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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Perceiving and counting sounds : the roles of pitch distance, rhythm and grouping /

Maser, Daryle Jean January 1983 (has links)
No description available.
32

Enhanced sensitivity and speed in photomultiplier tubes

Hallensleben, Sebastian January 2000 (has links)
No description available.
33

The influence of social interaction on the development of cardinality in pre-school children

Linnell, Margaret Elizabeth January 1998 (has links)
No description available.
34

A Neural Model of Call-counting in Anurans

Houtman, David B. 11 October 2012 (has links)
Temporal features in the vocalizations of animals and insects play an important role in a diverse range of species-specific activities such as mate selection, territoriality, and hunting. The neural mechanisms underlying the response to such stimuli remain largely unknown. Two species of anuran amphibian provide a starting point for the investigation of the neurological response to species-specific advertisement calls. Neurons in the anuran midbrain of Rana pipiens and Hyla regilla exhibit an atypical response when presented with a fixed number of advertisement calls. The general response to these calls is mostly inhibitory; only when the correct number of calls is presented at the correct repetition rate will this inhibition be overcome and the neurons reach a spiking threshold. In addition to rate-dependent call-counting, these neurons are sensitive to missed calls: a pause of sufficient duration—the equivalent of two missed calls—effectively resets a neuron to its initial condition. These neurons thus provide a model system for investigating the neural mechanisms underlying call-counting and interval specificity in audition. We present a minimal computational model in which competition between finely-tuned excitatory and inhibitory synaptic currents, combined with a small propagation delay between the two, broadly explains the three key features observed: rate dependence, call counting, and resetting. While limitations in the available data prevent the determination of a single set of parameters, a detailed analysis indicates that these parameters should fall within a certain range of values. Furthermore, while network effects are counter-indicated by the data, the model suggests that recruitment of neurons plays a necessary role in facilitating the excitatory response of counting neurons—although this hypothesis remains untested. Despite these limitations, the model sheds light on the mechanisms underlying the biophysics of counting, and thus provides insight into the neuroethology of amphibians in general.
35

Does carbohydrate counting from diabetes onset improve glycemic control in children and adolescents with type 1 diabetes? : A clinical prospective study with a cross sectional questionnaire.

Jelleryd, Elisabeth January 2016 (has links)
Background Carbohydrate counting is a method used to calculate insulin doses to meals, in the treatment of diabetes type 1. Few studies are available with a clear consensus on its efficacy and effect on anthropometrics in children and adolescents. Aim To evaluate if carbohydrate counting as treatment method in diabetes type 1 improved glycemic control and anthropometrics compared to conventional treatment, one and two years after onset in children and adolescents at Astrid Lindgren children’s hospital. A secondary aim was to explore patients and caregivers perception of insulin dosage to meals with focus on efficacy, time consumption and adherence. Method A clinical prospective study was performed on data collected from the Swedish pediatric quality registry (Swediabkids). Children with diabetes onset between 2010 and 2014 registered at Astrid Lindgren Children’s hospital (n=371) were included and divided into two groups, carbohydrate counters and non-carbohydrate counters. Normal distribution was assumed and parametric tests were performed. The registry data was complemented with a web-based questionnaire providing information on perception of carbohydrate counting, answered by 78 subjects. Results Carbohydrate counting reduced insulin requirements (p<0.001) and eliminated differences between pump- and pen users (p<0.001) as well as differences between boys and girls. Glycemic control was not improved by carbohydrate counting one and two years after diabetes onset (p=0.233, p=0.295). An adverse effect was increased body mass index standard deviation score (BMI-sds) (p=0.044), especially amongst girls (p=0.038). Conclusion Carbohydrate counting lowers insulin requirements with maintained glycemic control. Contradictory, greater weight gain was found in the carbohydrate counting group, especially among girls. A plausible explanation is that carbohydrates have taken focus off protein- and fat intake in combination with a more liberal approach to energy dense foods, causing excess energy intake. The strength of carbohydrate counting does not lie in its ability to lower HbA1c-values but as a helpful tool, which patients are happy to use. / Bakgrund Kolhydraträkning är en metod som används för att beräkna insulindoser till måltider, i behandlingen av diabetes typ 1. Få studier finns för att ge en samlad konsensus gällande dess effekt på glykemisk kontroll och tillväxt hos barn och ungdomar. Syfte Att utvärdera om införandet av kolhydraträkning som behandlingsmetod vid diabetes typ 1 påverkat metabol kontroll och tillväxt i jämförelse med konventionell metod, ett och två år efter diabetesdebut. Ett andra syfte var att utforska patienters och vårdnadshavares uppfattning om insulindosering till måltider med fokus på effektivitet, tidskonsumtion och följsamhet. Metod En klinisk prospektiv studie utfördes med data inhämtad från Nationellt kvalitetsregister för barn och ungdomar med diabetes (Swediabkids). Barn och ungdomar som debuterade med diabetes typ 1 på Astrid Lindgrens barnsjukhus mellan 2010 och 2014 (n=371) inkluderades i studien och delades in i två grupper baserat på debutdatum; kolhydraträknare och icke-kolhydraträknare. Materialet bedömdes som normalfördelat och parametriska test utfördes. En tvärsnittsenkät administrerades till studiedeltagarna för att införskaffa fördjupad information om patienters och vårdnadshavares uppfattning om insulindosering till måltider. Den webbaserade enkäten besvarades av 78 deltagare. Resultat Kolhydraträkning reducerade insulinbehovet (p<0.001) och jämställde insulinbehovet mellan pump- och pennanvändare (p<0.001) liksom skillnader mellan pojkar och flickor inom gruppen. Glykemisk kontroll förändrades inte av kolhydraträkning ett och två år efter debut (p=0.233, p=0.295). En oönskad effekt av kolhydraträkningen var en ökning i BMI-sds (p=0.044), speciellt hos flickor (p=0.038). Slutsats Kolhydraträkning från diabetesdebut sänker insulinbehov med bibehållen glykemisk kontroll. Motsägelsefullt, så fanns en viktökning i gruppen som använde kolhydraträkning, speciellt hos flickor. En möjlig förklaring är att kolhydrater har tagit fokus från protein- och fettintag tillsammans med en mer frikostig syn på energität mat, vilket har orsakat ökat energiintag. Styrkan i kolhydraträkning ligger inte i dess förmåga att förbättra glykemisk kontroll men som ett användarvänligt verktyg som patienterna är nöjda med.
36

