Journal Staff

Idag är det inte bara genom traditionella utbildningar som värdefulla förmågor kan erhållas, utan detta kan även ske genom internet, samt på andra fysiska platser utanför skolan. Dessvärre finns det inte något allmänt accepterat sätt att redovisa denna informella kompetens. För att lösa detta problem har den amerikanska stiftelsen Mozilla Foundation, känd för att ha utvecklat webbläsaren “Mozilla Firefox”, skapat “Open Badges”. Open Badges är en typ av e-utmärkelse, dvs. ett digitalt certifikat, som till skillnad från andra innehåller metadata som gör det möjligt att verifiera vem som är utgivaren, vad som krävdes för att skaffa och vem badgen är utgiven till m.m.   Genom denna uppsats ämnar vi ta reda på om och i sådana fall varför denna typ av belöning motiverar studenter att slutföra en onlinekurs om miljömedvetenhet. För att undersöka detta skapades en hemsida och en kurs med en uppdragsbaserad struktur. Två olika grupper med tio personer vardera erbjöds genomföra kursen. Den ena gruppen informerades om hur Open Badges fungerar och att de skulle belönas med en sådan om de slutförde kursen (“Open Badges-gruppen”). Den andra gruppen fick inte denna information (“kontrollgruppen”). Efter kursomgångens slut kallades de medverkande till en fokusgrupp för att diskutera Open Badges.   Vi fann att i den grupp som informerades om Open Badges slutförde två av tio kursen medan noll av tio i kontrollgruppen slutförde kursen. I fokusgruppen förklarade de två som slutförde kursen att det var specifikt deras önskan att få en Open Badge som motiverade dem att utföra de uppdrag de tyckte var jobbiga. Samtliga personer i fokusgruppen tyckte även att framtiden för Open Badges beror på arbetsgivares användning av dem.   Eftersom det bara var personer i Open Badges-gruppen som slutförde hela kursen tyder detta på att Open Badges fungerar bra som motivationskälla. Detta styrks även av att studenterna i fokusgruppen slutförde vissa uppdrag eftersom de blev motiverade av Open Badgen, även om de tyckte dessa uppdrag var svåra eller jobbiga.   De deltagare som genomförde kursen ansåg att Open Badges gav motivation för att det kändes som ett slutmål. De ansåg även att det var spännande och intressant och såg även en potential i Open Badges i allmänhet, inte endast för den badge vi utdelade, som merit på arbetsmarknaden.   Alla deltagare såg användningsområden för Open Badges både online (utanför traditionella utbildningsinstitut) och offline (vid traditionella utbildningsinstitut). De tyckte att Open Badges kunde användas online för att visa på att man lärt sig något på egen hand, och offline för att belöna exemplariskt arbete, till exempel en Badge för bästa kursresultat i någon speciell kurs.Today it is not only through traditional education that skills can be acquired. Skills can also be gained through the internet as well as at physical locations other than academic institutions. However there is currently no universally accepted way to display this informal knowledge. To solve this problem the American organization Mozilla Foundation, who created the web browser “Mozilla Firefox”, has created “Open Badges”. An Open Badge is a type of achievement that, in contrast to other achievements, contains metadata which enables verification of the issuer, the steps needed to receive the Badge and information about who received the badge etc.   Through this essay we intend to find out if and why this kind of reward motivates students to complete an online course about environmental awareness. To investigate this we created a homepage containing an online course with a mission based structure. Two different groups with ten members each had the choice to complete the course. In one of the groups the participants were informed about Open Badges and how it works (the “Open Badges group”). The participants in the other group did not get this information (the “control group”). After the online course’s deadline was due we held a focus group meeting to discuss Open Badges.   We found that in the Open Badges group two out of ten students completed the course. Zero out of ten students in the control group completed the course. At the focus group meeting the two students who completed the course explained that Open Badges explicitly motivated them to complete the missions in the online course which they thought were strenuous. All of the students in the focus group argued that for Open Badges to work, it needs to be adopted by the labor market.   Since the students who completed the course were in the Open Badges-group, the results lean toward showing that Open Badges in fact work as a motivational source. This claim is also supported by the fact that the students in the focus group completed some missions just because they were motivated by the Open Badge, even though they considered these missions hard or strenuous.   The participants who completed the course believed Open Badges gave them motivation because it felt like a final goal. They also thought it was exciting and interesting. Additionally, they saw potential in Open Badges in general, not only for the Badge they received, as a merit on the labor market. All participants saw ways of using Open Badges both online (outside of traditional educational institutions) and offline (at traditional educational institutions). They thought that Open Badges could be used online in order to show what you have learned on your own, and offline to reward exemplary work, for example a Badge for the best course result in a specific course

