Field and laboratory measurement of heart rate in a tropical limpet, Cellana grata

Heart rate of the tropical limpet Cellana grata was monitored on the shore (Cape d'Aguilar, Hong Kong) and in the laboratory using a non-invasive technique. Individual field measurements performed on inactive limpets, in a variety of thermal conditions during a diurnal low tide, showed a general increase in heart rate with increasing body temperature. This relationship was not always evident when monitoring individual responses over a diurnal low tide period, since under some circumstances, heart rate of individuals decreased with increasing the temperature of the substrate and foot. A factorial laboratory experiment showed that heart rate was faster at higher temperatures but slower in larger animals. The combined evaluation of field and laboratory data suggests that limpets in some habitats may be able to regulate their metabolic rate when resting on hot rock substrates.published_or_final_versio

Cardiac output: A central issue in patients with respiratory extracorporeal support

The iLA-activve® Novalung is a new extracorporeal device specifically designed for lung support in patients with hypercapnic and/or hypoxemic respiratory failure. To date, only low-flow applications for decompensated hypercapnic chronic obstructive pulmonary disease have been reported in the literature. Here, we briefly report three cases of iLA-activve use in patients with hypercapnic-hypoxemic acute lung failure assisted with mid-flow (up to 2.4 L/min) and different single/double venous cannulation. The main findings of our small case series were: firstly, extracorporeal blood flows over 2.0 L/min across the membrane provided clinically satisfying decarboxylation and improved oxygenation; secondly, the ratio between blood flow through the membrane and the patient's cardiac output (CO) was a major determinant for the oxygen increase. The latter could, therefore, be a useful indicator for understanding performance in the complex and multifactorial evaluation of patients with extracorporeal veno-venous lung support

A combined crystallographic and computational study on dexketoprofen trometamol dihydrate salt

Dexketoprofen trometamol is the tromethamine salt of dexketoprofen [(2S)-2-(3-benzoylphenyl)propanoic acid-2-amino-2-(hydroxymethyl)propane-1,3-diol], a nonsteroidal anti-inflammatory drug (NSAID) used for the treatment of moderate- to strong-intensity acute pain. The crystal structure of the hitherto sole known hydrate phase of dexketoprofen trometamol (DK-T_2H2O), as determined by single-crystal X-ray diffraction, is presented. The water molecules are arranged in dimers included in isolated sites and sandwiched between piles of trometamol cations. The molecular and crystal structures of DK-T_2H2O are analyzed and compared to those of the parent anhydrous crystal form DK-T_A. In both the crystal structures, all the potential H-bond donors and acceptor of the dexketoprofen and trometamol ions are engaged, and both the species crystallize in the P21 space group. However, during the DK-T_A➔DK-T_2H2O hydration process, the unique symmetry axis is not conserved, i.e., the ions are arranged in a different way with respect to the screw axis, even if the two crystal structures maintain structural blocks of DK anions and T cations. Quantum mechanical solid-state calculations provide some hints for the possible intermediate structure during the crystalline–crystalline hydration/dehydration process

Contributions from cognitive neuroscience to understanding functional mechanisms of visual search.

We argue that cognitive neuroscience can contribute not only information about the neural localization of processes underlying visual search, but also information about the functional nature of these processes. First we present an overview of recent work on whether search for form - colour conjunctions is constrained by processes involved in binding across the two dimensions. Patients with parietal lesions show a selective problem with form - colour conjunctive search relative to a more difficult search task not requiring cross-dimensional binding. This is consistent with an additional process - cross-dimensional binding - being involved in the conjunctive search task. We then review evidence from preview search using electrophysiological, brain imaging, and neuropsychological techniques suggesting preview benefits in search are not simply due to onset capture. Taken together the results highlight the value of using converging evidence from behavioural studies of normal observers and studies using neuroscientific methods. © 2006 Psychology Press Ltd

