Non-Gaussianities from a sudden change in the inflaton speed of sound

Il concetto di inflazione e' stato introdotto nei primi anni ’80 per risolvere alcuni problemi del modello cosmologico standard, quali quello dell’orizzonte e quello della piattezza. Le predizioni dei piu' semplici modelli inflazionari sono in buon accordo con le osservazioni cosmologiche piu'recenti, che confermano sezioni spaziali piatte e uno spettro di fluttuazioni primordiali con statistica vicina a quella gaussiana. I piu' recenti dati di Planck, pur in ottimo accordo con una semplice legge di potenza per lo spettro a scale k > 0.08 Mpc−1 , sembrano indicare possibili devi- azioni a scale maggiori, seppur non a un livello statisticamente significativo a causa della varianza cosmica. Queste deviazioni nello spettro possono essere spiegate da modelli inflazionari che includono una violazione della condizione di lento rotolamento (slow-roll ) e che hanno precise predizioni per lo spettro. Per uno dei primi modelli, caratterizzato da una discontinuita' nella derivata prima del potenziale proposto da Starobinsky, lo spettro ed il bispettro delle fluttuazioni primordiali sono noti analiticamente. In questa tesi estenderemo tale modello a termini cinetici non standard, calcolandone analiticamente il bispettro e confrontando i risultati ottenuti con quanto presente in letteratura. In particolare, l’introduzione di un termine cinetico non standard permettera' di ottenere una velocita' del suono per l’inflatone non banale, che consentira' di estendere i risultati noti, riguardanti il bispettro, per questo modello. Innanzitutto studieremo le correzioni al bispettro noto in letteratura dovute al fatto che in questo caso la velocita' del suono e' una funzione dipendente dal tempo; successivamente, cercheremo di calcolare analiticamente un ulteriore contributo al bispettro proporzionale alla derivata prima della velocita' del suono (che per il modello originale e' nullo).

Determination of Pelvic Orientation from Ultrasound Images Using Patch-SSMs and a Hierarchical Speed of Sound Compensation Strategy

In the field of computer assisted orthopedic surgery (CAOS) the anterior pelvic plane (APP) is a common concept to determine the pelvic orientation by digitizing distinct pelvic landmarks. As percutaneous palpation is - especially for obese patients - known to be error-prone, B-mode ultrasound (US) imaging could provide an alternative means. Several concepts of using ultrasound imaging to determine the APP landmarks have been introduced. In this paper we present a novel technique, which uses local patch statistical shape models (SSMs) and a hierarchical speed of sound compensation strategy for an accurate determination of the APP. These patches are independently matched and instantiated with respect to associated point clouds derived from the acquired ultrasound images. Potential inaccuracies due to the assumption of a constant speed of sound are compensated by an extended reconstruction scheme. We validated our method with in-vitro studies using a plastic bone covered with a soft-tissue simulation phantom and with a preliminary cadaver trial.

Referral practice among Swiss and non-Swiss walk-in patients in an urban surgical emergency department

To assess the relationship between nationality, gender and age and use of health services among patients visiting an urban university hospital emergency department (ED).

Heart valve sound of various mechanical composite grafts, and the impact on patients' quality of life

The closing sounds of mechanical heart valves can be disturbing for patients and their closest relatives. Although some investigations into mechanical heart valve sounds have been performed, the particularities of the valve sound when it is attached to a vascular prosthesis to replace the aortic root and the ascending aorta has not been studied to date. The study aim was to compare the closing sounds of three various mechanical composite graft prostheses, and to analyze the impact of such sounds on the patients' quality of life.

[Evaluation of a preschool program to promote phonological awareness and letter-sound correspondence--long-term effects in the prevention of dyslexia at the end of the 3rd and 4th grades]

The present study evaluates the long-term effects of a preschool training in phonological awareness and letter- sound correspondence.

Is computer-assisted telephone triage safe? A prospective surveillance study in walk-in patients with non-life-threatening medical conditions

Background Patients often establish initial contact with healthcare institutions by telephone. During this process they are frequently medically triaged. Purpose To investigate the safety of computer-assisted telephone triage for walk-in patients with non-life-threatening medical conditions at an emergency unit of a Swiss university hospital. Methods This prospective surveillance study compared the urgency assessments of three different types of personnel (call centre nurses, hospital physicians, primary care physicians) who were involved in the patients' care process. Based on the urgency recommendations of the hospital and primary care physicians, cases which could potentially have resulted in an avoidable hazardous situation (AHS) were identified. Subsequently, the records of patients with a potential AHS were assessed for risk to health or life by an expert panel. Results 208 patients were enrolled in the study, of whom 153 were assessed by all three types of personnel. Congruence between the three assessments was low. The weighted κ values were 0.115 (95% CI 0.038 to 0.192) (hospital physicians vs call centre), 0.159 (95% CI 0.073 to 0.242) (primary care physicians vs call centre) and 0.377 (95% CI 0.279 to 0.480) (hospital vs primary care physicians). Seven of 153 cases (4.57%; 95% CI 1.85% to 9.20%) were classified as a potentially AHS. A risk to health or life was adjudged in one case (0.65%; 95% CI 0.02% to 3.58%). Conclusion Medical telephone counselling is a demanding task requiring competent specialists with dedicated training in communication supported by suitable computer technology. Provided these conditions are in place, computer-assisted telephone triage can be considered to be a safe method of assessing the potential clinical risks of patients' medical conditions.

Brain activation during anticipation of sound sequences

Music consists of sound sequences that require integration over time. As we become familiar with music, associations between notes, melodies, and entire symphonic movements become stronger and more complex. These associations can become so tight that, for example, hearing the end of one album track can elicit a robust image of the upcoming track while anticipating it in total silence. Here, we study this predictive “anticipatory imagery” at various stages throughout learning and investigate activity changes in corresponding neural structures using functional magnetic resonance imaging. Anticipatory imagery (in silence) for highly familiar naturalistic music was accompanied by pronounced activity in rostral prefrontal cortex (PFC) and premotor areas. Examining changes in the neural bases of anticipatory imagery during two stages of learning conditional associations between simple melodies, however, demonstrates the importance of fronto-striatal connections, consistent with a role of the basal ganglia in “training” frontal cortex (Pasupathy and Miller, 2005). Another striking change in neural resources during learning was a shift between caudal PFC earlier to rostral PFC later in learning. Our findings regarding musical anticipation and sound sequence learning are highly compatible with studies of motor sequence learning, suggesting common predictive mechanisms in both domains.

Comparisons of sound processors based on osseointegrated implants in patients with conductive or mixed hearing loss

To compare the patient benefit of the Bone-Anchored Hearing Aid (Baha) Divino and the Baha BP100 sound processors.