181 |
Arktibus ögon : En läromedelsanalys med fokus på läsförståelsestrategierOlsson, Johanna, Olofsson, Anna January 2020 (has links)
Examensarbetet är en läromedelsanalys där syftet är att undersöka hur ett läromedel iämnet svenska för årskurs 1 förhåller sig till läsförståelsestrategier. I arbetet undersöks vilka läsförståelsestrategier som framkommer i läromedlet Arktibus ögon, hur de strategierna kan kopplas till forskningsbaserade modeller som utvecklar läsförståelse och hur läromedlet stämmer överens med läroplanens kunskapskrav för läsförståelse i slutet av årskurs 1. För att få svar på forskningsfrågorna gjordes en innehållsanalys och en litteraturstudie. Litteraturstudien innefattar tre forskningsbaserade läsförståelsemodeller som innehåller läsförståelsestrategier (reciprocal teaching, transactional strategies instruction och concept-oriented reading instruction). Dessa strategier har dokumenterats ge god effekt på läsförståelsen. Examensarbetet utgår från Vygotskijs teori om ett sociokulturellt lärande, som innebär att lärandet ses som något socialt som sker i samspel mellan individer. Resultatet av studien visar att i Arktibus ögon framkommer de läsförståelsestrategier som de tre forskningsbaserade modellerna lyfter fram. Uppgifter i läromedlet som behandlar läsförståelse och läsförståelsestrategier går att koppla till alla delar av kunskapskravet för godtagbara kunskaper i läsförståelse för årskurs 1 (Skolverket 2019a).
|
182 |
Comparing Approximations for Risk Measures Related to Sums of Correlated Lognormal Random VariablesKarniychuk, Maryna 30 November 2006 (has links)
In this thesis the performances of different approximations are compared for a standard actuarial and
financial problem: the estimation of quantiles and conditional
tail expectations of the final value of a series of discrete cash
flows.
To calculate the risk measures such as quantiles and Conditional
Tail Expectations, one needs the distribution function of the
final wealth. The final value of a series of discrete payments in
the considered model is the sum of dependent lognormal random
variables. Unfortunately, its distribution function cannot be
determined analytically. Thus usually one has to use
time-consuming Monte Carlo simulations. Computational time still
remains a serious drawback of Monte Carlo simulations, thus
several analytical techniques for approximating the distribution
function of final wealth are proposed in the frame of this thesis.
These are the widely used moment-matching approximations and
innovative comonotonic approximations.
Moment-matching methods approximate the unknown distribution
function by a given one in such a way that some characteristics
(in the present case the first two moments) coincide. The ideas of
two well-known approximations are described briefly. Analytical
formulas for valuing quantiles and Conditional Tail Expectations
are derived for both approximations.
Recently, a large group of scientists from Catholic University
Leuven in Belgium has derived comonotonic upper and comonotonic
lower bounds for sums of dependent lognormal random variables.
These bounds are bounds in the terms of "convex order". In order
to provide the theoretical background for comonotonic
approximations several fundamental ordering concepts such as
stochastic dominance, stop-loss and convex order and some
important relations between them are introduced. The last two
concepts are closely related. Both stochastic orders express which
of two random variables is the "less dangerous/more attractive"
one.
The central idea of comonotonic upper bound approximation is to
replace the original sum, presenting final wealth, by a new sum,
for which the components have the same marginal distributions as
the components in the original sum, but with "more dangerous/less
attractive" dependence structure. The upper bound, or saying
mathematically, convex largest sum is obtained when the components
of the sum are the components of comonotonic random vector.
Therefore, fundamental concepts of comonotonicity theory which are
important for the derivation of convex bounds are introduced. The
most wide-spread examples of comonotonicity which emerge in
financial context are described.