Modelling Visual Neglect: Computational Insights into Conscious Perception

Background: Visual neglect is an attentional deficit typically resulting from parietal cortex lesion and sometimes frontal lesion. Patients fail to attend to objects and events in the visual hemifield contralateral to their lesion during visual search. Methodology/Principal Finding: The aim of this work was to examine the effects of parietal and frontal lesion in an existing computational model of visual attention and search and simulate visual search behaviour under lesion conditions. We find that unilateral parietal lesion in this model leads to symptoms of visual neglect in simulated search scan paths, including an inhibition of return (IOR) deficit, while frontal lesion leads to milder neglect and to more severe deficits in IOR and perseveration in the scan path. During simulations of search under unilateral parietal lesion, the model’s extrastriate ventral stream area exhibits lower activity for stimuli in the neglected hemifield compared to that for stimuli in the normally perceived hemifield. This could represent a computational correlate of differences observed in neuroimaging for unconscious versus conscious perception following parietal lesion. Conclusions/Significance: Our results lead to the prediction, supported by effective connectivity evidence, that connections between the dorsal and ventral visual streams may be an important factor in the explanation of perceptua

Nanomaterials for the cleaning and pH adjustment of vegetable tanned leather

Leather artifacts in historical collections and archives are often contaminated by physical changes such as soiling, which alter their appearance and readability, and by chemical changes which occur on ageing and give rise to excessive proportion of acids that promote hydrolysis of collagen, eventually leading to gelatinization and loss of mechanical properties. However, both cleaning and pH adjustment of vegetable tanned leather pose a great challenge for conservators, owing to the sensitivity of these materials to the action of solvents, especially water-based formulations and alkaline chemicals. In this study the cleaning of historical leather samples was optimized by confining an oil-in-water (o/w) nanostructured fluid in a highly retentive chemical hydrogel, which allows the controlled release of the cleaning fluid on sensitive surfaces. The chemical gel exhibits optimal viscoelasticity, which facilitates its removal after the application without leaving residues on the object. Nanoparticles of calcium hydroxide and lactate, dispersed in 2-propanol, were used to adjust the pH up to the natural value of leather, preventing too high alkalinity which causes swelling of fibers and denaturation of the collagen. The treated samples were characterized using Scanning Electron Microscopy (FE SEM), controlled environment dynamic mechanical analysis (DMA-RH), and infrared spectroscopy (ATR-FTIR). The analytical assessment validated the use of tools derived from colloid and materials science for the preservation of collagen-based artifacts

Biased competition through variations in amplitude of γ-oscillations

Experiments in visual cortex have shown that the firing rate of a neuron in response to the simultaneous presentation of a preferred and non-preferred stimulus within the receptive field is intermediate between that for the two stimuli alone (stimulus competition). Attention directed to one of the stimuli drives the response towards the response induced by the attended stimulus alone (selective attention). This study shows that a simple feedforward model with fixed synaptic conductance values can reproduce these two phenomena using synchronization in the gamma-frequency range to increase the effective synaptic gain for the responses to the attended stimulus. The performance of the model is robust to changes in the parameter values. The model predicts that the phase locking between presynaptic input and output spikes increases with attention

Precisely timed oculomotor and parietal EEG activity in perceptual switching

Blinks and saccades cause transient interruptions of visual input. To investigate how such effects influence our perceptual state, we analyzed the time courses of blink and saccade rates in relation to perceptual switching in the Necker cube. Both time courses of blink and saccade rates showed peaks at different moments along the switching process. A peak in blinking rate appeared 1,000 ms prior to the switching responses. Blinks occurring around this peak were associated with subsequent switching to the preferred interpretation of the Necker cube. Saccade rates showed a peak 150 ms prior to the switching response. The direction of saccades around this peak was predictive of the perceived orientation of the Necker cube afterwards. Peak blinks were followed and peak saccades were preceded by transient parietal theta band activity indicating the changing of the perceptual interpretation. Precisely-timed blinks, therefore, can initiate perceptual switching, and precisely-timed saccades can facilitate an ongoing change of interpretation