Abductive, Causal, and Counterfactual Conditionals Under Incomplete Probabilistic Knowledge

We study abductive, causal, and non-causal conditionals in indicative and counterfactual formulations using probabilistic truth table tasks under incomplete probabilistic knowledge (N = 80). We frame the task as a probability-logical inference problem. The most frequently observed response type across all conditions was a class of conditional event interpretations of conditionals; it was followed by conjunction interpretations. An interesting minority of participants neglected some of the relevant imprecision involved in the premises when inferring lower or upper probability bounds on the target conditional/counterfactual ("halfway responses"). We discuss the results in the light of coherence-based probability logic and the new paradigm psychology of reasoning.Comment: typos correcte

Mass-polariton theory of light in dispersive media

We have recently shown that the electromagnetic field in a medium is made of mass-polariton (MP) quasiparticles, which are quantized coupled states of the field and an atomic mass density wave (MDW) [Phys. Rev. A 95, 063850 (2017)]. In this work, we generalize the MP theory of light for dispersive media assuming that absorption and scattering losses are very small. Following our previous work, we present two different approaches to the theory of light: (1) the MP quasiparticle theory, which is derived by only using the fundamental conservation laws and the Lorentz transformation; (2) the classical optoelastic continuum dynamics (OCD), which is a generalization of the electrodynamics of continuous media to include the dynamics of the medium under the influence of optical forces. For the coupled MP state of a single photon and the medium, we obtain the total MP momentum of the Minkowski form while the field's share of the momentum is equal to the Abraham momentum. We also show that the correspondence between the MP and OCD models and the conservation of momentum at interfaces gives an unambiguous formula for the optical force. The dynamics of the light pulse and the related MDW lead to nonequilibrium of the medium and to relaxation of the atomic density by sound waves in the same way as for nondispersive media. We also carry out simulations for optimal measurements of atomic displacements related to the MDW in silicon. In the simulations, we consider different waveguide cross-sections and optical pulse widths and account for the breakdown threshold irradiance of materials. We also compare the MP theory to previous theories of the momentum of light in a dispersive medium. We show that our generalized MP theory resolves all the problems related to the Abraham-Minkowski dilemma in a dispersive medium

Nonequilibrium phonon mean free paths in anharmonic chains

Harnessing the power of low-dimensional materials in thermal applications calls for a solid understanding of the anomalous thermal properties of such systems. We analyze thermal conduction in one-dimensional systems by determining the frequency-dependent phonon mean free paths (MFPs) for an anharmonic chain, delivering insight into the diverging thermal conductivity observed in computer simulations. In our approach, the MFPs are extracted from the length-dependence of the spectral heat current obtained from nonequilibrium molecular dynamics simulations. At low frequencies, the results reveal a power-law dependence of the MFPs on frequency, in agreement with the diverging conductivity and the recently determined equilibrium MFPs. At higher frequencies, however, the nonequilibrium MFPs consistently exceed the equilibrium MFPs, highlighting the differences between the two quantities. Exerting pressure on the chain is shown to suppress the mean free paths and to generate a weaker divergence of MFPs at low frequencies. The results deliver important insight into anomalous thermal conduction in low-dimensional systems and also reveal differences between the MFPs obtained from equilibrium and nonequilibrium simulations.Comment: 8 pages, 7 figures, minor changes to v

Thermal balance and photon-number quantization in layered structures

The quantization of the electromagnetic field in lossy and dispersive dielectric media has been widely studied during the last few decades. However, several aspects of energy transfer and its relation to consistently defining position-dependent ladder operators for the electromagnetic field in nonequilibrium conditions have partly escaped the attention. In this work we define the position-dependent ladder operators and an effective local photon-number operator that are consistent with the canonical commutation relations and use these concepts to describe the energy transfer and thermal balance in layered geometries. This approach results in a position-dependent photon-number concept that is simple and consistent with classical energy conservation arguments. The operators are formed by first calculating the vector potential operator using Green's function formalism and Langevin noise source operators related to the medium and its temperature, and then defining the corresponding position-dependent annihilation operator that is required to satisfy the canonical commutation relations in arbitrary geometry. Our results suggest that the effective photon number associated with the electric field is generally position dependent and enables a straightforward method to calculate the energy transfer rate between the field and the local medium. In particular, our results predict that the effective photon number in a vacuum cavity formed between two lossy material layers can oscillate as a function of the position suggesting that also the local field temperature oscillates. These oscillations are expected to be directly observable using relatively straightforward experimental setups in which the field-matter interaction is dominated by the coupling to the electric field