CMOS system for high throughput fluorescence lifetime sensing using time correlated single photon counting

Tyndall, David January 2013 (has links)
Fluorescence lifetime sensing using time correlated single photon counting (TCSPC) is a key analytical tool for molecular and cell biology research, medical diagnosis and pharmacological development. However, commercially available TCSPC equipment is bulky, expensive and power hungry, typically requiring iterative software post-processing to calculate the fluorescence lifetime. Furthermore, the technique is restrictively slow due to a low photon throughput limit which is necessary to avoid distortions caused by TCSPC pile-up. An investigation into CMOS compatible multimodule architectures to miniaturise the standard TCSPC set up, allow an increase in photon throughput by overcoming the TCSPC pile-up limit, and provide fluorescence lifetime calculations in real-time is presented. The investigation verifies the operation of the architectures and leads to the selection of optimal parameters for the number of detectors and timing channels required to overcome the TCSPC pile-up limit by at least an order of magnitude. The parameters are used to implement a low power miniaturised sensor in a 130 nm CMOS process, combining single photon detection, multiple channel timing and embedded pre-processing of the fluorescence lifetime, all within a silicon area of < 2 mm2. Single photon detection is achieved using an array of single photon avalanche diodes (SPADs) arranged in a digital silicon photomultiplier (SiPM) architecture with a 10 % fill-factor and a compressed 250 ps output pulse, which provides a photon throughput of > 700 MHz. An array of time-interleaved time-to-digital converters (TI-TDCs) with 50 ps resolution and no processing dead-time records up to eight photon events during each excitation period, significantly reducing the effect of TCSPC pile-up. The TCSPC data is then processed using an embedded centre-of-mass method (CMM) pre-calculation to produce single exponential fluorescence lifetime estimations in real-time. The combination of high photon throughput and real-time calculation enables advances in applications such as fluorescence lifetime imaging microscopy (FLIM) and time domain fluorescence lifetime activated cell sorting. To demonstrate this, the device is validated in practical bulk sample fluorescence lifetime, FLIM and simulated flow based experiments. Photon throughputs in excess of the excitation frequency are demonstrated for a range of organic and inorganic fluorophores for minimal error in lifetime calculation by CMM (< 5 %).
37

