Time-resolved spectroscopy at surfaces and adsorbate dynamics: insights from a model-system approach

We introduce a model description of femtosecond laser induced desorption at surfaces. The substrate part of the system is taken into account as a (possibly semi-infinite) linear chain. Here, being especially interested in the early stages of dissociation, we consider a finite-size implementation of the model (i.e., a finite substrate), for which an exact numerical solution is possible. By time-evolving the many-body wave function, and also using results from a time-dependent density functional theory description for electron-nuclear systems, we analyze the competition between several surface-response mechanisms and electronic correlations in the transient and longer time dynamics under the influence of dipole-coupled fields. Our model allows us to explore how coherent multiple-pulse protocols can impact desorption in a variety of prototypical experiments.Comment: replaces a shorter versio

Two-loop Sunset Integrals at Finite Volume

We show how to compute the two-loop sunset integrals at finite volume, for non-degenerate masses and non-zero momentum. We present results for all integrals that appear in the Chiral Perturbation Therory ($\chi$PT) calculation of the pseudoscalar meson masses and decay constants at NNLO, including the case of Partially Quenched $\chi$PT. We also provide numerical implementations of the finite-volume sunset integrals, and review the results for one-loop integrals at finite volume.Comment: 45 page

Density Functional Theory of the Hubbard-Holstein Model

We present a density functional theory (DFT) for lattice models with local electron-electron (e-e) and electron-phonon (e-ph) interactions. Exchange-correlation potentials are derived via dynamical mean field theory for the infinite-dimensional Bethe lattice, and analytically for an isolated Hubbard-Holstein site. These potentials exhibit discontinuities as a function of the density, which depend on the relative strength of the e-e and e-ph interactions. By comparing to exact benchmarks, we show that the DFT formalism gives a good description of the linear conductance and real-time dynamics.Comment: 5 pages, 3 figures, supplemental material provided as pd

Elämänhallintaa tukeva vertaisryhmä muistisairaiden omaishoitajille : yhdessä kehitetty toteutussuunnitelma

Opinnäytetyön tarkoituksena oli selvittää omaishoitajien odotukset ja toiveet vertaisryhmälle sekä heitä omassa arjessaan voimaannuttavia seikkoja. Tavoitteena oli kehittää toteutussuunnitelma voimaannuttavalle omaishoitajien vertaisryhmälle, joka aloittaa toimintansa Taavin muistipalvelukeskuksessa. Espoon muistipalvelukeskukset tarjoavat hoiva-asumista muistisairaille ja palveluja kotona asumisen tueksi. Opinnäytetyö toteutettiin yhteistyössä Espoon kaupungin pitkäaikaishoidon kanssa. Opinnäytetyö toteutettiin laadullisena tutkimuksena. Aineistonkeruumenetelmänä käytettiin yhteiskehittelyä, johon valittiin voimavaralähtöinen näkökulma. Yhteiskehittelyllä mahdollistettiin omaishoitajien osallisuus jo vertaisryhmän suunnitteluvaiheessa. Tapaamisia järjestettiin kaksi ja niihin osallistui kuusi omaishoitajaa sekä yksi Taavin muistipalvelukeskuksen työntekijä. Tapaamisissa tuotettu aineisto analysoitiin aineistolähtöisellä sisällönanalyysillä. Tulosten mukaan omaishoitajien voimavarana on yhteinen elämä puolisoidensa kanssa, jota he haluavat jatkaa puolison sairastumisesta huolimatta. Arkea ja jaksamista tukevat harrastukset, vapaa-aika, vertaisuus sekä tiedollinen tuki. Elämänhallintaa ja voimaantumista voidaan tulosten mukaan tukea vertaisryhmässä. Tämä onnistuu tukemalla omaishoitajien omia voimavaroja sekä arjessa jaksamista vertaisuuden ja tiedollisen tuen avulla. Osallistumisen mahdollistuminen on edellytys vertaisryhmästä saatavalle tuelle. Tulosten perusteella voi todeta, että omaishoitajat eivät suinkaan koe saavansa tarvitsemaansa tietoa ja tukea riittävästi, vaikka tähän elämäntilanteeseen liittyvä tiedon tarve on tulosten mukaan suuri. Eräs ratkaisu tähän on omaishoitajille alkuvaiheessa suunnattu koulutus, joka pitää sisällään tietoa niin sairauteen kuin tukimuotoihin liittyvistä seikoista. Tällöin vertaisryhmässä voitaisiin keskittyä suuresti kaivattuun keskusteluun ja kokemusten jakamiseen. Opinnäytetyö käsittelee jo kunnallisen omaishoidon palvelujen piirissä olevia omaishoitajia, mutta voidaan arvioida, että tiedon ja tuen tarve koskettaa eritoten heitä, jotka jäävät näiden palvelujen ulkopuolelle.The purpose of this thesis was to clarify expectations and wishes that caregivers have for a peer group and also to clarify empowering elements in their everyday life. The target was to develop a scheme for an empowering peer group for caregivers initiating in Taavi Memory Service Centre. The Memory Service Centre offers care housing for people with memory disorders and services to support living at home. This thesis was carried out in cooperation with long-term care in the city of Espoo. This thesis was carried out as a qualitative research. Data for this study were collected in two sessions using co-creation. A resource-centered approach in co-creation enabled the participation of caregivers in early planning of the peer group. In total, six caregivers and one Taavi Memory Service Centre employee participated in these sessions. The data was analyzed by using a data-oriented content analysis. The results showed that sharing lives with their spouses is a resource for caregivers and they are willing to continue their lives together despite memory disease. Hobbies, leisure, peer and cognitive support are the elements which support coping in everyday life. Promoting sense of coherence and empowerment is possible in the peer group. This can be done by supporting caregivers’ own empowering elements and managing their everyday life by peer and cognitive support. However, this requires an opportunity of attendance at the peer group. The results lead to the conclusion that caregivers do not experience getting enough such information and support they need, even though the demand for information related to their life situation is great. One solution solving the lack of information and support is training for caregivers in the early-stage of disease, including information on memory disorder and support. This enables focusing on the long-awaited conversations and sharing experiences in the peer group. This thesis examines the needs of those caregivers who are already getting caregiver’s allowance and services, but it can be assumed that especially those caregivers, who are not getting the allowance, are in need for support

