Parametric resonances in a base-excited double pendulum

Two parametrically-induced phenomena are addressed in the context of a double pendulum subject to a vertical base excitation. First, the parametric resonances that cause the stable downward vertical equilibrium to bifurcate into large-amplitude periodic solutions are investigated extensively. Then the stabilization of the unstable upward equilibrium states through the parametric action of the high-frequency base motion is documented in the experiments and in the simulations. It is shown that there is a region in the plane of the excitation frequency and amplitude where all four unstable equilibrium states can be stabilized simultaneously in the double pendulum. The parametric resonances of the two modes of the base-excited double pendulum are studied both theoretically and experimentally. The transition curves (i.e., boundaries of the dynamic instability regions) are constructed asymptotically via the method of multiple scales including higher-order effects. The bifurcations characterizing the transitions from the trivial equilibrium to the periodic solutions are computed by either continuation methods and or by time integration and compared with the theoretical and experimental results.

Alteration of distortion product otoacoustic emission input/output functions in subjects with a previous history of middle ear dysfunction

Background: The aim of this study was to investigate the effects of sub-clinical alterations on the amplitudes and slopes of the DPOAE input-output responses from subjects with previous history of middle ear dysfunction. Material/Methods: The study included 15 subjects with and 15 subjects without a history of otitis media in the last 10 years. All participants were assessed with acoustic immittance, pure-tone audiometry, and DPOAEs. For the later, I/O functions and I/O slopes were estimated at 1501, 2002, 3174, 4004 and 6384Hz. Results: No statistically significant differences were found between the 2 groups in terms of behavioral thresholds. The group with a previous history of middle ear dysfunction presented significantly lower mean DPOAE amplitudes at 2002, 3174 and 4004 Hz. In terms of DPOAE slopes, no statistically significant differences were observed at the tested frequencies, except at 3174 Hz. Conclusions: Middle ear pathologies can produce subclinical alterations that are undetectable with traditional pure-tone audiometry. The data from the present study show that reduced amplitude DPOAEs are associated with a previous history of middle ear complications. The corresponding DPOAE slopes were affected at only 1 tested frequency, suggesting that the cochlear non-linearity is preserved. Considering these results, it remains to be elucidated to what degree the DPOAE amplitude attenuation interferes with higher-order auditory tasks.

Verwendung von Präzisionsmessungen zur Eingrenzung von Effekten jenseits des Standardmodells mittels eines effektiven feldtheoretischen Zugangs

Es gibt kaum eine präzisere Beschreibung der Natur als die durch das Standardmodell der Elementarteilchen (SM). Es ist in der Lage bis auf wenige Ausnahmen, die Physik der Materie- und Austauschfelder zu beschreiben. Dennoch ist man interessiert an einer umfassenderen Theorie, die beispielsweise auch die Gravitation mit einbezieht, Neutrinooszillationen beschreibt, und die darüber hinaus auch weitere offene Fragen klärt. Um dieser Theorie ein Stück näher zu kommen, befasst sich die vorliegende Arbeit mit einem effektiven Potenzreihenansatz zur Beschreibung der Physik des Standardmodells und neuer Phänomene. Mit Hilfe eines Massenparameters und einem Satz neuer Kopplungskonstanten wird die Neue Physik parametrisiert. In niedrigster Ordnung erhält man das bekannte SM, Terme höherer Ordnung in der Kopplungskonstanten beschreiben die Effekte jenseits des SMs. Aus gewissen Symmetrie-Anforderungen heraus ergibt sich eine definierte Anzahl von effektiven Operatoren mit Massendimension sechs, die den hier vorgestellten Rechnungen zugrunde liegen. Wir berechnen zunächst für eine bestimmte Auswahl von Prozessen zugehörige Zerfallsbreiten bzw. Wirkungsquerschnitte in einem Modell, welches das SM um einen einzigen neuen effektiven Operator erweitertet. Unter der Annahme, dass der zusätzliche Beitrag zur Observablen innerhalb des experimentellen Messfehlers ist, geben wir anhand von vorliegenden experimentellen Ergebnissen aus leptonischen und semileptonischen Präzisionsmessungen Ausschlussgrenzen der neuen Kopplungen in Abhängigkeit von dem Massenparameter an. Die hier angeführten Resultate versetzen Physiker zum Einen in die Lage zu beurteilen, bei welchen gemessenen Observablen eine Erhöhung der Präzision sinnvoll ist, um bessere Ausschlussgrenzen angeben zu können. Zum anderen erhält man einen Anhaltspunkt, welche Prozesse im Hinblick auf Entdeckungen Neuer Physik interessant sind.

