The role of the vertebrate retina in early vision is generally described by the efficient coding hypothesis, which predicts that the retina reduces the redundancy inherent in natural scenes by discarding spatiotemporal correlations while preserving stimulus information. It is unclear, however, whether the predicted decorrelation and redundancy reduction in the activity of ganglion cells, the retina's output neurons, hold under gaze shifts, which dominate the dynamics of the natural visual input. We show here that species-specific gaze patterns in natural stimuli can drive correlated spiking responses both in and across distinct types of ganglion cells in marmoset as well as mouse retina.
View Article and Find Full Text PDFSpatially nonlinear stimulus integration by retinal ganglion cells lies at the heart of various computations performed by the retina. It arises from the nonlinear transmission of signals that ganglion cells receive from bipolar cells, which thereby constitute functional subunits within a ganglion cell's receptive field. Inferring these subunits from recorded ganglion cell activity promises a new avenue for studying the functional architecture of the retina.
View Article and Find Full Text PDFAn ultimate goal in retina science is to understand how the neural circuit of the retina processes natural visual scenes. Yet most studies in laboratories have long been performed with simple, artificial visual stimuli such as full-field illumination, spots of light, or gratings. The underlying assumption is that the features of the retina thus identified carry over to the more complex scenario of natural scenes.
View Article and Find Full Text PDFThe retina dissects the visual scene into parallel information channels, which extract specific visual features through nonlinear processing. The first nonlinear stage is typically considered to occur at the output of bipolar cells, resulting from nonlinear transmitter release from synaptic terminals. In contrast, we show here that bipolar cells themselves can act as nonlinear processing elements at the level of their somatic membrane potential.
View Article and Find Full Text PDFLi commented that our report claims that methods reported thus far cannot enable the production of high-purity corundum with surface areas greater than 100 m g, and that our obtained material could be porous aggregates rather than nanoparticles. We disagree with both of these suggestions.
View Article and Find Full Text PDFIn its nanoparticulate form, corundum (α-AlO) could lead to several applications. However, its production into nanoparticles (NPs) is greatly hampered by the high activation energy barrier for its formation from cubic close-packed oxides and the sporadic nature of its nucleation. We report a simple synthesis of nanometer-sized α-AlO (particle diameter ~13 nm, surface areas ~140 m g) by the mechanochemical dehydration of boehmite (γ-AlOOH) at room temperature.
View Article and Find Full Text PDFSupported catalysts are among the most important classes of catalysts. They are typically prepared by wet-chemical methods, such as impregnation or co-precipitation. Here we disclose that dry ball milling of macroscopic metal powder in the presence of a support oxide leads in many cases to supported catalysts with particles in the nanometer size range.
View Article and Find Full Text PDFObjective: It has been suggested that the mechanism behind cardiac troponin elevation after strenuous exercise is passage through a cell membrane with changed permeability rather than myocardial cell death. We hypothesised that an increase of cardiac specific myosin heavy chain-alpha (MHC-α; 224 kDa compared with cardiac troponin T's (cTnT) 37 kDa) could hardly be explained by passage through a cell membrane.
Methods: Blood samples were collected from 56 athletes (15 female, age 42.
Single chains of metal atoms are expected to be perfect one-dimensional nanowires in nanotechnology, due to their quantum nature including tunable electronic or spin coupling strengths. However, it is still rather difficult to fabricate such nanowires with metallic atoms under directional and separation control. Here, we succeeded in building higher-order single diamondoid-chains from the lower-order chains using a chemically well-controlled approach that employs diamondoids on metal surfaces.
View Article and Find Full Text PDFNeurons in sensory systems often pool inputs over arrays of presynaptic cells, giving rise to functional subunits inside a neuron's receptive field. The organization of these subunits provides a signature of the neuron's presynaptic functional connectivity and determines how the neuron integrates sensory stimuli. Here we introduce the method of spike-triggered non-negative matrix factorization for detecting the layout of subunits within a neuron's receptive field.
View Article and Find Full Text PDFBackground: While overall physical activity is clearly associated with a better short-term and long-term health, prolonged strenuous physical activity may result in a rise in acute levels of blood-biomarkers used in clinical practice for diagnosis of various conditions or diseases. In this study, we explored the acute effects of a full Ironman-distance triathlon on biomarkers related to heart-, liver-, kidney- and skeletal muscle damage immediately post-race and after one week's rest. We also examined if sex, age, finishing time and body composition influenced the post-race values of the biomarkers.
View Article and Find Full Text PDFBiochemical changes after strenuous exercise - data from the Kalmar Ironman Strenuous and prolonged exercise like marathon, ultra running and triathlon can lead to changes in biomarkers of cardiac, muscle and kidney functional damage. We present the data of 30 (15 men, 15 women) participants of the Kalmar Ironman 2015. Pre-race electrocardiograms and echocardiograms showed a high frequency of abnormalities.
