Letter by toscano et al regarding article. association of leukoaraiosis with convalescent rehabilitation outcome in patients with ischemic stroke

Given the aforementioned link between leukoaraiosis and swallowing impairment, and the burden of poststroke dysphagia on rehabilitation outcome, it could be of some interest to analyze the relationships between leukoaraiosis, recovery, and dysphagia in your large population

An investigation into the “beautification” of security ceremonies

“Beautiful Security” is a paradigm that requires security ceremonies to contribute to the ‘beauty’ of a user experience. The underlying assumption is that people are likely to be willing to engage with more beautiful security ceremonies. It is hoped that such ceremonies will minimise human deviations from the prescribed interaction, and that security will be improved as a consequence. In this paper, we explain how we went about deriving beautification principles, and how we tested the efficacy of these by applying them to specific security ceremonies. As a first step, we deployed a crowd-sourced platform, using both explicit and metaphorical questions, to extract general aspects associated with the perception of the beauty of real-world security mechanisms. This resulted in the identification of four beautification design guidelines. We used these to beautify the following existing security ceremonies: Italian voting, user-to-laptop authentication, password setup and EU premises access. To test the efficacy of our guidelines, we again leveraged crowd-sourcing to determine whether our “beautified” ceremonies were indeed perceived to be more beautiful than the original ones. The results of this initial foray into the beautification of security ceremonies delivered promising results, but must be interpreted carefully

Did Going North Give Us Migraine? An Evolutionary Approach on Understanding Latitudinal Differences in Migraine Epidemiology

This commentary discusses a recent publication by evolutionary biologists with strong implications for migraine experts. The Authors showed that a gene polymorphism associated with migraine gave our ancestors an evolutionary advantage when colonizing northern, and thus colder, territories. They then highlight that the prevalence of migraine may differ among countries because of climatic adaptation. These results may prove useful in planning both epidemiological and physiological studies in the field of migraine

Alice in wonderland syndrome. a clinical and pathophysiological review

Alice in Wonderland Syndrome (AIWS) is a perceptual disorder, principally involving visual and somesthetic integration, firstly reported by Todd, on the literary suggestion of the strange experiences described by Lewis Carroll in Alice in Wonderland books. Symptoms may comprise among others aschematia and dysmetropsia. This syndrome has many different etiologies; however EBV infection is the most common cause in children, while migraine affects more commonly adults. Many data support a strict relationship between migraine and AIWS, which could be considered in many patients as an aura or a migraine equivalent, particularly in children. Nevertheless, AIWS seems to have anatomical correlates. According to neuroimaging, temporoparietal- occipital carrefour (TPO-C) is a key region for developing many of AIWS symptoms. The final part of this review aims to find the relationship between AIWS symptoms, presenting a pathophysiological model. In brief, AIWS symptoms depend on an alteration of TPO-C where visual-spatial and somatosensory information are integrated. Alterations in these brain regions may cause the cooccurrence of dysmetropsia and disorders of body schema. In our opinion, the association of other symptoms reported in literature could vary depending on different etiologies and the lack of clear diagnostic criteria

Modelling of the Surface Emission of the Low-Magnetic Field Magnetar SGR 0418+5729

We perform a detailed modelling of the post-outburst surface emission of the low magnetic field magnetar SGR 0418+5729. The dipolar magnetic field of this source, B=6x10^12 G estimated from its spin-down rate, is in the observed range of magnetic fields for normal pulsars. The source is further characterized by a high pulse fraction and a single-peak profile. Using synthetic temperature distribution profiles, and fully accounting for the general-relativistic effects of light deflection and gravitational redshift, we generate synthetic X-ray spectra and pulse profiles that we fit to the observations. We find that asymmetric and symmetric surface temperature distributions can reproduce equally well the observed pulse profiles and spectra of SGR 0418. Nonetheless, the modelling allows us to place constraints on the system geometry (i.e. the angles $\psi$ and $\xi$ that the rotation axis makes with the line of sight and the dipolar axis, respectively), as well as on the spot size and temperature contrast on the neutron star surface. After performing an analysis iterating between the pulse profile and spectra, as done in similar previous works, we further employed, for the first time in this context, a Markov-Chain Monte-Carlo approach to extract constraints on the model parameters from the pulse profiles and spectra, simultaneously. We find that, to reproduce the observed spectrum and flux modulation: (a) the angles must be restricted to $65\deg < \psi+\xi < 125\deg$ or $235\deg < \psi+\xi <295\deg$; (b) the temperature contrast between the poles and the equator must be at least a factor of $\sim6$, and (c) the size of the hottest region ranges between 0.2-0.7 km (including uncertainties on the source distance). Last, we interpret our findings within the context of internal and external heating models.Comment: 13 pages, 10 figures. Accepted for publication in MNRA

Qual è la risposta del phytoplankton calcareo all’instaurarsi della calotta antartica durante la transizione Eocene-Oligocene?

