2,034 research outputs found

    Anodal tDCS and High-Frequency tRNS Targeting the Occipitotemporal Cortex Do Not Always Enhance Face Perception

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    There has been increasing interest in the utility of transcranial electrical stimulation as a tool to enhance cognitive abilities. In the domain of face perception, enhancements have been reported for both transcranial direct current stimulation (tDCS) and high-frequency transcranial random noise stimulation (tRNS) targeting the occipitotemporal cortex. In a series of two experiments, we attempted to replicate these findings for face identity perception, and extend on previous studies, to determine if similar enhancements are also observed for object and facial expression perception. In Experiment 1, using a single blind, between-subjects design in healthy volunteers (N = 53), we examined whether anodal tDCS over the occipitotemporal cortex enhanced performance on tasks involving perception of face identity, facial expression, and object stimuli, when compared to sham stimulation. We failed to replicate previous findings of enhanced performance on face and object perception, nor extend findings to facial expression perception. In Experiment 2, using a single blind, between-subjects design (N = 39), we examined the effect of high-frequency tRNS over the occipitotemporal cortex using the same three tasks employed in Experiment 1. We failed to replicate previous findings of enhanced face perception following high-frequency tRNS over the occipitotemporal cortex, relative to sham stimulation (although we used different stimulation parameters to that employed in a previous study). We also found no evidence of enhanced facial expression and object perception following high-frequency tRNS. The findings align with a growing body of studies that have failed to replicate previously reported enhancements following administration of tDCS and hint for different efficacy of, on first sight, related stimulation protocols. Future studies should explore the foundation of these differential effects in greater detail

    The extension problem for partial Boolean structures in Quantum Mechanics

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    Alternative partial Boolean structures, implicit in the discussion of classical representability of sets of quantum mechanical predictions, are characterized, with definite general conclusions on the equivalence of the approaches going back to Bell and Kochen-Specker. An algebraic approach is presented, allowing for a discussion of partial classical extension, amounting to reduction of the number of contexts, classical representability arising as a special case. As a result, known techniques are generalized and some of the associated computational difficulties overcome. The implications on the discussion of Boole-Bell inequalities are indicated.Comment: A number of misprints have been corrected and some terminology changed in order to avoid possible ambiguitie

    Mutagenesis of hepatitis C virus E1 protein affects its membrane-permeabilizing activity

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    The E1 glycoprotein of hepatitis C virus is a transmembrane glycoprotein with a C-terminal anchor domain. When expressed inEscherichia coli, E1 induces a change in membrane permeability that is toxic to the bacterial cell. The C-terminal hydrophobic region (aa 331–383) of E1 is mainly responsible for membrane association and for inducing changes in membrane permeability. These observed changes are similar to those produced inE. coliby influenza virus M2, human immunodeficiency virus gp41 and poliovirus 3AB proteins, whose hydrophobic domains are thought to cause pore formation in biological membranes. To further characterize the activity of E1 at a molecular level, the membrane-permeabilizing ability of a second internal hydrophobic region (aa 262–291) was examined by expressing different deletion mutants of E1 in anE. colisystem that is widely used for analysing membrane-active proteins from other animal viruses. Moreover, highly conserved amino acids in the C-terminal hydrophobic region were mutated to identify residues that are critical for inducing changes in membrane permeability. Analysis of cell growth curves of recombinant cultures and membrane-permeability assays revealed that synthesis of this fragment increased the flux of small compounds through the membrane and caused progressive cell lysis, suggesting that this domain has membrane-active properties. Furthermore, analysis of C-terminal mutants indicated that the conserved amino acids Arg339, Trp368and Lys370play a critical role in protein function, as both cell lysis and changes in membrane permeability induced by the wild-type clone could be blocked by substitutions in these positions

    Internal Maxillary Artery-Middle Cerebral Artery Bypass: Infratemporal Approach for Subcranial-Intracranial (SC-IC) Bypass

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    BACKGROUND:Internal maxillary artery (IMax)-middle cerebral artery (MCA) bypass has been recently described as an alternative to cervical extracranial-intracranial bypass. This technique uses a keyhole craniectomy in the temporal fossa that requires a technically challenging end-to-side anastomosis.OBJECTIVE:To describe a lateral subtemporal craniectomy of the middle cranial fossa floor to facilitate wide exposure of the IMax to facilitate bypass.METHODS:Orbitozygomatic osteotomy is used followed by frontotemporal craniotomy and subsequently laterotemporal fossa craniectomy, reaching its medial border at a virtual line connecting the foramen rotundum and foramen ovale. The IMax was identified by using established anatomic landmarks, neuronavigation, and micro Doppler probe (Mizuho Inc. Tokyo, Japan). Additionally, we studied the approach in a cadaveric specimen in preparation for microsurgical bypass.RESULTS:There were 4 cases in which the technique was used. One bypass was performed for flow augmentation in a hypoperfused hemisphere. The other 3 were performed as part of treatment paradigms for giant middle cerebral artery aneurysms. Vein grafts were used in all patients. The proximal anastomosis was performed in an end-to-side fashion in 1 patient and end-to-end in 3 patients. Intraoperative graft flow measured with the Transonic flow probe ranged from 20 to 60 mL/min. Postoperative angiography demonstrated good filling of the graft with robust distal flow in all cases. All patients tolerated the procedure well.CONCLUSION:IMax to middle cerebral artery subcranial-intracranial bypass is safe and efficacious. The laterotemporal fossa craniectomy technique resulted in reliable identification and wide exposure of the IMax, facilitating the proximal anastomosis