Trait emotional intelligence: Evidence from italian adolescents and adults

Emotional intelligence (EI) represents an attribute of contemporary attractiveness for the scientific psychology community. Of particular interest for the present thesis are the conundrum related to the representation of this construct conceptualized as a trait (i.e., trait EI), which are in turn reflected in the current lack of agreement upon its constituent elements, posing significant challenges to research and clinical progress. Trait EI is defined as an umbrella personality-alike construct reflecting emotion-related dispositions and self-perceptions. The Trait Emotional Intelligence Questionnaire (TEIQue) was chosen as main measure, given its strong theoretical and psychometrical basis, including superior predictive validity when compared to other trait EI measures. Studies 1 and 2 aimed at validating the Italian 153-items forms of the TEIQue devoted to adolescents and adults. Analyses were done to investigate the structure of the questionnaire, its internal consistencies and gender differences at the facets, factor, and global level of both versions. Despite some low reliabilities, results from Studies 1 and 2 confirm the four-factor structure of the TEIQue. Study 3 investigated the utility of trait EI in a sample of adolescents over internalizing conditions (i.e., symptoms of anxiety and depression) and academic performance (grades at math and Italian language/literacy). Beyond trait EI, concurrent effects of demographic variables, higher order personality dimensions and non-verbal cognitive ability were controlled for. Study 4a and Study 4b addressed analogue research questions, through a meta-analysis and new data in on adults. In the latter case, effects of demographics, emotion regulation strategies, and the Big Five were controlled. Overall, these studies showed the incremental utility of the TEIQue in different domains beyond relevant predictors. Analyses performed at the level of the four-TEIQue factors consistently indicated that its predictive effects were mainly due to the factor Well-Being. Findings are discussed with reference to potential implication for theory and practice.

Sensing applications of biofunctionalised plasmonic gold nanoparticles

Plasmonische Metallnanopartikel bündeln, verstärken und beeinflussen Licht auf nanoskopischer Ebene. Diese grundlegende Eigenschaft kommt von koheränten, kollektiven Schwingungen der Leitungsbandelektronen, die von einfallendem Licht resonant angeregt und lokalisierte Oberflächenplasmonenresonanz (LSPR) oder ‚Partikelplasmonen‘ genannt werden. Plasmonen in Metallnanopartikeln wurden bisher z.B. zur Erkennen von pathogenen Biomolekülen, bei der photothermischen Therapie und zur Verbesserung der Effizienz von Solarzellen verwendet. In dieser Arbeit werde ich meinen Fokus auf die Synthese und Funktionalisierung von Goldnanopartikeln zur Anwendung als Sensoren legen.rnrnKürzliche Verbesserungen in der nasschemischen Synthese haben zur Herstellung von Goldnanopartikel mit unterschiedlichen Formen und Größen geführt, die sich in ihren Sensoreigenschaften unterscheiden. Unter den unterschiedlichen Sensorgeometrien sind Goldnanostäbchen die bevorzugte Form zur Biomolekül-Sensorik durch LSPR. Nanostäbchen werden durch eine positiv geladene CTAB-Schicht stabilisiert, die Proteine bei neutralem pH-Wert anziehen kann. Die Adsorption und Desorption von Proteinen an der Nanopartikeloberfläche und damit die Bindungskinetiken von Proteinen kann auf Einzelmolekülebene erforscht werden. Ich zeige hier eine Studie mit hoher örtlicher und zeitlicher Auflösung um einzelne Bindungsereignisse von Fibronectin auf Goldnanostäbchen darzustellen.rnrnGoldnanostäbchen müssen mit spezifischen biologischen Erkennungselementen funktionalisiert werden um eine Analyterkennung oder Proteinwechselwirkung zu erreichen. Ich funktionalisiere Goldnanostäbchen mit kurzen DNA-Sequenzen (Aptamer-Sequenzen und NTA konjugierten Polihymidinen) und habe anhand diese unterschiedlich sensitiven Partikel eine Studie mit verschiedenen Analyten (oder Protein-Protein Wechselwirkungen) erfolgreich durchgeführt.rn rnPlasmonen von Nanopartikel-Clustern koppeln miteinander, was ihre Resonanzenergie ändert. Der kontrollierte Zusammenbau von Nanopartikeln zu Dimeren oder höher geordneten Strukturen wie ‚Core-Satellites‘ können dazu dienen ihre Sensitivität zu erhöhen. Diese Cluster bieten eine hohe Sensitivität auf Grund der Anwesenheit von plasmonischen Hotspots in der Lücke zwischen zwei Partikeln. Die Plasmonkopplung ist ein Phänomen, das abhängig vom Abstand zweier Partikel zueinander ist und bildet somit die Basis von sogenannten Plasmon-Linealen. Ich habe eine Strategie entwickelt um Dimere aus Hsp90 funktionalisierten Goldnanosphären zu bilden. Diese Technik wird nicht durch Ausbleichen oder das Blinken von Farbstoffen limitiert und ich zeige zum ersten Mal wie man dadurch dynamische Proteinkonformationen untersuchen kann.rn