Nonequilibrium Green's functions and atom-surface dynamics: Simple views from a simple model system

We employ Non-equilibrium Green's functions (NEGF) to describe the real-time dynamics of an adsorbate-surface model system exposed to ultrafast laser pulses. For a finite number of electronic orbitals, the system is solved exactly and within different levels of approximation. Specifically i) the full exact quantum mechanical solution for electron and nuclear degrees of freedom is used to benchmark ii) the Ehrenfest approximation (EA) for the nuclei, with the electron dynamics still treated exactly. Then, using the EA, electronic correlations are treated with NEGF within iii) 2nd Born and with iv) a recently introduced hybrid scheme, which mixes 2nd Born self-energies with non-perturbative, local exchange-correlation potentials of Density Functional Theory (DFT). Finally, the effect of a semi-infinite substrate is considered: we observe that a macroscopic number of de-excitation channels can hinder desorption. While very preliminary in character and based on a simple and rather specific model system, our results clearly illustrate the large potential of NEGF to investigate atomic desorption, and more generally, the non equilibrium dynamics of material surfaces subject to ultrafast laser fields.Comment: 10 pages, 5 figure

Non-Perturbative Theory for Dispersion Self-Energy of Atoms

We go beyond the approximate series-expansions used in the dispersion theory of finite size atoms. We demonstrate that a correct, and non-perturbative, theory dramatically alters the dispersion selfenergies of atoms. The non-perturbed theory gives as much as 100% corrections compared to the traditional series expanded theory for the smaller noble gas atoms.Comment: 3 pages, no figures, 1 tabl

Lithium atom storage in nanoporous cellulose via surface induced Li2\rm Li_2 breakage

We demonstrate a physical mechanism that enhances a splitting of diatomic $\rm Li_2$ at cellulose surfaces. The origin of this splitting is a possible surface induced diatomic excited state resonance repulsion. The atomic Li is then free to form either physical or chemical bonds with the cellulose surface and even diffuse into the cellulose layer structure. This allows for an enhanced storage capacity of atomic Li in nanoporous celluloseComment: 5 pages, 6 figure