An investigation of the existence of a random walk model for the Nairobi stock market prices

The behaviour of the Nairobi stock market prices is examined, under the assumption that the series follow a Random Walk Model. An examination of the spectra of the first differences of the five series shows the existence of significant cycles in the low as well as in the high frequency ranges. In addition, important annual components and/or their harmonics do exist in some series. It is concluded that the Random Walk Model is not appropriate for the Nairobi stock market prices. It is further concluded that there is, therefore, no universal behaviour of stock market prices and that in some markets, such as the Nairobi market, prices may be predicted enabling speculators to make profit

Correlation between amygdala BOLD activity and frontal EEG asymmetry during real-time fMRI neurofeedback training in patients with depression

Real-time fMRI neurofeedback (rtfMRI-nf) is an emerging approach for studies and novel treatments of major depressive disorder (MDD). EEG performed simultaneously with an rtfMRI-nf procedure allows an independent evaluation of rtfMRI-nf brain modulation effects. Frontal EEG asymmetry in the alpha band is a widely used measure of emotion and motivation that shows profound changes in depression. However, it has never been directly related to simultaneously acquired fMRI data. We report the first study investigating electrophysiological correlates of the rtfMRI-nf procedure, by combining rtfMRI-nf with simultaneous and passive EEG recordings. In this pilot study, MDD patients in the experimental group (n=13) learned to upregulate BOLD activity of the left amygdala using an rtfMRI-nf during a happy emotion induction task. MDD patients in the control group (n=11) were provided with a sham rtfMRI-nf. Correlations between frontal EEG asymmetry in the upper alpha band and BOLD activity across the brain were examined. Average individual changes in frontal EEG asymmetry during the rtfMRI-nf task for the experimental group showed a significant positive correlation with the MDD patients' depression severity ratings, consistent with an inverse correlation between the depression severity and frontal EEG asymmetry at rest. Temporal correlations between frontal EEG asymmetry and BOLD activity were significantly enhanced, during the rtfMRI-nf task, for the amygdala and many regions associated with emotion regulation. Our findings demonstrate an important link between amygdala BOLD activity and frontal EEG asymmetry. Our EEG asymmetry results suggest that the rtfMRI-nf training targeting the amygdala is beneficial to MDD patients, and that alpha-asymmetry EEG-nf would be compatible with the amygdala rtfMRI-nf. Combination of the two could enhance emotion regulation training and benefit MDD patients.Comment: 28 pages, 16 figures, to appear in NeuroImage: Clinica

Chiral Zeromodes on Vortex-type Intersecting Heterotic Five-branes

We solve the gaugino Dirac equation on a smeared intersecting five-brane solution in E_8\times E_8 heterotic string theory to search for localized chiral zeromodes on the intersection. The background is chosen to depend on the full two-dimensional overall transverse coordinates to the branes. Under some appropriate boundary conditions, we compute the complete spectrum of zeromodes to find that, among infinite towers of Fourier modes, there exist only three localized normalizable zeromodes, one of which has opposite chirality to the other two. This agrees with the result previously obtained in the domain-wall type solution, supporting the claim that there exists one net chiral zeromode localized on the heterotic five-brane system.Comment: 10 pages, 2 figure

A photocaged orexin-B for spatiotemporally precise control of orexin signaling

Orexin neuropeptides carry out important neuromodulatory functions in the brain, yet tools to precisely control the activation of endogenous orexin signaling are lacking. Here, we developed a photocaged orexin-B (photo-OXB) through a C-terminal photocaging strategy. We show that photo-OXB is unable to activate its cognate receptors in the dark but releases functionally active native orexin-B upon uncaging by illumination with UV-visible (UV-vis) light (370–405 nm). We established an all-optical assay combining photo-OXB with a genetically encoded orexin biosensor and used it to characterize the efficiency and spatial profile of photo-OXB uncaging. Finally, we demonstrated that photo-OXB enables optical control over orexin signaling with fine temporal precision both in vitro and ex vivo. Thus, our photocaging strategy and photo-OXB advance the chemical biological toolkit by introducing a method for the optical control of peptide signaling and physiological function

TEAMwork: Testing Emotional Attunement and Mutuality During Parent-Adolescent fMRI.