Imagery of a moving object: the role of occipital cortex and human MT/V5+

Visual imagery – similar to visual perception – activates feature-specific and category-specific visual areas. This is frequently observed in experiments where the instruction is to imagine stimuli that have been shown immediately before the imagery task. Hence, feature-specific activation could be related to the short-term memory retrieval of previously presented sensory information. Here, we investigated mental imagery of stimuli that subjects had not seen before, eliminating the effects of short-term memory. We recorded brain activation using fMRI while subjects performed a behaviourally controlled guided imagery task in predefined retinotopic coordinates to optimize sensitivity in early visual areas. Whole brain analyses revealed activation in a parieto-frontal network and lateral–occipital cortex. Region of interest (ROI) based analyses showed activation in left hMT/V5+. Granger causality mapping taking left hMT/V5+ as source revealed an imagery-specific directed influence from the left inferior parietal lobule (IPL). Interestingly, we observed a negative BOLD response in V1–3 during imagery, modulated by the retinotopic location of the imagined motion trace. Our results indicate that rule-based motion imagery can activate higher-order visual areas involved in motion perception, with a role for top-down directed influences originating in IPL. Lower-order visual areas (V1, V2 and V3) were down-regulated during this type of imagery, possibly reflecting inhibition to avoid visual input from interfering with the imagery construction. This suggests that the activation in early visual areas observed in previous studies might be related to short- or long-term memory retrieval of specific sensory experiences.

Whither PQL?

Generalized linear mixed models (GLMM) are generalized linear models with normally distributed random effects in the linear predictor. Penalized quasi-likelihood (PQL), an approximate method of inference in GLMMs, involves repeated fitting of linear mixed models with “working” dependent variables and iterative weights that depend on parameter estimates from the previous cycle of iteration. The generality of PQL, and its implementation in commercially available software, has encouraged the application of GLMMs in many scientific fields. Caution is needed, however, since PQL may sometimes yield badly biased estimates of variance components, especially with binary outcomes. Recent developments in numerical integration, including adaptive Gaussian quadrature, higher order Laplace expansions, stochastic integration and Markov chain Monte Carlo (MCMC) algorithms, provide attractive alternatives to PQL for approximate likelihood inference in GLMMs. Analyses of some well known datasets, and simulations based on these analyses, suggest that PQL still performs remarkably well in comparison with more elaborate procedures in many practical situations. Adaptive Gaussian quadrature is a viable alternative for nested designs where the numerical integration is limited to a small number of dimensions. Higher order Laplace approximations hold the promise of accurate inference more generally. MCMC is likely the method of choice for the most complex problems that involve high dimensional integrals.

