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A tiny macroscope to look into complex behavior
摘要： A macroscope mounted on the head of a freely moving transgenic rat can help shine light on complex behaviors. A macroscope is a microscopy device able to image at the mesoscopic scale, typically from hundreds of micrometers to centimeters. Such devices have been used to record neural activity in the brains of behaving rodents, mostly by measuring intracellular calcium dynamics in neurons. Usually the head of the animal needs to be restrained to ensure that the brain position remains stable relative to the imaging system, which limits the range of behaviors that can be studied. Alternatively, the use of miniaturized head-mounted microscopes allows for functional imaging in freely moving animals, which introduces the possibility of studying more sophisticated behaviors. However, most head-mounted microscopes can image only a relatively small field of view—typically less than 1 mm2, which is not compatible with the recording of neural activity across multiple brain regions. Also, these systems often cannot correct for image contamination caused by changes in blood flow due to neural activity, a phenomenon known as hemodynamic response. To overcome these limitations, David Tank and his team at Princeton University have developed cScope, a head-mounted macroscope able to image a field of view larger than 30 mm2 at the mesoscopic scale, without the need for animal head restraint. This is a low-cost 3D-printed plastic device equipped with two independent illumination sources, one for fluorescence imaging and one for hemodynamic response correction. The name cScope stands for “cortical macroscope,” underlining the ability to image various regions of the neocortical surface simultaneously, including sensory and motor regions as well as association regions. The researchers also developed new strains of transgenic rats expressing the genetically encoded calcium indicator GCaMP6f in a large proportion of neurons in the brain, by using pan-neuronal enhancers known to drive expression throughout the nervous system. In rats, fluorescent reporters are usually delivered by viral injection, which labels only a small region of tissue; therefore, the generation of transgenic rats expressing GCaMP6f in the neocortex, hippocampus, cerebellum, and other regions allows scientists to make the most of the large field of view available with the cScope. The team demonstrated the use of cScope to image spatiotemporal activity patterns across multiple brain areas, by imaging neuronal calcium dynamics in rats performing an evidence-based decision-making task. In this task each rat was exposed to random sequences of light flashes from its right and left sides, and it received a reward when it oriented toward the side with more flashes. The researchers observed that stimulus identity during cue presentation could be inferred from the activity in visual cortical regions, while the rat’s behavioral choice could be predicted on the basis of the activity in parietal cortical regions. These results confirm that complex behaviors recruit multiple brain regions, and that cScope can help scientists map activity in distant brain areas during behavioral tests. The combination of cScope and transgenic rats expressing the GCaMP6f calcium sensor expands the application of head-mounted microscopes into the mesoscopic scale and enables studies of global neural activity during a range of natural behaviors, including navigation, sleep, and social interactions. The authors of the study anticipate that cScope could also be used to image hemodynamic response, in addition to fluorescent reporters, in the brains of various animal models, including wild-type rats and even larger animals such as marmosets.
关键词： GCaMP6f,macroscope,hemodynamic response,transgenic rats,neural activity
更新于2025-09-04 15:30:14
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Optimization and modeling of UV-TiO <sub/>2</sub> mediated photocatalytic degradation of golden yellow dye through response surface methodology
摘要： In this article, heterogeneous photocatalysis of golden yellow (GY) dye by Evonik p25 titanium dioxide (PTD) and UV radiations was optimized by using central composite design of response surface methodology. The GY dye photocatalysis was expressed as the function of amount of PTD loading (X1), GY dye initial concentration (X2), and UV irradiance intensity (X3). The optimization of degradation conditions was done by measuring two different responses, that is, color removal (Y1) and chemical oxygen demand removal (Y2). The effect of X1, X2, and X3 were studied in the range 0.5–1.5 g/L, 15–35 W/m2, and 10–30 mg/L, respectively. The quadratic model was suggested for Y1 and Y2. The numerical optimization of results was done via Design Expert software. The predictive results obtained were verified by performing actual experiments. The photodegradation kinetics, total organic carbon disappearance, effect of inorganic salts, and H2O2 concentration on GY dye photodegradation were also studied.