The parent-child relationship and family context influence the development of emotion regulation (ER) brain circuitry and related skills in children and adolescents. Although both parents' and children's ER neurocircuitry simultaneously affect how they interact with one another, neuroimaging studies of parent-child relationships typically include only one member of the dyad in brain imaging procedures. The current study examined brain activation related to parenting and ER in parent-adolescent dyads during concurrent fMRI scanning with a novel task - the Testing Emotional Attunement and Mutuality (TEAM) task. The TEAM task includes feedback trials indicating the other dyad member made an error, resulting in a monetary loss for both participants. Results indicate that positive parenting practices as reported by the adolescent were positively correlated with parents' hemodynamic activation of the ventromedial prefrontal cortex, a region related to empathy, during these error trials. Additionally, during feedback conditions both parents and adolescents exhibited fMRI activation in ER-related regions, including the dorsolateral prefrontal cortex, anterior insula, fusiform gyrus, thalamus, caudate, precuneus, and superior parietal lobule. Adolescents had higher left amygdala activation than parents during the feedback condition. These findings demonstrate the utility of dyadic fMRI scanning for investigating relational processes, particularly in the parent-child relationship

Always on my mind: Cross-brain associations of mental health symptoms during simultaneous parent-child scanning.

How parents manifest symptoms of anxiety or depression may affect how children learn to modulate their own distress, thereby influencing the children's risk for developing an anxiety or mood disorder. Conversely, children's mental health symptoms may impact parents' experiences of negative emotions. Therefore, mental health symptoms can have bidirectional effects in parent-child relationships, particularly during moments of distress or frustration (e.g., when a parent or child makes a costly mistake). The present study used simultaneous functional magnetic resonance imaging (fMRI) of parent-adolescent dyads to examine how brain activity when responding to each other's costly errors (i.e., dyadic error processing) may be associated with symptoms of anxiety and depression. While undergoing simultaneous fMRI scans, healthy dyads completed a task involving feigned errors that indicated their family member made a costly mistake. Inter-brain, random-effects multivariate modeling revealed that parents who exhibited decreased medial prefrontal cortex and posterior cingulate cortex activation when viewing their child's costly error response had children with more symptoms of depression and anxiety. Adolescents with increased anterior insula activation when viewing a costly error made by their parent had more anxious parents. These results reveal cross-brain associations between mental health symptomatology and brain activity during parent-child dyadic error processing

Thermo-responsive Fluorescent Nanoparticles for Multimodal Imaging and Treatment of Cancers

Theranostic systems capable of delivering imaging and therapeutic agents at a specific target are the focus of intense research efforts in drug delivery. To overcome non-degradability and toxicity concerns of conventional theranostic systems, we formulated a novel thermo-responsive fluorescent polymer (TFP) and conjugated it on the surface of iron oxide magnetic nanoparticles (MNPs) for imaging and therapeutic applications in solid tumors. Methods: TFP-MNPs were synthesized by copolymerizing poly(N-isopropylacrylamide), allylamine and a biodegradable photoluminescent polymer, and conjugating it on MNPs via a free radical polymerization reaction. Physicochemical properties of the nanoparticles were characterized using Fourier transform infrared spectroscopy, dynamic light scattering, and vibrational sample magnetometry. Nanoparticle cytocompatibility, cellular uptake and cytotoxicity were evaluated using in vitro cell assays. Finally, in vivo imaging and therapeutic efficacy studies were performed in subcutaneous tumor xenograft mouse models. Results: TFP-MNPs of ~135 nm diameter and -31 mV ζ potential maintained colloidal stability and superparamagnetic properties. The TFP shell was thermo-responsive, fluorescent, degradable, and released doxorubicin in response to temperature changes. In vitro cell studies showed that TFP-MNPs were compatible to human dermal fibroblasts and prostate epithelial cells. These nanoparticles were also taken up by prostate and skin cancer cells in a dose-dependent manner and exhibited enhanced killing of tumor cells at 41°C. Preliminary in vivo studies showed theranostic capabilities of the nanoparticles with bright fluorescence, MRI signal, and therapeutic efficacy under magnetic targeting after systemic administration in tumor bearing mice. Conclusion: These results indicate the potential of TFP-MNPs as multifunctional theranostic nanoparticles for various biological applications, including solid cancer management

Evolution of superconductivity in isovalent Te-substituted KxFe2-ySe2 crystals

We report the evolution of superconductivity and the phase diagram of the KxFe2-ySe2-zTez (z=0-0.6) crystals grown by a simple one-step synthesis. No structural transition is observed in any crystals, while lattice parameters exhibit a systematic expansion with Te content. The Tc exhibits a gradual decrease with increasing Te content from Tconset = 32.9 K at z = 0 to Tconset = 27.9 K at z = 0.5, followed by a sudden suppression of superconductivity at z = 0.6. Upon approaching a Te concentration of 0.6, the shielding volume fraction decreases and eventually drops to zero. Simultaneously, hump positions in r-T curve shift to lower temperatures. These results suggest that isovalent substitution of Te for Se in KxFe2-ySe2 crystals suppresses the superconductivity in this system.Comment: 10 pages, 1 table, 8 figure