In addition to the upper bound a lower bound can be derived as
well. This provides one with a measure of the reliability of the
upper bound. The lower bound approach is based on the technique of
conditioning. It is obtained by applying Jensen's inequality for
conditional expectations to the original sum of dependent random
variables. Two slightly different version of conditioning random
variable are considered in the context of this thesis. They give
rise to two different approaches which are referred to as
comonotonic lower bound and comonotonic "maximal variance" lower
bound approaches.
Special attention is given to the class of distortion risk
measures. It is shown that the quantile risk measure as well as
Conditional Tail Expectation (under some additional conditions)
belong to this class. It is proved that both risk measures being
under consideration are additive for a sum of comonotonic random
variables, i.e. quantile and Conditional Tail Expectation for a
comonotonic upper and lower bounds can easily be obtained by
summing the corresponding risk measures of the marginals involved.
A special subclass of distortion risk measures which is referred
to as class of concave distortion risk measures is also under
consideration. It is shown that quantile risk measure is not a
concave distortion risk measure while Conditional Tail Expectation
(under some additional conditions) is a concave distortion risk
measure. A theoretical justification for the fact that "concave"
Conditional Tail Expectation preserves convex order relation
between random variables is given. It is shown that this property
does not necessarily hold for the quantile risk measure, as it is
not a concave risk measure.
Finally, the accuracy and efficiency of two moment-matching,
comonotonic upper bound, comonotonic lower bound and "maximal
variance" lower bound approximations are examined for a wide range
of parameters by comparing with the results obtained by Monte
Carlo simulation. It is justified by numerical results that,
generally, in the current situation lower bound approach
outperforms other methods. Moreover, the preservation of convex
order relation between the convex bounds for the final wealth by
Conditional Tail Expectation is demonstrated by numerical results.
It is justified numerically that this property does not
necessarily hold true for the quantile.
|
183 |
Lithium Niobate Acoustoelectric Platforms for Integrated Non-Reciprocal RF MEMS DevicesMatthew J Storey (10285355) 16 March 2021 (has links)
<div>Some of the biggest challenges with analog signal processing at radio frequencies (RF) are: RF loss at the frequency of interest, large enough fractional bandwidth, and sufficient delay. It is difficult to achieve enough delay in radio front ends using a purely electromagnetic approach since it is limited to a fraction of the speed of light. A solution has been the use of acoustic RF devices, such as surface acoustic wave (SAW) delaylines and MEMS filters. For some acoustic RF devices, like high performance Transmit and Receive SAW correlators, the long delays introduce significant propagation losses. These propagation losses can be compensated within the device by integrating a low noise amplifier into the acoustic correlator architecture. This can be accomplished by designing the SAW correlator on a high performance acoustoelectric (AE) platform. The AE effect is a phenomenon where nearby free carriers can interact with a travelling acoustic wave. Free carriers in close proximity to a piezoelectric material can interact with a travelling acoustic wave through its periodic potential. When a drift field is applied, depending on the relative velocity difference between the free carriers and acoustic wave, energy can either be transferred into (amplification) or out of (attenuation) the acoustic wave. </div><div><br></div><div>This thesis investigates the design and feasibility of AE MEMS devices on several Lithium Niobate (LN) platforms. First, the key acoustic and free carrier parameters are discussed and optimized for an ideal high performance AE material stack. In order to debug and analyze the performance of intermediate steps in the process of making high performance AE MEMS devices, three LN-based platforms are used throughout this work. These platforms help further examine some of the key challenges associated with making a high performance AE platform, like wafer bonding, fabrication, device design, and device operating conditions. These material stacks consist of: thin film LN bonded to a silicon wafer (LNOSi), thin film LN bonded to a silicon on insulator wafer (LNOSOI), and epitaxial indium gallium arsenide bonded to a LN wafer (InGaAs-LN).