Study of attosecond delays using perturbation diagrams and exterior complex scaling

We describe in detail how attosecond delays in laser-assisted photoionization can be computed using perturbation theory based on two-photon matrix elements. Special emphasis is laid on above-threshold ionization, where the electron interacts with an infrared field after photoionization by an extreme ultraviolet field. Correlation effects are introduced using diagrammatic many-body theory to the level of the random-phase approximation with exchange (RPAE). Our aim is to provide an ab initio route to correlated multi-photon processes that are required for an accurate description of experiments on the attosecond time scale. Here, our results are focused on photoionization of the M -shell of argon atoms, where experiments have been carried out using the so-called RABITT technique. An influence of autoionizing resonances in attosecond delay measurements is observed. Further, it is shown that the delay depends on both detection angle of the photoelectron and energy of the probe photon.Comment: 36 pages, 10 figure

Attosecond transient absorption of a bound wave packet coupled to a smooth continuum

We investigate the possibility to use transient absorption of a coherent bound electron wave packet in hydrogen as an attosecond pulse characterization technique. In recent work we have shown that photoionization of such a coherent bound electron wave packet opens up for pulse characterization with unprecedented temporal accuracy --- independent of the atomic structure --- with maximal photoemission at all kinetic energies given a wave packet with zero relative phase [Pabst and Dahlstr\"om, Phys. Rev. A, 94, 13411 (2016)]. Here, we perform numerical propagation of the time-dependent Schr\"odinger equation and analytical calculations based on perturbation theory to show that the energy-resolved maximal absorption of photons from the attosecond pulse does not uniquely occur at zero relative phase of the initial wave packet. Instead, maximal absorption occurs at different relative wave packet phases, distributed as a non-monotonous function with a smooth $-\pi/2$ shift across the central photon energy (given a Fourier-limited Gaussian pulse). Similar results are found also in helium. Our finding is surprising because it implies that the energy-resolved photoelectrons are not mapped one-to-one with the energy-resolved absorbed photons of the attosecond pulse.Comment: 10 pages, 8 figues, submitted as part of a Special Issue on Emerging Attosecond Technologies in Journal of Optic

Attosecond dynamics of light-induced resonant hole transfer in high-order-harmonic generation

We present a study of high-order-harmonic generation (HHG) assisted by extreme ultraviolet (XUV) attosecond pulses, which can lead to the excitation of inner-shell electrons and the generation of a second HHG plateau. With the treatment of a one-dimensional model of krypton, based on time-dependent configuration interaction singles (TDCIS) of an effective two-electron system, we show that the XUV-assisted HHG spectrum reveals the duration of the semiclassical electron trajectories. The results are interpreted by the strong-field approximation (SFA) and the importance of the hole transfer during the tunneling process is emphasized. Finally, coherent population transfer between the inner and outer holes with attosecond pulse trains is discussed.Comment: 13 pages, 8 figure

Attosecond photoionization dynamics with stimulated core-valence transitions

We investigate ionization of neon atoms by an isolated attosecond pump pulse in the presence of two coherent extreme ultraviolet or x-ray probe fields. The probe fields are tuned to a core-valence transition in the residual ion and induce spectral shearing of the photoelectron distributions. We show that the photoelectron-ion coincidence signal contains an interference pattern that depends on the temporal structure of the attosecond pump pulse and the stimulated core-valence transition. Many-body perturbation theory is used to compute "atomic response times" for the processes and we find strikingly different behavior for stimulation to the outer-core hole (2p - 2s) and stimulation to the inner-core hole (2p - 1s). The response time of the inner-core transition is found to be comparable to that of state-of-the-art laser-based characterization techniques for attosecond pulses.Comment: 12 pages, 5 figure

The Multi-Configurational Hartree-Fock close-coupling ansatz: application to Argon photoionization cross section and delays

We present a robust, ab initio method for addressing atom-light interactions and apply it to photoionization of argon. We use a close-coupling ansatz constructed on a multi-configurational Hartree-Fock description of localized states and B-spline expansions of the electron radial wave functions. In this implementation, the general many-electron problem can be tackled thanks to the use of the ATSP2K libraries [CPC 176 (2007) 559]. In the present contribution, we combine this method with exterior complex scaling, thereby allowing for the computation of the complex partial amplitudes that encode the whole dynamics of the photoionization process. The method is validated on the 3s3p6np series of resonances converging to the 3s extraction. Then, it is used for computing the energy dependent differential atomic delay between 3p and 3s photoemission, and agreement is found with the measurements of Gu\'enot et al. [PRA 85 (2012) 053424]. The effect of the presence of resonances in the one-photon spectrum on photoionization delay measurements is studied.Comment: 15 pages, 8 figures, 4 table