    WAx: an integrated conceptual framework for the analysis of cyber-socio-technical systems

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    Modern work domains are constituted by an intertwined set of social and technical actors with different, often conflicting, functional purposes. These agents act jointly to ensure system's functioning under both expected and unexpected working conditions. Considering the increasing digitalization and automation of work processes, socio-technical systems are progressively including interconnected cyber technical artefacts, thus becoming cyber-socio-technical systems (CSTSs). Adopting a natural science perspective, this paper aims to explore knowledge creation and knowledge conversion within CSTSs, as rooted in an in-depth analysis of work practices and work contexts. The paper proposes a conceptual framework which unveils the relationships between different work representations, i.e. relying on Work-As-Imagined, Work-As-Done, Work-As-Disclosed, Work-As-Observed, intended as knowledge entities generated by different agents, i.e. sharp-end operators, blunt-end operators, and analysts. The recursive and fractal nature of the proposed WAx (Work-As-x) framework ensures its adaptability for different granularity levels of analysis, fostering the understanding, modeling, and analysis of work practices, while abandoning reductionist and over-simplistic approaches

    Park\u27s Tribolium Competition Experiments: A Non-equilibrium Species Coexistence Hypothesis

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    1. In this journal 35 years ago, P. H. Leslie, T. Park and D. B. Mertz reported competitive exclusion data for two Tribolium species. It is less well-known that they also reported \u27difficult to interpret\u27 coexistence data. We suggest that the species exclusion and the species coexistence are consequences of a stable coexistence two-cycle in the presence of two stable competitive exclusion equilibria. 2. A stage-structured insect population model for two interacting species forecasts that as interspecific interaction is increased there occurs a sequence of dynamic changes (bifurcations) in which the classic Lotka-Volterra-type scenario with two stable competitive exclusion equilibria is altered abruptly to a novel scenario with three locally stable entities; namely, two competitive exclusion equilibria and a stable coexistence cycle. This scenario is novel in that it predicts the competitive coexistence of two nearly identical species on a single limiting resource and does so under circumstances of increased interspecific competition. This prediction is in contradiction to classical tenets of competition theory

    Use of the frozen elephant trunk technique for type B aortic dissection and aberrant right subclavian artery: an anatomic repair of the “arteria lusoria”

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    Retrograde extension into the aortic arch occurs in 16.5% of patients with type B aortic dissection (TBAD) (1). This cohort of patients may be eligible for a radical repair using the frozen elephant trunk (FET) technique. The combination of surgical replacement of the aortic arch and deployment of the stent graft allows complete exclusion of the false lumen in aortic dissections. In the case of aneurysm or residual dissection, patients undergoing FET are ready for subsequent endovascular or surgical treatment (2)

    A proposal for an evidence-based model of the screening for the colorectal carcinoma in an Italian setting

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    Introduction. The aim of this paper is to improve the feasibility perception of policymakers, health care workers and target population about the cost-effectiveness of the implementation of colorectal screening as Public Health strategy. Methods. Retrospective study by application of a three-step model designed for a local setting in Sicily (Palermo and its Province) in order to distribute Fecal Occult Blood Tests (FOBTs), offer colonoscopy and surgery, by district allocation of pharmacies, public digestive endoscopic centres and oncologic and general surgery units. Mean adherence to consolidated colorectal screening programs in Italy was applied in order to evaluate the feasibility of an operative model in our area. Results. Applying the model to the target population (269,368 individuals of both sexes), it can be expected a mean percentage of 79% delivered invitation and a mean participation rate of 46.3% accounting for a total of 213,070 invited individuals and 98,651 participating in the first round of the program. Furthermore, considering the national mean of 6% positive FOBT, 82% of colonscopy adhesion and 7% CRC detection rate, it can be scheduled a burden for health care structures involved in the program accounting for 49,325 FOBTs, 2,338 colonscopies and 141 surgeries for each year. Discussion. This work demonstrates the feasibility of a colorectal screening project in our area, showing a sustainable impact for local health care involved structures. Furthermore, this program may be spread as an applicative model to other areas, adapting the project to the needs of the local setting in which the colorectal screening will be organized

    Fluorescein for resection of high-grade gliomas: A safety study control in a single center and review of the literature

