Cold Quark Matter

We perform an O(alpha_s^2) perturbative calculation of the equation of state of cold but dense QCD matter with two massless and one massive quark flavor, finding that perturbation theory converges reasonably well for quark chemical potentials above 1 GeV. Using a running coupling constant and strange quark mass, and allowing for further non-perturbative effects, our results point to a narrow range where absolutely stable strange quark matter may exist. Absent stable strange quark matter, our findings suggest that quark matter in compact star cores becomes confined to hadrons only slightly above the density of atomic nuclei. Finally, we show that equations of state including quark matter lead to hybrid star masses up to M~2M_solar, in agreement with current observations. For strange stars, we find maximal masses of M~2.75M_solar and conclude that confirmed observations of compact stars with M>2M_solar would strongly favor the existence of stable strange quark matter.Comment: 51 pages, 11 figures, v2: minor modifications and additional reference

Neural basis of acquired amusia and its recovery

In acquired amusia, the healthy music processing system in the brain is disrupted due to focal brain damage. This creates an exceptional opportunity to investigate the critical neural architectures of music processing. Yet, the neural basis of acquired amusia has remained largely unexplored. In this multimodal magnetic resonance imaging (MRI) study of stroke patients with a 6-month follow-up, we systematically explored the neural basis of music processing by determining the lesions patterns, structural grey and white matter changes, and brain activation and functional network connectivity changes associated with acquired amusia and its recovery. We found that damage to the right temporal areas, insula, and putamen forms the crucial neural substrate for acquired amusia after stroke. Longitudinally, persistent amusia was associated with further atrophy in the right superior temporal regions, located more anteriorly for rhythm-amusia and more posteriorly for pitchamusia. In addition, persistent amusia was associated with structural damage and later degeneration in multiple right frontotemporal and frontal pathways as well as interhemispheric connections. Interestingly, rhythm-amusia was associated with additional deficits in left frontal connectivity. During listening to instrumental music, acquired amusics exhibited dysfunction of multiple frontal and temporal brain regions included in the large-scale music network. Interestingly, amusics showed less activation deficits during listening to vocal music, as compared to instrumental music, suggesting less defective processing of singing. Recovery from acquired amusia was related to increased activation in the right frontal and parietal areas as well as increased functional connectivity in the right and left frontoparietal networks. Overall, the results provide a comprehensive neuroanatomical and functional picture of acquired amusia and highlight the neural structures crucial for normal music perception.Aivoinfarktin ja -verenvuodon jälkeinen musiikin käsittelyn häiriö ja siitä kuntoutuminen Hankinnaisessa amusiassa aivojen musiikinkäsittelyjärjestelmän normaali toiminta häiriintyy aivojen paikallisen vaurioitumisen takia. Tämä luo poikkeuksellisen mahdollisuuden tutkia musiikin käsittelylle tärkeitä aivorakenteita. Hankinnaisen amusian aivoperusta on kuitenkin suurelta osin vielä täysin tuntematonta. Tässä aivoverenkiertohäiriön (AVH) sairastaneiden potilaiden 6 kuukauden seurantatutkimuksessa selvitimme magneettikuvantamisen avulla musiikin käsittelyn aivoperustaa tutkimalla, minkä aivoalueiden vauriot, mitkä harmaan ja valkean aineen rakenteelliset muutokset ja millaiset aivojen toiminnalliset muutokset liittyvät hankinnaiseen amusiaan ja siitä kuntoutumiseen. Tuloksemme osoittivat, että AVH:n jälkeinen amusia syntyy oikean ohimolohkon yläosan, aivosaaren ja tyvitumakealueen vauriosta. Pysyvään amusiaan liittyi lisäksi harmaan aineen atrofiaa oikeassa ohimolohkossa. Rytmin havaitsemiseen liittyvässä amusiassa atrofia painottui ohimolohkon etuosaan ja äänenkorkeuden havaitsemiseen liittyvässä amusiassa ohimolohkon takaosaan. Lisäksi, pysyvään amusiaan liittyi laaja oikean aivopuoliskon ja aivopuoliskon välisten radastojen vaurio ja atrofia. Amusia aiheutti myös laajamittaisia aivojen toimintahäiriöitä musiikin kuuntelun aikana. Mielenkiintoista on, että toimintahäiriöt olivat suurempia kuunneltaessa instrumentaalimusiikkia kuin laulettua musiikkia. Amusiasta kuntoutuminen oli yhteydessä toiminnallisten yhteyksien vahvistumiseen oikean sekä vasemman aivopuoliskon otsa- ja päälakilohkojen välillä. Tulokset antavat kattavan kuvan amusiaan johtavista aivovaurioista sekä siihen liittyvistä rakenteellisista ja toiminnallisista muutoksista. Lisäksi tulokset valottavat musiikin käsittelylle keskeisen tärkeitä aivorakenteita