Role of anharmonic phonon scattering in the spectrally decomposed thermal conductance at planar interfaces

Detailed understanding of vibrational heat transfer mechanisms between solids is essential for the efficient thermal engineering and control of nanomaterials. We investigate the frequency dependence of anharmonic scattering and interfacial thermal conduction between two acoustically mismatched solids in planar contact by calculating the spectral decomposition of the heat current flowing through an interface between two materials. The calculations are based on analyzing the correlations of atomic vibrations using the data extracted from non-equilibrium molecular dynamics simulations. Inelastic effects arising from anharmonic interactions are shown to significantly facilitate heat transfer between two mass-mismatched face-centered cubic lattices even at frequencies exceeding the cut-off frequency of the heavier material due to (i) enhanced dissipation of evanescent vibrational modes and (ii) frequency-doubling and frequency-halving three-phonon energy transfer processes at the interface. The results provide substantial insight into interfacial energy transfer mechanisms especially at high temperatures, where inelastic effects become important and other computational methods are ineffective.Comment: minor changes to v

Noiseless amplification of weak coherent fields without external energy

According to the fundamental laws of quantum optics, noise is necessarily added to the system when one tries to clone or amplify a quantum state. However, it has recently been shown that the quantum noise related to the operation of a linear phase-insensitive amplifier can be avoided when the requirement of a deterministic operation is relaxed. Nondeterministic noiseless linear amplifiers are therefore realizable. Usually nondeterministic amplifiers rely on using single photon sources. We have, in contrast, recently proposed an amplification scheme in which no external energy is added to the signal, but the energy required to amplify the signal originates from the stochastic fluctuations in the field itself. Applying our amplification scheme, we examine the amplifier gain and the success rate as well as the properties of the output states after successful and failed amplification processes. We also optimize the setup to find the maximum success rates in terms of the reflectivities of the beam splitters used in the setup. In addition, we discuss the nonidealities related to the operation of our setup and the relation of our setup with the previous setups.Comment: arXiv admin note: substantial text overlap with arXiv:1309.428

Monte Carlo study of non-quasiequilibrium carrier dynamics in III–N LEDs

Hot carrier effects have been observed in recent measurements of III–Nitride (III–N) light-emitting diodes. In this paper we carry out bipolar Monte Carlo simulations for electrons and holes in a typical III–N multi-quantum well (MQW) LED. According to our simulations, significant non-quasiequilibrium carrier distributions exist in the barrier layers of the structure. This is observed as average carrier energies much larger than the 1.5kBT1.5kBT corresponding to quasi-equilibrium. Due to the small potential drop over the MQW being modest, the non-quasiequilibrium carriers can be predominantly ascribed to nnp and npp Auger processes taking place in the QWs. Further investigations are needed to determine the effects of hot carriers on the macroscopic device characteristics of real devices

Generalized noise terms for the quantized fluctuational electrodynamics

The quantization of optical fields in vacuum has been known for decades, but extending the field quantization to lossy and dispersive media in nonequilibrium conditions has proven to be complicated due to the position-dependent electric and magnetic responses of the media. In fact, consistent position-dependent quantum models for the photon number in resonant structures have only been formulated very recently and only for dielectric media. Here we present a general position-dependent quantized fluctuational electrodynamics (QFED) formalism that extends the consistent field quantization to describe the photon number also in the presence of magnetic field-matter interactions. It is shown that the magnetic fluctuations provide an additional degree of freedom in media where the magnetic coupling to the field is prominent. Therefore, the field quantization requires an additional independent noise operator that is commuting with the conventional bosonic noise operator describing the polarization current fluctuations in dielectric media. In addition to allowing the detailed description of field fluctuations, our methods provide practical tools for modeling optical energy transfer and the formation of thermal balance in general dielectric and magnetic nanodevices. We use the QFED to investigate the magnetic properties of microcavity systems to demonstrate an example geometry in which it is possible to probe fields arising from the electric and magnetic source terms. We show that, as a consequence of the magnetic Purcell effect, the tuning of the position of an emitter layer placed inside a vacuum cavity can make the emissivity of a magnetic emitter to exceed the emissivity of a corresponding electric emitter

Ruotsin populistipuolueiden maahanmuuttoretoriikka 1990-luvulla.