</div><div><br></div><div>The acoustic and piezoelectric performance of SAW devices on the LNOSi and LNOSOI platforms are modeled using COMSOL Multiphysics. A full study is performed to determine the piezoelectric coupling coefficient variation vs. device wavelength, propagation angle, transducer metal, and acoustic mode. A lumped element cross-field Mason model is modified to include substrate conductivity and simulated in Advanced Design System (ADS) software. SAW delaylines are then fabricated with both aluminum (Al) and gold (Au) Interdigital Transducers (IDT) and measured to compare to the simulated results. The analytical AE theory is then presented and calculations are performed to determine the desired (optimum) carrier concentration for AE devices. In addition to the 1D analytical AE model, initial work is done on developing a generalized 2D Finite Element Analysis (FEA) AE modeling scheme in COMSOL. The results for a piezoelectric semiconductor bulk acoustic wave (BAW) resonator and SAW delayline amplifier are presented. </div><div><br></div><div>On the LNOSi platform, gate controlled passive AE delaylines are fabricated and measured to examine the effects of LN bonding on Silicon free carrier concentrations and interface charges. Then, the fabrication and initial measurement results for doped Silicon AE delayline amplifiers are outlined. Based on the device design, the non-reciprocal nature of the AE effect can be used for more than just amplification and loss compensation. Using the InGaAs-LN platform, several classes of AE devices are designed and tested in pulsed mode operation. First, a series of segmented AE delayline amplifiers are measured to look at how the relative AE gain performance and input DC power scale with acoustic frequency, segment unit length, and number of segments. By taking advantage of the non-reciprocal shift in acoustic velocity, a dual-voltage AE delayline phase shifter is designed and tested. Routing of the acoustic waves between parallel delaylines can be accomplished through multistrip couplers (MSC) and can increase the library of possible AE device designs. The simplest example is a 3-port AE switch, which is designed and tested. The demonstration of these AE MEMS devices opens the door to a larger library of non-reciprocal acoustic devices utilizing the AE effect in high performance integrated material platforms.</div>
|
184 |
Meiotická homologní rekombinace a hybridní sterilita / Meiotic homologous recombination and hybrid sterilityGergelits, Václav January 2020 (has links)
(English) Meiotic homologous recombination, homologous chromosomes synapsis, and F1 hybrid sterility (enabling formation of species) are mutually interconnected phenomenons, one being the prerequisite to the latter. In the present thesis, these phenomenons were investigated on a genetic and mechanistic level using a mouse subspecies as a model. Noncrossovers (NCOs, gene conversions), 90% prevalent resolution of Prdm9- determined meiotic double-strand breaks (DSBs), were uniquely identified and characterized on a chromosome-wide level. The mean gene conversion tract length, based on 94 NCOs events, was calculated to be 32 bp. On a local level, the NCOs overlapped the known hotspots of PRDM9-controlled histone trimethylation and DSB formation, indicating their origin in the standard meiotic DSB repair pathway. On chromosome-wide level, NCO and CO distributions differed, in particular COs being relatively preferred over NCOs in subtelomeric regions. A specific subset of nonparental/asymmetric NCOs and COs was underrepresented in our datasets, proposing their problematic repair, hypothetically enabled by sister chromatids, and thus not contributing to indispensable homologous synapsis. Genome-wide crossover (CO) rates, genetically and mechanistically crucial ~10% of DSB repair, were proven to be...
|
185 |
An Exploration of Elementary L2 Learners' Use of Metacognitive StrategiesMcNeel, Michele E. 12 1900 (has links)
This multiple case study examined the experiences of elementary L2 learners who received instruction in either reciprocal teaching or the think aloud strategy (TAS), and identified patterns of use that emerged from participants' employment of the strategies. The three L2 participants took a pre- test and a posttest, were recorded using the strategies, and responded to interview questions about the strategies. Using qualitative data analysis techniques, four themes emerged from analysis of the data, including; talking like a teacher, I know what I know, established strategies, and declines to use the steps in the strategy. Implications from these findings suggest that the discussion facilitated by reciprocal teaching assists elementary L2 participants in better understanding the text and also supports their language acquisition, whereas TAS does not facilitate discussion. Further, even though reciprocal teaching promotes discussion, teacher assistance during discussion is necessary. Finally, it is essential that teachers are mindful of students' understandings of topics and the difficulty of texts used when students are learning the strategies.
