Cortical representations for phonological quantity

Different languages use temporal speech cues in different linguistic functions. In Finnish, speech-sound duration is used as the primary cue for the phonological quantity distinction ― i.e., a distinction between short and long phonemes. For the second-language (L2) learners of Finnish, quantity is often difficult to master if speech-sound duration plays a less important role in the phonology of their native language (L1). The present studies aimed to investigate the cortical representations for phonological quantity in native speakers and L2 users of Finnish by using behavioral and electrophysiological methods. Since long-term memory representations for different speech units have been previously shown to participate in the elicitation of the mismatch negativity (MMN) brain response, MMN was used to compare the neural representation for quantity between native speakers and L2 users of Finnish. The results of the studies suggested that native Finnish speakers' MMN response to quantity was determined by the activation of native-language phonetic prototypes rather than by phoneme boundaries. In addition, native speakers seemed to process phoneme quantity and quality independently from each other by separate brain representations. The cross-linguistic MMN studies revealed that, in native speakers of Finnish, the MMN response to duration or quantity-degree changes was enhanced in amplitude selectively in speech sounds, whereas this pattern was not observed in L2 users. Native speakers' MMN enhancement is suggested to be due to the pre-attentive activation of L1 prototypes for quantity. In L2 users, the activation of L2 prototypes or other L2 learning effects were not reflected in the MMN, with one exception. Even though L2 users failed to show native-like brain responses to duration changes in a vowel that was similar in L1 and L2, their duration MMN response was native-like for an L2 vowel with no counterpart in L1. Thus, the pre-attentive activation of L2 users' representations was determined by the degree of similarity of L2 sounds to L1 sounds. In addition, behavioral experiments suggested that the establishment of representations for L2 quantity may require several years of language exposure.Eri kielet käyttävät äänteiden kestovihjeitä erilaisissa kielellisissä tehtävissä. Suomessa äänteen kesto on kvantiteetin eli lyhyiden ja pitkien foneemien erottamisen tärkein vihje. Suomea toisena kielenä puhuvien on usein vaikea oppia kvantiteetti, jos äänteen kestolla on vähäisempi merkitys heidän äidinkielessään. Tämän väitöskirjan tutkimuksissa tarkasteltiin aivovastemittausten ja foneettisten testien avulla kvantiteettikategorioiden muistijälkiä äidinkieleltään suomenkielisten ja suomea toisena kielenä puhuvien aivokuorella. Koska äänteiden pitkäkestoisten muistijälkien on aiemmin todettu osallistuvan MMN-aivovasteen (engl. mismatch negativity) syntymiseen, sitä käytettiin selvittämään, miten äidinkieleltään suomenkielisten ja suomea toisena kielenä puhvien kvantiteettikategorioiden muistijäljet poikkeavat toisistaan. Tulosten mukaan äidinkieleltään suomenkielisten MMN-vasteen voimakkuus määräytyi äidinkielen foneettisten prototyyppien mukaan eikä foneemien rajojen mukaan. Lisäksi suomenkieliset näyttivät käsittelevän foneemin laadun ja kvantiteetin toisistaan riippumattomasti, eri kategorioiden kautta. Kieliryhmiä vertailevat MMN-tutkimukset puolestaan osoittivat, että äidinkieleltään suomenkielisillä MMN-vaste keston muutokselle oli nimenomaan puheäänteiden kohdalla voimakkaampi kuin toisen kielen oppijoilla. Tämä saattaa johtua foneettisten prototyyppien esitietoisesta aktivoitumisesta äidinkieleltään suomenkielisten aivokuorella. Toisen kielen oppijoilla toisen kielen prototyyppien aktivoituminen tai kielenoppiminen ylipäänsä eivät näkyneet MMN-vasteessa yhtä poikkeusta lukuun ottamatta. Vaikka suomea toisena kielenä puhuvien aivovasteiden voimakkuus äänteen keston muutokselle ei saavuttanut äidinkielisten tasoa vokaalissa, joka oli samankaltainen heidän äidinkielessään ja toisessa kielessään, he saavuttivat suomenkielisten tason vokaalissa, jolla ei ollut vastinetta heidän äidinkielessään. Näin ollen äidinkielen ja toisen kielen äänteiden samankaltaisuus näyttäisi vaikuttavan suomea toisena kielenä puhuvien muistijälkien esitietoiseen aktivoitumiseen. Tutkimuksen foneettisten kokeiden mukaan kategorioiden syntyminen toisen kielen kvantiteetille saattaa vaatia useiden vuosien altistusta toiselle kielelle