Thermalization at intermediate coupling

We use the AdS/CFT conjecture to investigate the thermalization of large-N_c N=4 Super Yang-Mills plasma in the limit of large but finite 't Hooft coupling. On the gravity side, we supplement the type IIB supergravity action by the full set of O(\alpha'^3) operators, which enables us to derive O(\lambda^{-3/2}) corrections to the emission spectrum of prompt photons in one model of holographic thermalization. Decreasing the coupling strength from the \lambda=\infty limit, we observe a qualitative change in the way the photon spectral density approaches its thermal limit as a function of the photon energy. We interpret this behavior as a sign of the thermalization pattern of the plasma shifting from top/down towards bottom/up.Comment: 5 pages, 3 figures; v2: minor corrections, added reference

Golden oldies and silver brains : Deficits, preservation, learning, and rehabilitation effects of music in ageing-related neurological disorders

During the last decades, there have been major advances in mapping the brain regions that underlie our ability to perceive, experience, and produce music and how musical training can shape the structure and function of the brain. This progress has fueled and renewed clinical interest towards uncovering the neural basis for the impaired or preserved processing of music in different neurological disorders and how music-based interventions can be used in their rehabilitation and care. This article reviews our contribution to and the state-of-the-art of this field. We will provide a short overview outlining the key brain networks that participate in the processing of music and singing in the healthy brain and then present recent findings on the following key music-related research topics in neurological disorders: (i) the neural architecture underlying deficient processing of music (amusia), (ii) the preservation of singing in aphasia and music-evoked emotions and memories in Alzheimer's disease, (iii) the mnemonic impact of songs as a verbal learning tool, and (iv) the cognitive, emotional, and neural efficacy of music-based interventions and activities in the rehabilitation and care of major ageing-related neurological illnesses (stroke, Alzheimer's disease, and Parkinson's disease). (C) 2018 Elsevier Ltd. All rights reserved.Peer reviewe

Clinical and Neural Predictors of Treatment Response to Music Listening Intervention after Stroke

Patients with post-stroke impairments present often significant variation in response to therapeutic interventions. Recent studies have shown that daily music listening can aid post-stroke recovery of language and memory, but reliable predictors of treatment response are unknown. Utilizing data from the music intervention arms of a single-blind randomized controlled trial (RCT) on stroke patients (N = 31), we built regression models to predict the treatment response of a two-month music listening intervention on language skills and verbal memory with baseline demographic, clinical and musical data as well as fMRI data from a music listening task. Clinically, greater improvement in verbal memory and language skills after the music listening intervention were predicted by the severity of the initial deficit and educational level. Neurally, greater baseline fMRI activation during vocal music listening in the left parietal cortical and medial frontal areas predicted greater treatment-induced improvement in language skills and greater baseline engagement of the auditory network during instrumental music listening predicted improvement in both verbal memory and language skills. Our results suggest that clinical, demographic, and neuroimaging data predicts music listening treatment response. This data could be used clinically to target music-based treatments.Peer reviewe