|
186 |
Decolonial affordances of a communal heritage platform: A case study of the Reciprocal Research NetworkMaurer, Jason January 2021 (has links)
Museums are increasingly reckoning with their roles in the colonization of Indigenous peoples as they seek to engage diverse forms of participation and justify their social relevance. Many are turning to digital solutions to aid with these endeavors, including digital repatriation/return platforms. How users interact with these platforms to create knowledge and how these platforms contribute to a larger decolonial aspiration is not well understood. In this study, I explore these issues, drawing on postcolonial/decolonial theories and affordance theory, using the Reciprocal Research Network (RRN). The RRN was co-designed by the Museum of Anthropology, U’mista Cultural Society, Musqueam Indian Band, and Stó:lō Nation/Tribal Council to meet the need for museums to involve Indigenous communities in heritage work. With an actor-network theory approach, I interviewed nine stakeholders (users, developers, and steering group members) of the RRN and explored the platform and documents to identify RRN actors’ specific enactments of decolonial aspirations as affordances. My exploration revealed that the RRN is bound as a network by the Item Search, which allowed for multiple entry points into a vast collection of heritage objects. These multiple entryways broke down technical and cultural barriers to and allowed for plurality in interaction with heritage. The RRN also allowed a direct contestation of museums’ data ownership by allowing users to dictate how shared knowledge is used. The RRN also was deeply embedded in Vancouver, BC, and its surrounding area, where multiple points of offline/online interaction allowed for deep explorations of the histories of First Nations peoples and aided in projects aimed at their revival. However, platform logics and museums’ lack of participation in relationship-building threatened the decolonial aspirations of the RRN. Broadly, my findings indicate that the RRN, as a communal heritage platform, is a necessary step towards building relations with Indigenous communities that requires further participation on museums’ part to develop.
|
187 |
MILLIMETER-WAVE FARADAY ROTATION FROM FERROMAGNETIC NANOWIRES AND MAGNETOELASTIC MATERIALSParsa, Nitin 29 August 2019 (has links)
No description available.
|
188 |
THE IMPACT OF DIRECT TO CONSUMER SHIPPING LAWS ON THE SIZE DISTRIBUTION OF WINERIESPesavento, Matthew Todd 30 July 2019 (has links)
No description available.
|
189 |
Collective Commitments Within Cycles of Iterative ImprovementMaddox, Carissa June 07 August 2023 (has links)
No description available.
|
190 |
Irreversibility, heat and information flows induced by non-reciprocal interactionsLoos, Sarah A.M., Klapp, Sabine H.L. 27 April 2023 (has links)
We study the thermodynamic properties induced by non-reciprocal interactions between
stochastic degrees of freedom in time- and space-continuous systems. We show that, under fairly
general conditions, non-reciprocal coupling alone implies a steady energy flow through the system,
i.e., non-equilibrium. Projecting out the non-reciprocally coupled degrees of freedom renders
non-Markovian, one-variable Langevin descriptions with complex types of memory, for which we
find a generalized second law involving information flow.We demonstrate that non-reciprocal
linear interactions can be used to engineer non-monotonic memory, which is typical for, e.g.,
time-delayed feedback control, and is automatically accompanied with a nonzero information flow
through the system. Furthermore, already a single non-reciprocally coupled degree of freedom can
extract energy from a single heat bath (at isothermal conditions), and can thus be viewed as a
minimal version of a time-continuous, autonomous ‘Maxwell demon’.We also show that for
appropriate parameter settings, the non-reciprocal system has characteristic features of active
matter, such as a positive energy input on the level of the fluctuating trajectories without global
particle transport.
|
Page generated in 0.0607 seconds