Restriction of Powers : Human Rights Protection in the context of Security Council

Is about the sanctions and procedures of the United Nations Security Council and the problems their application in practise may cause. Two cases are presented to exemplify the problems from an individual’s standpoint as well as that of the states bound by obligations towards individuals. The Kadi case represents a very direct breach of the rights of individuals attempted to justify with the need to protect and maintain international peace and security. It is argued that principles of necessity, proportionality, due process and legality are not paid sufficient attention and that the sanctions imposed by the Security Council should not be targeted on individuals since adequate means for legal protection are not available against such sanctions dictated by an intra-governmental organ without the capacity to arrange court hearings should the targeted individual wish to defend their self against the accusations. The facts of the Kadi case are presented along with the assessment of the human rights that conflict with the Security Council Resolutions in question. The improvements made into the procedures of the Sanctions Committee are noted despite the conclusion that they are not sufficient to make up for the inherent deficiencies of the sanctioning system in terms of human rights guarantees. In the Lockerbie case, the thesis argues, the Security Council was utilized to circumvent an international treaty to allow for a result that satisfied two of the permanent members of the Council, which again led to a violation of the rights of an individual. The Security Council demanded Libya to adjust its claims under the Montreal Convention which essentially prevented the International Court of Justice from effectively applying its jurisdiction. Instead being given the opportunity to trial its own nationals, Libya was pressured into allowing an international ad hoc court to try the suspects in the Netherlands. As a result, the individuals in question were put through a trial in which their rights as the accused where blatantly overlooked. Whether the convicted individual or any Libyan national for that matter, was responsible for the bomb aboard the Pan Am flight that exploded above Lockerbie in 1988 Is left uncertain. The authority and function of the Security Council and the historical background of it is presented in the third chapter. The reality of international politics is taken into account when deliberating the options for the restriction of the actions of the Council. The instances that are examined in sought of possible solutions include the International Court of Justice, the United Nations Charter, the General Assembly, human rights and international law. Assessment of the possible restrictions is performed taking into consideration the continuing need for an effective organ with the means to intervene when something threatens international peace or security. The credibility of the institution and the present and (possible) future compliance issues are reflected on. The European development in especially the field of human rights protection is presented as a possible source of inspiration for improving respect for fundamental human rights within the United Nations. The conclusions present the need to balance the different goals of the international community and the Security Council as the instrument of international law enforcement. Effective peace maintenance and human rights protection need to find correspondence with the interests of both the members of the Security Council and the general membership of the United Nations to allow both individual and common benefits realized. Being aware of the difficulties in changing greatly influential, international documents such as the United Nations Charter, which was obviously a result of various compromises to begin with, changing the Charter directly, is mostly disregarded as an option for updating the function of the Security Council. The thesis relies on the assumption that changing the Charter is not a realistic option at the moment and looks for solutions to the presented problems elsewhere. Gradually changing the present standpoints, deliberation procedures could amount to a sufficient correction of the power locus around the Security Council. If not, the International Court of Justice adopting a more teleological style of interpretation to reign in the actions of the Council could pose as a last resort to finding the necessary check to the balances

