laser and low-loss optical fiber. Modern day fiber optics are commonly utilized for high-bandwidth communications and specialized sensing applications. Utilizing multiple modes, or wave distributions, in a fiber provides significant advantages towards increasing bandwidth for communications and provides potential for more accurate sensing techniques. Significant research has been conducted in both the sensing and communication field, but mode-domain devices have the capability to significantly advance the field of fiber optic devices. This thesis demonstrates the potential for side-polished fiber geometry to effect each mode independently, thus allowing side-polished fiber to be utilized for realizing novel devices such as multiplexing devices and fiber optic sensors.
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Reimann, Sebastian Michael. "Multilingual Zero-Shot and Few-Shot Causality Detection." Thesis, Uppsala universitet, Institutionen för lingvistik och filologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-446516.
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Relations that hold between causes and their effects are fundamental for a wide range of different sectors. Automatically finding sentences that express such relations may for example be of great interest for the economy or political institutions. However, for many languages other than English, a lack of training resources for this task needs to be dealt with. In recent years, large, pretrained transformer-based model architectures have proven to be very effective for tasks involving cross-lingual transfer such as cross-lingual language inference, as well as multilingual named entity recognition, POS-tagging and dependency parsing, which may hint at similar potentials for causality detection. In this thesis, we define causality detection as a binary labelling problem and use cross-lingual transfer to alleviate data scarcity for German and Swedish by using three different classifiers that make either use of multilingual sentence embeddings obtained from a pretrained encoder or pretrained multilingual language models. The source languages in most of our experiments will be English, for Swedish we however also use a small German training set and a combination of English and German training data. We try out zero-shot transfer as well as making use of limited amounts of target language data either as a development set or as additional training data in a few-shot setting. In the latter scenario, we explore the impact of varying sizes of training data. Moreover, the problem of data scarcity in our situation also makes it necessary to work with data from different annotation projects. We also explore how much this would impact our result. For German as a target language, our results in a zero-shot scenario expectedly fall short in comparison with monolingual experiments, but F1-macro scores between 60 and 65 in cases where annotation did not differ drastically still signal that it was possible to transfer at least some knowledge. When introducing only small amounts of target language data, already notable improvements were observed and with the full German training data of about 3,000 sentences combined with the most suitable English data set, the performance for German in some scenarios even almost matches the state of the art for monolingual experiments on English. The best zero-shot performance on the Swedish data was even outperforming the scores achieved for German. However, due to problems with the additional Swedish training data, we were not able to improve upon the zero-shot performance in a few-shot setting in a similar manner as it was the case for German.
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Barnett, Anthony D. "The stability of few-body stellar dynamical systems." Thesis, Glasgow Caledonian University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.688239.
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