Screening in YBCO at large wave vectors

We present experimental inelastic x-ray scattering (IXS) and ab initio time-dependent density-functional-theory (TDDFT) studies of YBa2Cu3O7-{\delta}. The response of the low-lying Ba 5p and Y 4p core electrons is shown to interact strongly with the Cu 3d and O 2p excitations, with important consequences on screening. The agreement between IXS and TDDFT results is excellent, apart from a new type of excitations, mainly related to loosely bound Ba electrons and significantly affected by correlations. This points to correlation mechanisms not fully described by TDDFT that might have a role in giving rise to antiscreening.Comment: 6 pages, 3 figure

Post-stroke enriched auditory environment induces structural connectome plasticity : secondary analysis from a randomized controlled trial

Post-stroke neuroplasticity and cognitive recovery can be enhanced by multimodal stimulation via environmental enrichment. In this vein, recent studies have shown that enriched sound environment (i.e., listening to music) during the subacute post-stroke stage improves cognitive outcomes compared to standard care. The beneficial effects of post-stroke music listening are further pronounced when listening to music containing singing, which enhances language recovery coupled with structural and functional connectivity changes within the language network. However, outside the language network, virtually nothing is known about the effects of enriched sound environment on the structural connectome of the recovering post-stroke brain. Here, we report secondary outcomes from a single-blind randomized controlled trial (NCT01749709) in patients with ischaemic or haemorrhagic stroke (N = 38) who were randomly assigned to listen to vocal music, instrumental music, or audiobooks during the first 3 post-stroke months. Utilizing the longitudinal diffusion-weighted MRI data of the trial, the present study aimed to determine whether the music listening interventions induce changes on structural white matter connectome compared to the control audiobook intervention. Both vocal and instrumental music groups increased quantitative anisotropy longitudinally in multiple left dorsal and ventral tracts as well as in the corpus callosum, and also in the right hemisphere compared to the audiobook group. Audiobook group did not show increased structural connectivity changes compared to both vocal and instrumental music groups. This study shows that listening to music, either vocal or instrumental promotes wide-spread structural connectivity changes in the post-stroke brain, providing a fertile ground for functional restoration.Peer reviewe

Size and distance estimation in virtual reality

Abstract. Interest in virtual reality (VR) has been on the rise in the recent few years. However, it is difficult to create virtual environments which provide realistic perception of scale for their users. We wanted to study how humans perceive scale in VR and ways to improve VR scale perception. We did a pilot test to see how design choices affect distance and height estimation in VR. For pilot tests we had nine test participants. Based on the experience gathered from the pilot test, we designed the main test. For the main test we had 44 participants. The main test showed similar results for distance estimating as earlier studies. Humans underestimated distances and heights in VR. Having a familiar size object cue, a VR model of a milk carton, next to the object improved height estimations.Koon ja etäisyyden arviointi virtuaalitodellisuudessa. Tiivistelmä. Kiinnostus virtuaalitodellisuuteen (VT) on ollut kasvavaa muutaman viime vuoden aikana. On kuitenkin vaikeaa tehdä virtuaalinen ympäristö, joka luo käyttäjilleen luonnollisen aistimuksen mittakaavasta. Halusimme tutkia, miten ihmiset hahmottavat skaalaa VR:ssä ja kuinka sitä voi parantaa. Teimme pilottitestejä, jotta näkisimme kuinka erilaiset suunnittelupäätökset vaikuttavat etäisyyden ja korkeuden arviointiin virtuaalitodellisuudessa. Pilottitesteissä oli yhdeksän osallistujaa. Pilottitestien pohjalta teimme laajemman testin, jossa hyödynsimme pilottitesteistä saatuja kokemuksia. Laajemmassa testissä oli 44 osallistujaa. Tämä testi tuotti samankaltaisia tuloksia etäisyyden arvioinnissa kuin aikaisemmat tutkimukset. Ihmiset aliarvioivat etäisyyksiä ja korkeuksia virtuaalitodellisuudessa. Kun esineen vieressä oli tunnetun kokoinen esine, maitopurkin virtuaalimalli, korkeuden arviointi parani