Wind plant interaction with series-compensated power systems

Wind power based generation has been rapidly growing world-wide during the recent past. In order to transmit large amounts of wind power over long distances, system planners may often add series compensation to existing transmission lines owing to several benefits such as improved steady-state power transfer limit, improved transient stability, and efficient utilization of transmission infrastructure. Application of series capacitors has posed resonant interaction concerns such as through subsynchronous resonance (SSR) with conventional turbine-generators. Wind turbine-generators may also be susceptible to such resonant interactions. However, not much information is available in literature and even engineering standards are yet to address these issues. The motivation problem for this research is based on an actual system switching event that resulted in undamped oscillations in a 345-kV series-compensated, typical ring-bus power system configuration. Based on time-domain ATP (Alternative Transients Program) modeling, simulations and analysis of system event records, the occurrence of subsynchronous interactions within the existing 345-kV series-compensated power system has been investigated. Effects of various small-signal and large-signal power system disturbances with both identical and non-identical wind turbine parameters (such as with a statistical-spread) has been evaluated. Effect of parameter variations on subsynchronous oscillations has been quantified using 3D-DFT plots and the oscillations have been identified as due to electrical self-excitation effects, rather than torsional interaction. Further, the generator no-load reactance and the rotor-side converter inner-loop controller gains have been identified as bearing maximum sensitivity to either damping or exacerbating the self-excited oscillations. A higher-order spectral analysis method based on modified Prony estimation has been successfully applied to the field records identifying dominant 9.79 Hz subsynchronous oscillations. Recommendations have been made for exploring countermeasures.

Impaired gesture performance in schizophrenia: particular vulnerability of meaningless pantomimes

Schizophrenia patients frequently present with subtle motor impairments, including higher order motor function such as hand gesture performance. Using cut off scores from a standardized gesture test, we previously reported gesture deficits in 40% of schizophrenia patients irrespective of the gesture content. However, these findings were based on normative data from an older control group. Hence, we now aimed at determining cut-off scores in an age and gender matched control group. Furthermore, we wanted to explore whether gesture categories are differentially affected in Schizophrenia. Gesture performance data of 30 schizophrenia patients and data from 30 matched controls were compared. Categories included meaningless, intransitive (communicative) and transitive (object related) hand gestures, which were either imitated or pantomimed, i.e. produced on verbal command. Cut-off scores of the age matched control group were higher than the previous cut-off scores in an older control group. An ANOVA tested effects of group, domain (imitation or pantomime), and semantic category (meaningless, transitive or intransitive), as well as their interaction. According to the new cut-off scores, 67% of the schizophrenia patients demonstrated gestural deficits. Patients performed worse in all gesture categories, however meaningless gestures on verbal command were particularly impaired (p = 0.008). This category correlated with poor frontal lobe function (p < 0.001). In conclusion, gestural deficits in schizophrenia are even more frequent than previously reported. Gesture categories that pose higher demands on planning and selection such as pantomime of meaningless gestures are predominantly affected and associated with the well-known frontal lobe dysfunction.

Self-motion perception influences number processing: evidence from a parity task

We investigated the role of horizontal body motion on the processing of numbers. We hypothesized that leftward self-motion leads to shifts in spatial attention and therefore facilitates the processing of small numbers, and vice versa, we expected that rightward self-motion facilitates the processing of large numbers. Participants were displaced by means of a motion platform during a parity judgment task. We found a systematic influence of self-motion direction on number processing, suggesting that the processing of numbers is intertwined with the processing of self-motion perception. The results differed from known spatial numerical compatibility effects in that self-motion exerted a differential influence on inner and outer numbers of the given interval. The results highlight the involvement of sensory body motion information in higher-order spatial cognition.