Il sistema climatico dei nostri giorni, caratterizzato dalla presenza di ghiacci su entrambi i poli, è il risultato di un raffreddamento graduale avvenuto nel corso di decine di milioni di anni. La calotta Antartica permanente, si sviluppò 34 Ma, quando i detriti trasportati dal ghiaccio si depositarono per la prima volta sui sedimenti circostanti. Da quel momento, noto come la transizione Eocene-Oligocene (E/O), la calotta glaciale antartica è cresciuta in modo non uniforme fino ai giorni nostri. Questa transizione portò alla riorganizzazione degli ecosistemi marini e terrestri e aprì la strada all'istituzione della moderna circolazione termoalina. Questa tesi si concentra sulla risposta ecologica, biostratigrafica, morfometrica e preservazionale dei nannofossili calcarei, recuperati in diversi sedimenti provenienti dall’oceano Pacifico (Site IODP U1509; Site ODP U1209), Indiano (Site ODP 756) e Atlantico (Site IODP U1411). L'obiettivo è far luce sui tempi, le modalità e l'entità della loro risposta a cambiamenti legati alla chimica oceanica e all'espansione antartica. Questo studio documenta cambiamenti nell’associazione fitoplanctonica legati alla transizione stessa e alle principali escursioni isotopiche. I nannofossili calcarei hanno risposto in modo piuttosto sincrono all'espansione glaciale, registrando il passaggio da una comunità caldo-oligotrofica, che caratterizzava il tardo Priaboniano ad una fredda eutrofica nel primo Rupeliano. Questo turnover è stato innescato da una diminuzione di temperatura dell’acqua marina e da un aumento dei nutrienti (Capitolo 2 e Capitolo 4). Il dataset ad alta risoluzione fornisce anche un perfezionamento della biostratigrafia delle medio-basse latitudini e introduce nuovi biorizzonti potenzialmente utili che possono essere a loro volta integrati con altri, consentendo un confronto dettagliato tra alte e medio-basse latitudini (Capitolo 3). Clausicoccus subdistichus gr. si è rivelato uno straordinario indicatore biostratigrafico e paleoambientale per questo critico intervallo temporale. Il suo acme è presente e facilmente riconoscibile in tutti i siti studiati, perfino in un sedimento estremamente mal preservato (Site ODP 1209). La base comune (Bc) di C. subdistichus gr. rappresenta il migliore bioevento, tra quelli a nannofossili, per approssimare il limite EOB. I suoi picchi di abbondanza consentono una facile correlazione con il massimo glaciale dell'Oligocene inferiore - EOGM. In questo lavoro è stato ridefinito il ranking del limite superiore di abbondanza (Tc) di C. subdistichus gr. che è stato posto al di sopra dell’estinzione di E. formosa (Chapter 3). L'indagine morfometrica eseguita su questo gruppo ha fornito informazioni chiave sulla sensibilità di Clausicoccus ai cambiamenti paleoambientali avvenuti alle basse-medie latitudini e ha permesso di condurre un’indagine approfondita riguardo alle due specie appartenenti a questo gruppo, C. subdistichus e C. fenestratus (Capitolo 6). L'aumento dell'abbondanza e delle dimensioni di Clausicoccus è stato probabilmente determinato e favorito da elevate concentrazioni di nutrienti e da un'eccessiva saturazione di [CO32-] nell'acqua di mare. Infine, nel Capitolo 5, è stata eseguita un'analisi sullo stato di preservazione dell’associazione durante le fasi principali di questa transizione. Con l'aiuto del SEM sono stati confrontati due sedimenti a diversa preservazione (Site U1411 e 1209) per ricostruire le variazioni preservazionali. Al Site 1209, la diagenesi influisce in maniera grave sull’associazione, impedendo un’interpretazione paleoecologica. Nonostante questo, per la maggior parte della sezione, la diagenesi non ha alterato il segnale isotopico, che conserva le principali caratteristiche geochimiche dell'evento. Le biostratigrafiche chiave, forme resistenti alla dissoluzione, non sono state cancellate dai processi diagenetici e hanno quindi permesso di fornire un modello di età accurato.Today’s icehouse climate, characterized by two glaciated poles, is the result of gradual cooling over tens of millions of years. In the southern hemisphere, no undoubtable evidence for permanent ice on Antarctica existed until 34 Ma, when ice rafted detritus were first deposited on the surrounded sediments. From that time, known as the Eocene-Oligocene transition (E/O), the magnitude of the Antarctic ice sheet has increased unevenly toward the present. This transition also documented main reorganisation of marine and terrestrial ecosystems and paved the way to the establishment of the modern thermohaline circulation. In this context, this Ph.D. project focuses on the ecological, biostratigraphic, morphometric and preservation response of calcareous nannofossils in different sediments retrieved from the Pacific (IODP Site U1509; ODP Site U1209), Indian (ODP Site 756) and Atlantic oceans (IODP Site U1411). The main aim is to add a piece of information on the timing, modes, and magnitude of their response to sea-surface water changes related to the expansion of the Antarctic ice-sheet. Our study indicates shifts and changes within the nannoplankton community at the E-O transition, closely coupled to major isotopic excursions. Throughout the study interval, calcareous nannofossils have responded quite synchronously to glacial expansion, recording a major turnover in the assemblage from a warm-oligotrophic community, that characterized the late Priabonian to a cold eutrophic in the early Rupelian. This major turnover appears to have been triggered by a combination of decreasing temperature and increasing nutrients (Chapter 2 and Chapter 4). The high-resolution dataset also provides new potential biohorizons that can be integrated with available mid-low latitude biozonations allowing for highly refined comparison between mid-low and high latitudes (Chapter 3). Among the investigated taxa, Clausicoccus subdistichus gr. has proven to be an extraordinary biostratigraphic and paleoenvironmental proxy for this crucial climatic phase. The acme of this informal taxonomic group is present and easily recognizable at all the studied sites, even in extremely poorly preserved sediments (e.g., ODP Site 1209). The base common (Bc) of this acme represents the best nannofossil bioevent to approximate the E-O boundary (EOB), while the highest abundance values correlate with the Earliest Oligocene Glacial Maximum - EOGM. In addition, we clarify the relative ranking between the Top common and continuous of C. subdistichus gr. versus the Top of Ericsonia formosa, with the latter predating the former (Chapter 3). The morphometric investigation performed on this group provide key information on its sensitivity to paleoenvironmental changes across different latitudes and basins and enabled us to investigate in more detailed the two species ascribed to this group, i.e. C. subdistichus and C. fenestratus (Chapter 6). The increase in abundance and size of C. subdistichus gr. is likely favored by high nutrient concentrations and an oversaturation of [CO32- ] in the sea surface water across the E-O. Finally, a preservational variation of the nannofossil assemblages across the EOT is the case study of Chapter 5. We described and compared, with the aid of the SEM, the exceptional well preserved sediments at Site U1411 with the poorly preserved of Site 1209, in order to describe the wide spectrum of variation observed across the E/O. A first result is that at Site 1209, diagenesis has severely affected calcareous nannofossil assemblages, preventing any paleoecological interpretation. Despite this, for most of the section, diagenesis did not alter the primary bulk isotopic signal which still retains the main geochemical features of the event, and it has been possible to construct an accurate age model because the biostratigraphic index species are solution-resistant forms