View Article and Find Full Text PDFWhen subjects monitor a single location, visual target detection depends on the pre-target phase of an ∼8 Hz brain rhythm. When multiple locations are monitored, performance decrements suggest a division of the 8 Hz rhythm over the number of locations, indicating that different locations are sequentially sampled. Indeed, when subjects monitor two locations, performance benefits alternate at a 4 Hz rhythm.
View Article and Find Full Text PDFBackground: Reduced cognitive performance and high prevalence of depression have been reported in patients with congestive heart failure (CHF) and severe left ventricular dysfunction. However, effects of contemporary device therapy on cognitive performance and depression symptoms have not been studied thoroughly.
Methods: Seventy-four consecutive CHF patients-45 receiving a biventricular defibrillator (CRT-D) and 29 receiving an implantable single or dual-chamber defibrillator (ICD) as a control group-were enrolled in this investigator-initiated, prospective, controlled, and investigator-blinded study.
Dronedarone is a new antiarrhythmic drug for patients with nonpermanent atrial fibrillation (AF). A relatively consistent finding in all trials studying dronedarone was a moderate but significant elevation of serum creatinine. Since dronedarone competes for the same organic cation transporter in the distal renal tubule with creatinine, serum creatinine and its derived estimated glomerular filtration rate might not reflect true renal function in patients on dronedarone.
View Article and Find Full Text PDFMental body representations are flexible and depend on sensory signals from the body and its surrounding. Clinical observations in amputees, paraplegics and brain-damaged patients suggest a vestibular contribution to the body schema, but studies using well-controlled psychophysical procedures are still lacking. In Experiment 1, we used a tactile distance comparison task between two body segments (hand and forehead).
View Article and Find Full Text PDF1,4-Butanediol (BDO) is an important commodity chemical used to manufacture over 2.5 million tons annually of valuable polymers, and it is currently produced exclusively through feedstocks derived from oil and natural gas. Herein we report what are to our knowledge the first direct biocatalytic routes to BDO from renewable carbohydrate feedstocks, leading to a strain of Escherichia coli capable of producing 18 g l(-1) of this highly reduced, non-natural chemical.
View Article and Find Full Text PDFWith increasing timeline pressures to get therapeutic and vaccine candidates into the clinic, resource intensive approaches such as the use of shake flasks and bench-top bioreactors may limit the design space for experimentation to yield highly productive processes. The need to conduct large numbers of experiments has resulted in the use of miniaturized high-throughput (HT) technology for process development. One such high-throughput system is the SimCell platform, a robotically driven, cell culture bioreactor system developed by BioProcessors Corp.
View Article and Find Full Text PDFMulti-factorial experimentation is essential in understanding the link between mammalian cell culture conditions and the glycoprotein product of any biomanufacturing process. This understanding is increasingly demanded as bioprocess development is influenced by the Quality by Design paradigm. We have developed a system that allows hundreds of micro-bioreactors to be run in parallel under controlled conditions, enabling factorial experiments of much larger scope than is possible with traditional systems.
View Article and Find Full Text PDFPhilos Trans A Math Phys Eng Sci
November 2005
Experimental data associated with plastic deformations indicate that the temperature is less than that predicted from dissipation based on plastic work. To obtain reasonable correlation between theoretical and experimental results, the plastic work is often multiplied by a constant beta. This paper provides an alternative thermodynamic framework in which it is proposed that there is an additional internal energy associated with dislocation pile-up or increase in dislocation density.
View Article and Find Full Text PDFBackground: Although surgery for the treatment of hallux valgus is frequently performed, the exact rate of deep vein thrombosis following this procedure is unknown. We performed a single-center, prospective, phlebographically controlled study to quantify the rate of venous thrombosis following operative correction of hallux valgus.
Methods: Consecutive patients undergoing chevron bunionectomy for correction of hallux valgus deformity were enrolled in the study.
The most common reasons for gynecological bleeding are pregnancy-related disorders, fibroids of the uterus, and gynecological malignancies. Transarterial embolization is an effective treatment modality for gynecological bleeding regardless of its etiology. Depending on the underlying disease, a different technique of embolization is applied.
View Article and Find Full Text PDFDespite of the diagnostic potential of conventional CT (CCT), limitations being inherent in this technology reduce its diagnostic confidence and limit clinical CT applications as 3D imaging. Helical CT (HCT) has far overcome the limitations of CCT and has become the standard CT technology. After a short overview on the technique of HCT and its advantages over CCT, the impact of HCT on the detection of disorders of the urinary organs is discussed.
View Article and Find Full Text PDFBiomacromolecules
January 2002
Gel fibers made from polyacrylonitrile (PAN) are known to elongate and contract when immersed in caustic and acidic solutions, respectively. The amount of contraction for these pH-activated fibers is 50% or greater, and the strength of these fibers is shown to be comparable to that of human muscle. Despite these attributes, the need of strong acids and bases for actuation has limited the use of PAN gel fibers as linear actuators or artificial muscles.
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