Second moments of incomplete Eisenstein series and applications

Yu, Shucheng January 2018 (has links)
Thesis advisor: Dubi Kelmer / We prove a second moment formula for incomplete Eisenstein series on the homogeneous space Γ\G with G the orientation preserving isometry group of the real (n + 1)-dimensional hyperbolic space and Γ⊂ G a non-uniform lattice. This result generalizes the classical Rogers' second moment formula for Siegel transform on the space of unimodular lattices. We give two applications of this moment formula. In Chapter 5 we prove a logarithm law for unipotent flows making cusp excursions in a non-compact finite-volume hyperbolic manifold. In Chapter 6 we study the counting problem counting the number of orbits of Γ-translates in an increasing family of generalized sectors in the light cone, and prove a power saving estimate for the error term for a generic Γ-translate with the exponent determined by the largest exceptional pole of corresponding Eisenstein series. When Γ is taken to be the lattice of integral points, we give applications to the primitive lattice points counting problem on the light cone for a generic unimodular lattice coming from SO₀(n+1,1)(ℤ\SO₀(n+1,1). / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Mathematics.
38

Preschool children's use of counting to compare two sets in cardinal situations

Zhou, Xin January 2001 (has links)
Thesis (Ed.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / This study investigated: 1) The effect of reminding or training on preschoolers' use of counting to compare two sets, and 2) the effect of test conditions on preschoolers' use of counting to compare two sets. Twelve comparison tasks (with sets: 4:5, 5:6, 6:7, and 8:9) were used to test 227 Chinese 3- and 4-year-olds' (ages ranged from 3:9 to 4: 11) use of counting to compare sets under different experimental conditions. Three test conditions, Control, Reminding of Counting, and Brief Training, were provided in Experiment 1. The Traditional and the Natural test condition were provided in Experiment 2. The intervention did not have an effect on younger children's (mean: 3:9) use of counting to compare sets. At the mean age of 4:4, the children were more likely to use counting to compare sets in the two intervention groups than were the children in the Control group. Children in the Natural test condition were more likely to use counting to compare sets than were the children in the Traditional test condition. A high percentage of Chinese 4-year-olds might already understand (or nearly) how to use counting to compare sets. Many 4-year-olds were reluctant to use counting if no intervention prompted it, because 1) they did not know that counting was a better strategy than visual comparison, or because 2) preschool children's use of counting to compare sets was easily affected by contextual factors in a test condition. Children were more likely to use counting to compare sets in a test condition in which familiar problem situations and concrete objects were used. Preschool children's use of counting to compare sets was found to be closely related to their counting performance, especially to their performance on the "Give a Number" task. / 2031-01-01
39

Automatic People Counting and Matching

Sallay, John 01 December 2009 (has links)
This thesis explores software algorithm for implementing a people counting and matching system to be used on a bus. A special camera is used, known as a texel camera, that generates depth and color information for a scene. This added information greatly facilitates both the tasks of matching and counting. Although people counting is a relatively mature field, there are several situations in which current technologies are not able to count correctly. Several of these difficult situations are tested with 82% counting accuracy. The idea of matching people on a bus is also developed. The goal is not to identify a specific person on a bus, but to find the time that a specific person is on the bus, and what bus stops were used. There are several aspects of this matching problem that differentiate it from other classification tasks that have been researched. In this thesis, multiple measurements are used to classify a person and sequence estimation techniques explored. The techniques developed classify with 92% accuracy, even with a relatively large number of people on a bus.
40

A Neural Model of Call-counting in Anurans

Houtman, David B. 11 October 2012 (has links)
Temporal features in the vocalizations of animals and insects play an important role in a diverse range of species-specific activities such as mate selection, territoriality, and hunting. The neural mechanisms underlying the response to such stimuli remain largely unknown. Two species of anuran amphibian provide a starting point for the investigation of the neurological response to species-specific advertisement calls. Neurons in the anuran midbrain of Rana pipiens and Hyla regilla exhibit an atypical response when presented with a fixed number of advertisement calls. The general response to these calls is mostly inhibitory; only when the correct number of calls is presented at the correct repetition rate will this inhibition be overcome and the neurons reach a spiking threshold. In addition to rate-dependent call-counting, these neurons are sensitive to missed calls: a pause of sufficient duration—the equivalent of two missed calls—effectively resets a neuron to its initial condition. These neurons thus provide a model system for investigating the neural mechanisms underlying call-counting and interval specificity in audition. We present a minimal computational model in which competition between finely-tuned excitatory and inhibitory synaptic currents, combined with a small propagation delay between the two, broadly explains the three key features observed: rate dependence, call counting, and resetting. While limitations in the available data prevent the determination of a single set of parameters, a detailed analysis indicates that these parameters should fall within a certain range of values. Furthermore, while network effects are counter-indicated by the data, the model suggests that recruitment of neurons plays a necessary role in facilitating the excitatory response of counting neurons—although this hypothesis remains untested. Despite these limitations, the model sheds light on the mechanisms underlying the biophysics of counting, and thus provides insight into the neuroethology of amphibians in general.

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