Only abstract. Paper copies of master’s theses are listed in the Helka database (http://www.helsinki.fi/helka). Electronic copies of master’s theses are either available as open access or only on thesis terminals in the Helsinki University Library.Vain tiivistelmä. Sidottujen gradujen saatavuuden voit tarkistaa Helka-tietokannasta (http://www.helsinki.fi/helka). Digitaaliset gradut voivat olla luettavissa avoimesti verkossa tai rajoitetusti kirjaston opinnäytekioskeilla.Endast sammandrag. Inbundna avhandlingar kan sökas i Helka-databasen (http://www.helsinki.fi/helka). Elektroniska kopior av avhandlingar finns antingen öppet på nätet eller endast tillgängliga i bibliotekets avhandlingsterminaler.Länsi-Eurooppa koki voimakaan taloudellisen kasvun toisen maailmansodan jälkeen. Talouskasvun seurauksena Länsi-Eurooppa veti puoleensa maahanmuuttajia. Taloudellisesti heikot ajat ja etenkin ensimmäinen öljykriisi kuitenkin muuttivat tilannetta ja maahanmuuttoa alettiin rajoittaa Länsi-Euroopassa. 1980-luvulla turvapaikanhakijat muodostivat entistä suuremman osan maahanmuuttajista. 1970-luvulta lähtien eurooppalaiset maahanmuuttovastaiset puolueet onnistuivat keräämään merkittävää kannatusta. Ruotsissa maahanmuuttovastaiset puolueet eivät kuitenkaan onnistuneet keräämään merkittävää menestystä ennen vuotta 1991, kun Ny demokrati -puolue nousi Ruotsin valtiopäiville. Lisäksi 1990-luvulla Sverigedemokraterna -puolue onnistui kasvattamaan kannatustaan. Tutkielmassa tarkastellaan kyseisten puolueiden maahanmuuttoretoriikkaa 1990-luvulla ja sitä, miten kyseiset puolueet käyttivät maahanmuuttajia retoriikassaan ja politiikassaan. Tutkielmassa pyritään myös selvittämään, olivatko tutkitut puolueet ns. "yhden asian puolueita", eli keskittyivätkö puolueet ainoastaan maahanmuuton vastustamiseen. Tutkielmassa tarkastellaan puolueiden maahanmuuttoretoriikkaa suhteessa talouteen, yhteiskuntaan, kulttuuriin ja kehitysapuun. Tutkielma on kvalitatiivinen ja pääasiallisena lähdeaineistoina on käytetty puolueiden puolueohjelmia. Lisäksi tutkielmaa varten on luettu kolmea sanomalehteä: Svenska Dagbladet, Sydsvenskan Dagbladet ja Dagens Nyheter. Johtopäätöksenä todetaan, että tutkitut puolueet olivat omaksuneet etnonationalistisen ideologian, johon kuuluu ajatus yhtenäisestä ”kansasta”, joka on myös ”etnisesti” yhteneväinen. Vuonna 1991 perustettu Ny demokrati ei ollut aluksi rasistinen puolue, vaan uusliberalistinen puolue, joka oli lähinnä keskittynyt talouspolitiikkaan. Sisäisten ristiriitojen ja huonon vaalimenestyksen seurauksena puolue päätyi kansallismielisten jäseniensä käsiin ja puolueen politiikka sekä retoriikka muuntuivat kansallismieliseksi. Hiljalleen puolueesta kehittyi rasistinen puolue. Sverigedemokraterna -puolue on ollut perustamisestaan asti kansallismielinen puolue, joka on suhtautunut avoimen vihamielisesti maahanmuuttoon ja maahanmuuttajiin. Sverigedemokraterna -puolue oli mm. halukas karkottamaan "etnisesti vieraat" ihmiset Ruotsista. Sverigedemokraterna -puolue on myös pyrkinyt esiintymään sosiaalidemokraattisen tradition jatkajana ja kansankodin puolustajana. Tutkittujen puolueiden näkemyksiä maahanmuutosta voidaan kuvailla kielteiseksi. Tutkitut puolueet esittivät maahanmuuttajat henkisesti epäkypsinä henkilöinä, jotka eivät pystyneet huolehtimaan taloudestaan. Maahanmuuttajien katsottiin olevan epäaktiivisia ihmisiä, jotka eivät olleet halukkaita oppimaan ruotsin kieltä. Tutkitut puolueet toivat retoriikassaan esille, että maahanmuuttajat ja heidän kulttuurinsa koettiin uhkana ruotsalaiselle kulttuurille ja yhteiskunnalle. Puolueiden mukaan oli vaara, että Ruotsissa syntyisi avoin konflikti maahanmuuton seurauksena