Balancing the mind: vestibular induced facilitation of egocentric mental transformations

The body schema is a key component in accomplishing egocentric mental transformations, which rely on bodily reference frames. These reference frames are based on a plurality of different cognitive and sensory cues among which the vestibular system plays a prominent role. We investigated whether a bottom-up influence of vestibular stimulation modulates the ability to perform egocentric mental transformations. Participants were significantly faster to make correct spatial judgments during vestibular stimulation as compared to sham stimulation. Interestingly, no such effects were found for mental transformation of hand stimuli or during mental transformations of letters, thus showing a selective influence of vestibular stimulation on the rotation of whole-body reference frames. Furthermore, we found an interaction with the angle of rotation and vestibular stimulation demonstrating an increase in facilitation during mental body rotations in a direction congruent with rightward vestibular afferents. We propose that facilitation reflects a convergence in shared brain areas that process bottom-up vestibular signals and top-down imagined whole-body rotations, including the precuneus and tempero-parietal junction. Ultimately, our results show that vestibular information can influence higher-order cognitive processes, such as the body schema and mental imagery.

GOCE: assessment of GPS-only gravity field determination

The GOCE satellite was orbiting the Earth in a Sun-synchronous orbit at a very low altitude for more than 4 years. This low orbit and the availability of high-quality data make it worthwhile to assess the contribution of GOCE GPS data to the recovery of both the static and time-variable gravity fields. We use the kinematic positions of the official GOCE precise science orbit (PSO) product to perform gravity field determination using the Celestial Mechanics Approach. The generated gravity field solutions reveal severe systematic errors centered along the geomagnetic equator. Their size is significantly coupled with the ionospheric density and thus generally increasing over the mission period. The systematic errors may be traced back to the kinematic positions of the PSO product and eventually to the ionosphere-free GPS carrier phase observations used for orbit determination. As they cannot be explained by the current higher order ionospheric correction model recommended by the IERS Conventions 2010, an empirical approach is presented by discarding GPS data affected by large ionospheric changes. Such a measure yields a strong reduction of the systematic errors along the geomagnetic equator in the gravity field recovery, and only marginally reduces the set of useable kinematic positions by at maximum 6 % for severe ionosphere conditions. Eventually it is shown that GOCE gravity field solutions based on kinematic positions have a limited sensitivity to the largest annual signal related to land hydrology.

Binding of Metallocenes to Short Oligonucleotides

Cancer is one of the most severe and widespread diseases and an ideal treatment has not yet been found. In the last decades, cisplatinum was commonly applied in cancer therapy with very good results. However, serious side effects and resistant tumors necessitated the development of new antineoplastic agents, such as metallocenes dihalides. These are metal-based compounds exhibiting two cyclopentadienyl ligands and a cis-dihalide motif. They resemble the cis-chloro configuration of cisplatinum, which propounds a similar mode of action. Metallocenes comprising one of the transition metals titanium, molybdenum, vanadium, niobium, and zirconium as the metal center have been shown to be effective against several cancer cell lines. Evidence for the accumulation of metallocenes in the nucleus implied that DNA is one of the major targets. Although several studies reported adduct formation of metallocenes with nuclear DNA, as yet substantial information about the general binding pattern and the binding to higher-order structures is lacking. Mass spectrometry can fill this gap as it constitutes a powerful technique to investigate the formation of organometallic adducts. Presented data demonstrate that the two agents titanocene dichloride and molybdenocene dichloride bind to single-stranded DNA and RNA. Distinct fragment ions formed upon collision-induced dissociation help to unravel preferential binding sites within the oligonucleotides. Moreover, adducts with duplexes and quadruplexes shed light on the molecular mechanism of action.

Genetic variants in the mammalian target of rapamycin (mTOR) signaling pathway as predictors of survival and clinical response in women with ovarian cancer