Hall drift in the crust of neutron stars - necessary for radio pulsar activity?

The radio pulsar models based on the existence of an inner accelerating gap located above the polar cap rely on the existence of a small scale, strong surface magnetic field $B_s$. This field exceeds the dipolar field $B_d$, responsible for the braking of the pulsar rotation, by at least one order of magnitude. Neither magnetospheric currents nor small scale field components generated during neutron star's birth can provide such field structures in old pulsars. While the former are too weak to create $B_s \gtrsim 5\times 10^{13}$G$\;\gg B_d$, the ohmic decay time of the latter is much shorter than $10^6$ years. We suggest that a large amount of magnetic energy is stored in a toroidal field component that is confined in deeper layers of the crust, where the ohmic decay time exceeds $10^7$ years. This toroidal field may be created by various processes acting early in a neutron star's life. The Hall drift is a non-linear mechanism that, due to the coupling between different components and scales, may be able to create the demanded strong, small scale, magnetic spots. Taking into account both realistic crustal microphysics and a minimal cooling scenario, we show that, in axial symmetry, these field structures are created on a Hall time scale of $10^3$-$10^4$ years. These magnetic spots can be long-lived, thereby fulfilling the pre-conditions for the appearance of the radio pulsar activity. Such magnetic structures created by the Hall drift are not static, and dynamical variations on the Hall time scale are expected in the polar cap region.Comment: 4 pages, 5 figures, contribution to the ERPM conferences, Zielona Gora, April 201