Inverse Problems and Dynamical Systems in Tomography and Optics

The dissertation concerns inverse problems and dynamical systems. Inverse problems, as a subfield of mathematics, studies the mathematical theory of indirect measurements. It is an active area of research with extensive mathematical theory and numerous applications. Many inverse problems are concerned with physical systems that evolve in time. A mathematical model that describes how a quantity evolves in time is called a dynamical system. X-ray computed tomography is a technique where the inner structure of an object is computed from a number of its X-ray images. In the first publication of the dissertation we consider X-ray computed tomography in a setting where the orientations in which the object was imaged are unknown. This problem is called tomography with unknown view angles; such a problem arises e.g. in cryogenic electron microscopy of viral particles. We show that under general assumptions it is possible to reconstruct the structure of the object in tomography with unknown view angles. Diffusion is the flow of a substance from areas of high concentration to areas of low concentration. In the second publication we consider an inverse problem for the space–time fractional diffusion equation. This equation models diffusion and anomalous diffusion processes, such as those sometimes observed in fractured geological formations. We show that the geometry of the underlying space can be determined by observing the evolution of a solution of the equation in a subset of the space. In the third and fourth publications we consider a dynamical system that models injection locking in a laser. Injection locking is a technique where light from one laser is injected into another laser's cavity (the part of a laser where the emitted light is created) with the intention of altering the laser's properties. The idea is to consider injection locking as a process that can provide the basis for optical computing devices. In the third publication we derive an approximation for the nonlinear relationship between the injected light and the injection-locked emitted light, and we show that it is possible to construct an optical logic gate based on this relationship. In the fourth publication we do a detailed analysis of the dynamical system that models injection locking in lasers, and based on this analysis, we propose a design for an optical neural network.Väitöskirja käsittelee käänteisten ongelmien ja dynaamisten järjestelmien matemaattista teoriaa. Käänteisissä ongelmissa pyritään ymmärtämään ilmiön syy sen seurauksia. Esimerkki käänteisestä ongelmasta on röntgenkuvaus, jossa kappaleen läpäisseiden säteiden vaimenemisesta (seuraus) halutaan päätellä vaimenemisen syy (kappaleen sisäinen rakenne). Usein käänteisen ongelman liittyvä tarkasteltava suure on dynaaminen, eli se muuttuu ajan mukana. Tällaisen ilmiön matemaattista mallia kutsutaan dynaamiseksi järjestelmäksi. Väitöskirjan ensimmäisessä julkaisussa tutkitaan tietokonekerroskuvauksen matemaattista teoriaa. Tietokonekerroskuvauksessa tarkasteltavasta kohteesta kuvataan röntgenkuvia useista eri suunnista, ja näistä kuvista pyritään laskemaan kohteen sisäinen rakenne. Usein suunnat joista kuvat on otettu tunnetaan, mutta tietyissä tilanteissa nämä kuvaussuunnat ovat tuntemattomia. Tällainen tilanne on esimerkiksi virusten kuvantamisessa käytetyssä kryogeenisessa elektronimikroskopiassa. Julkaisussa osoitetaan, että kohteen rakenteen määrittäminen on yleensä mahdollista vaikka kuvaussuunnat olisivatkin tuntemattomia. Lämmön johtumisen matemaattista mallia kutsutaan lämpöyhtälöksi. Lämmön johtuminen aineen sisällä riippuu sekä aineen kyvystä johtaa lämpöä (ns. lämmönjohtavuuskertoimesta), että tarkasteltavan kappaleen muodosta. Väitöskirjan toisessa julkaisussa tutkitaan käänteistä ongelmaa lämpöyhtälölle. Julkaisussa osoitetaan, että tarkastelemalla kappaleen lämpötilan käyttäytymistä osassa kappaletta voidaan päätellä sekä koko kappaleen muoto, että sen lämmönjohtavuuskerroin. Kolmannessa ja neljännessä julkaisussa tutkitaan optiseen laskentaan liittyvän dynaamisen järjestelmän matemaattista teoriaa. Nykyisten puolijohdekomponentteihin perustuvien tietokoneiden toiminta perustuu sähköön, optisessa laskennassa tavoite on rakentaa tietokone jonka toiminta perustuu sähkön sijaan valoon. Julkaisuissa tutkitaan lasereiden synkronoitumiseen liittyvän ilmiön (ns. injektiolukituksen) matemaattisia ominaisuuksia. Julkaisuissa osoitetaan että ominaisuuksiensa puolesta injektiolukitusta voi olla mahdollista hyödyntää optisten transistoreiden tai optisten neuroverkkojen rakentamisessa

The effect on learning of paired traditional students in a lab setting

Includes bibliographical references

New silicon photonics integration platform enabled by novel micron-scale bends

Even though submicron silicon waveguides have been proposed for dense integration of photonic devices, to date the lightwave circuits on the market mainly rely on waveguides with micron-scale core dimensions. These larger waveguides feature easier fabrication, higher reliability and better interfacing to optical fibres. Single-mode operation with large core dimensions is obtained with low lateral refractive index contrast. Hence, the main limitation in increasing the level of integration and in reducing the cost of micron-scale waveguide circuits is their mm- to cm-scale minimum bending radius. Fortunately, single-mode rib waveguides with a micron-scale silicon core can be locally transformed into multi-mode strip waveguides that have very high lateral index contrast. Here we show how Euler spiral bends realized with these waveguides can have bending radii below 10 {\mu}m and losses below 0.02 dB/90{\deg} for the fundamental mode, paving way for a novel densely integrated platform based on micron-scale waveguides.Comment: 14 pages, 29 Refs., 5 Fig