Background. The mTOR pathway is commonly altered in human tumors and promotes cell survival and proliferation. Preliminary evidence suggests this pathway's involvement in chemoresistance to platinum and taxanes, first line therapy for epithelial ovarian cancer. A pathway-based approach was used to identify individual germline single nucleotide polymorphisms (SNPs) and cumulative effects of multiple genetic variants in mTOR pathway genes and their association with clinical outcome in women with ovarian cancer. ^ Methods. The case-series was restricted to 319 non-Hispanic white women with high grade ovarian cancer treated with surgery and platinum-based chemotherapy. 135 SNPs in 20 representative genes in the mTOR pathway were genotyped. Hazard ratios (HRs) for death and Odds ratios (ORs) for failure to respond to primary therapy were estimated for each SNP using the multivariate Cox proportional hazards model and multivariate logistic regression model, respectively, while adjusting for age, stage, histology and treatment sequence. A survival tree analysis of SNPs with a statistically significant association (p<0.05) was performed to identify higher order gene-gene interactions and their association with overall survival. ^ Results. There was no statistically significant difference in survival by tumor histology or treatment regimen. The median survival for the cohort was 48.3 months. Seven SNPs were significantly associated with decreased survival. Compared to those with no unfavorable genotypes, the HR for death increased significantly with the increasing number of unfavorable genotypes and women in the highest risk category had HR of 4.06 (95% CI 2.29–7.21). The survival tree analysis also identified patients with different survival patterns based on their genetic profiles. 13 SNPs on five different genes were found to be significantly associated with a treatment response, defined as no evidence of disease after completion of primary therapy. Rare homozygous genotype of SNP rs6973428 showed a 5.5-fold increased risk compared to the wild type carrying genotypes. In the cumulative effect analysis, the highest risk group (individuals with ≥8 unfavorable genotypes) was significantly less likely to respond to chemotherapy (OR=8.40, 95% CI 3.10–22.75) compared to the low risk group (≤4 unfavorable genotypes). ^ Conclusions. A pathway-based approach can demonstrate cumulative effects of multiple genetic variants on clinical response to chemotherapy and survival. Therapy targeting the mTOR pathway may modify outcome in select patients.^

Molecular mechanism of the relaxin signaling pathways: Activation of cAMP, PI3K, and PKCzeta

Relaxin is a polypeptide hormone that has diverse effects on reproductive and non-reproductive tissues. Relaxin activates the G-protein coupled receptors, LGR7 and LRG8. Early studies described increased cAMP and protein kinase A activity upon relaxin treatment, but cAMP accumulation alone could not account for all of the relaxin-mediated effects. We utilized the human monocyte cell line THP-1 to study the mechanism of relaxin-stimulated CAMP production. ^ Relaxin treatment in THP-1 cells produces a biphasic time course in cAMP accumulation, where the first peak appears as early as 1–2 minutes with a second peak at 10–20 minutes. Selective inhibitors for phosphoinositide 3-kinase (P13K), such as wortmannin and LY294002, show a dose-dependent inhibition of relaxin-stimulated cAMP accumulation, specific for the second peak of the relaxin time course. Neither the effects of relaxin nor the inhibition of relaxin by LY294002 is mediated by the activity of phosphodiesterases. Furthermore, LY294002 blocks upregulation of vascular endothelial growth factor transcript levels by relaxin. ^ To further delineate relaxin signaling pathways, we searched for downstream targets of PI3K that could activate adenylyl cyclase (AC). Protein kinase C ζ (PKCζ) was a prime candidate because it activates types II and V AC. Chelerythrine chloride (a general PKC inhibitor) inhibits relaxin-induced cAMP production to the same degree as LY294002 (∼40%). Relaxin stimulates PKCζ translocation to the plasma membrane in THP-1, MCF-7, PHM1-31, and MMC cells, as shown by immunocytochemistry. PKCζ translocation is P13K-dependent and independent of cAMP production. Antisense PKCζ oligodeoxynucleotides (PKCζ-ODNs) deplete both PKCζ transcript and protein levels in THP-1 cells. PKCζ-ODNs abolish relaxin-mediated PKCζ translocation and inhibit relaxin stimulation of cAMP by 40%, as compared to mock and random ODN controls. Treatment with LY294002 in the presence of PKCζ-ODNs results in little further inhibition. Taken together, we present a novel role for PI3K and PKCζ in relaxin stimulation of cAMP and provide the first example of the PKCζ regulation of AC in an endogenous system. Furthermore, we have identified higher order complexes of AC isoforms and PKA anchoring proteins in attempts to explain the differential coupling of relaxin to cAMP and PI3K-signaling pathways in various cell types. ^