Mechanisms of visual feature binding

Visual feature binding is the method by which coherent objects and scenes are perceived. Advances in the science of perception have indicated that visual features such as colour, motion, and orientation are to some extent, processed separately in primate early visual cortex. However, the mechanism by which these features are integrated remains unclear. Phenomenologically, the process of binding features to form objects appears to be an efficient and automatic process. Some research also shows a high temporal resolution for binding features together, in addition to populations of neurons that jointly code for features. However, dominant theories of feature binding and the majority of the binding literature indicate that the feature binding process is severely limited by a relatively low temporal resolution, especially when compared to other perceptual properties such as feature detection. To identify and resolve the discrepancy in the feature binding literature, I investigate the feature binding process and its inter-relationship with perceptual surface segregation. Surface segregation has been postulated as the method by which features can be rapidly bound together, giving them impression of a high temporal resolution. In Chapter 2, displays are used that alternate between two arrays of differently coloured, oppositely moving dots. The alternation frequency is modified in order to gauge the temporal resolution of binding. This is combined with surface segregation cues such as coherent motion, consistency of dot configuration, and colour. In Chapter 3, coloured, oriented gratings are used to investigate colour-orientation binding. Angular separation, spatial and temporal coincidence, and stimulus presentation duration are varied. Across these experiments, a number of these surface segregation cues are manipulated in order to measure the corresponding effects on feature binding, perceptual interpretation of the stimulus, and its neural representation. The results of the psychophysical experiments indicate that feature binding, surface segregation, and temporal integration are inextricably linked. These findings are reinforced by data gathered through functional magnetic resonance imaging (fMRI) of human subjects. Both surface segregation and feature pairs were found to modulate neural activity in early visual cortex, providing evidence that similar neural substrates are recruited for both feature binding and surface segregation. Overall, the two complementary sets of experiments using stimulus conjunctions of colour-motion and colour-orientation stimuli provide converging evidence and insight into the dynamics of the underlying binding mechanisms. A discussion of the implications of the research follows, concluding that rapidly formed surface representations can be maintained across presentation intervals by temporal integration. Attentional selection of one feature (e.g. orientation) can then be used to boost the response to the paired feature (colour) in order to identify and extract the correct feature pairing. Based on the known properties of the visual system, several potential neural mechanisms are proposed that are consistent with both the psychophysical and neural data, in addition to suggested future directions for the study of visual feature binding

Simulation of an SP8T 18 GHz RF Switch Using SMT PIN Diodes

Radio frequency (RF) and microwave switches are widely used in several different applications including radar, measurement systems, telecommunications, and other areas. An RF switch can control a radar’s transmit vs. receive mode, select the operating band, or direct an RF signal to different paths. In this study, a single pole eight throw (SP8T) switch using only Surface Mount (SMT) components is designed and simulated in Keysight’s Advanced Design System (ADS). Single pole eight throw is defined as one input and eight possible outputs. A star network configuration with series-shunt PIN diode switches is used to create the 8-way RF switch. There are other commercially available SP8T switches from MACOM, Skyworks, Analog Devices, and other vendors that operate around this bandwidth. However, this design uses SMT components and series-shunt diode configurations to create a device in the GHz range and power handling in the high 20 to 30 dBm range. This study modeled components in ADS, including the PIN diodes and the bias tees. The project also analyzed multiple layouts, finalizing the optimal design to meet specifications. The insertion loss, bandwidth, isolation, return loss, power handling, and switching speed are analyzed in the final design. Key specifications for this design are determined by comparing to other commercially available SP4T and SP8T switches from MACOM, Skyworks, Analog Devices, and other vendors, as well as developing an operational switch over the 2-18 GHz bandwidth. Additional specifications include limiting insertion loss to 2.0 dB maximum and maximizing isolation to 30 dB minimum. Switching speed and power handling specifications are also set to 20 ns and 23 dBm, respectively. Future projects will work on design fabrication and improvements to the manufactured switch