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    Background: The importance of a complete resection of high-grade gliomas (HGGs) has been highlighted in scientific literature, in order to limit tumor recurrence and above all to improve disease-free survival rates. Several fluorescent biomarkers have been tested to improve intraoperative identification of residual tumor; 5-aminolevulinic acid (5-ALA) and fluorescein sodium (FS) are now starting to play a central role in glioma surgery. We performed a retrospective analysis on 47 patients operated for HGGs. Here we report our preliminary data. Methods: Data of 47 consecutive patients with HGG have been collected in our study (25 males, 22 females; mean age: 60.3 years, range: 27-86 years). Fluorescein (5 mg/kg of body weight) was injected intravenously right after the induction of general anesthesia. A YELLOW 560 filter was used on an OPMI Pentero 900 microscope (Carl Zeiss Meditec, Oberkochen, Germany) to complete a microsurgical tumor removal. Glioma resection and quality of life were evaluated preoperative and postoperatively. Results: Gross total resection (GTR) was achieved in 53.2% (n = 25) of patients. A subtotal resection (STR) (>95%) was achieved in 29.8% (n = 14), while a partial resection (PR) (<95%) was obtained in 17% (n = 8) of patients. Overall, in 83% (n = 39) of patients who underwent fluorescence-guided surgery the resection rate achieved was >95%. No adverse effects correlated to fluorescein have been recorded. Conclusion: Fluorescein seems to be safe and effective in the resection of HGGs, allowing a high rate of gross total removal of contrast enhanced areas

    Canal switch and re-entry phenomenon in benign paroxysmal positional vertigo: difference between immediate and delayed occurrence

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    Studio prospettico ideato per la valutazione delle differenze tra la conversione canalare o il rientro degli otoliti nei canali semicircolari successivo alle manovre terapeutiche nei pazienti affetti da VPPB. Sono stati valutati 196 pazienti affetti da VPPB, 127 dei quali corrispondevano ai criteri di inclusione. L’età media dei pazienti era di 54.74 anni. Il canale orizzontale è stato coinvolto in 30 casi e il canale posteriore in 97 pazienti. I pazienti con sordità neurosensoriale presentavano forme ricorrenti di VPPB, rispetto a quelli con udito normale. L’immediato rientro canalare è stato diagnosticato in 3 pazienti con VPPB del canale laterale, tutti con nistagmo geotropo. 7 pazienti con VPPB del canale posteriore hanno presentato un rientro canalare immediato e 5 la forma ritardata. I pazienti con rientro canalare ritardato avevano precedentemente subito più di 2 manovre di riposizionamento. Il rientro canalare non è risultato connesso al tipo di manovra eseguita. Il tempo di attesa tra l’esecuzione della manovra liberatoria e il test di verifica si è rivelato importante ai fini del rientro canalare immediato. La recidiva della BPPV dopo un mese dalle manovre liberatorie si è riscontrata in 20 pazienti ed è stata più frequente in quei pazienti che hanno avuto un fenomeno di rientro canalare. La conversione canalare ed il fenomeno del rientro canalare rappresentano delle entità cliniche che devono essere considerate dal medico che tratta le VPPB. Appare importante distinguere un rientro da un fallimento della manovra in caso di forme immediate, o da una recidiva di patologia in caso di forme ritardate. L’esecuzione del test di verifica del successo terapeutico dopo manovre di riposizionamento deve avere un distacco temporale sufficientemente ampio al fine di evitare il reflusso immediato di otoliti nei canali.This prospective study was designed to evaluate the differences between immediate and delayed canal re-entry of otoliths after therapeutic manoeuvres in patients with benign paroxysmal positional vertigo (BPPV). A total of 196 patients with BPPV were visited and 127 matched our inclusion criteria. The mean age was 54.74 years. The horizontal semicircular canal (HSC) was involved in 30 cases and the posterior semicircular canal (PSC) in 97 patients. Patients with hearing loss in the ear affected by BPPV have a more recurrent form, compared to those with normal hearing. An immediate canal re-entry was recorded in 3 patients with HSC BPPV, all with geotropic nystagmus. In 7 patients with PSC BPPV, the immediate canal re-entry was detected and the delayed form was noted in 5 patients. The patients with the delayed canal re-entry underwent more than 2 previous manoeuvres. The canal re-entry was not related to the manoeuvre performed. The timing of the Dix-Hallpike test to verify the resolution of the BPPV had a significant role in immediate canal re-entry. A recurrence in the follow-up at least one month after treatment was recorded in 20 patients and was more frequent in patients that had canal re-entry. The canal re-entry or canal switch is a clinical entity that should be kept in mind of the neurotologist when approaching BPPV patients. It is important to distinguish it from recurrence when delayed and from manoeuvre failure when immediate. The timing of manoeuvre performing, in particular the final verification test after therapeutic sessions, is important to prevent the immediate reflux of particles into canals
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