关键词： Titanium dioxide,Heterogeneous photocatalysis,Central composite design,Optimization,Golden yellow dye,Response surface methodology
更新于2025-09-04 15:30:14
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Diurnal Variation in Intraocular Pressure Measured by Ocular Response Analyzer in Korean Patients with Normal Tension Glaucoma
摘要： Purpose: To analyze the diurnal change in intraocular pressure (IOP) and corneal biomechanical properties measured using the Ocular Response Analyzer (ORA; Reichert Inc., Depew, NY, USA) in Korean patients with normal tension glaucoma (NTG) patients. Methods: Intraocular pressure (Goldmann applanation tonometer IOP [GAT IOP], Goldmann-correlated IOP [IOPg], corneal-compensated IOP [IOPcc]) and corneal hysteresis (CH), corneal resistance factor (CRF) and central corneal thickness (CCT) were measured in 21 eye of NTG patients (12 males, 9 female) at 3 hour intervals for 48 hours using ORA. We recorded the time of each parameter that showed the lowest and the highest values of during the 48 hour testing period (Day 1 and Day 2) and evaluated the change of diurnal variation using Repeated measures analysis of variance (Re-ANOVA). Results: Peak IOP measured with GAT and ORA occurred at 6 AM-9 AM, 3 PM-6 PM and the trough IOP at 9 PM-12 AM during the 48 hour period. CCT, GAT IOP, IOPcc and IOPg measurements showed statistically significant variations (p<0.05). CH and CRF variations were not statistically significant (p>0.05). Conclusions: In Korean NTG patients, IOP exhibits significant diurnal variation, with higher values during the dawn and afternoon and lower values before retiring. Clinically, measurements of IOP performed in the afternoon could aid in the detection of relatively elevated IOP.
关键词： Diurnal variation,Ocular response analyzer,Intraocular pressure,Biomechanical properties
更新于2025-09-04 15:30:14
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Unit Circle Rectification of the Minimum Variance Distortionless Response Beamformer
摘要： The sample matrix inversion (SMI) beamformer implements Capon’s minimum variance distortionless (MVDR) beamforming using the sample covariance matrix (SCM). In a snapshot limited environment, the SCM is poorly conditioned resulting in a suboptimal performance from the SMI beamformer. Imposing structural constraints on the SCM estimate to satisfy known theoretical properties of the ensemble MVDR beamformer mitigates the impact of limited snapshots on the SMI beamformer performance. Toeplitz recti?cation and bounding the norm of weight vector are common approaches for such constraints. This paper proposes the unit circle recti?cation technique which constrains the SMI beamformer to satisfy a property of the ensemble MVDR beamformer: for narrowband planewave beamforming on a uniform linear array, the zeros of the MVDR weight array polynomial must fall on the unit circle. Numerical simulations show that the resulting unit circle MVDR (UC MVDR) beamformer frequently improves the suppression of both discrete interferers and white background noise compared to the classic SMI beamformer. Moreover, the UC MVDR beamformer is shown to suppress discrete interferers better than the MVDR beamformer diagonally loaded to maximize the signal-to-interference-plus-noise ratio.
关键词： unit circle,Capon beamformer,array polynomial,minimum variance distortionless response (MVDR),Adaptive beamformer (ABF)
更新于2025-09-04 15:30:14
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Out-of-Band Response for the Coastal Zone Imager (CZI) Onboard China’s Ocean Color Satellite HY-1C: Effect on the Observation Just above the Sea Surface
摘要： The out-of-band (OOB) response is one of the key speci?cations for satellite optical sensors, which has important in?uences on quantitative remote sensing retrieval. In this paper, the effect of OOB response on the radiometric measurements made just above the sea surface is evaluated for the three broad visible bands (i.e., blue, green, and red) of the Coastal Zone Imager (CZI) onboard China’s ocean satellite HY-1C to be launched in September 2018. For the turbid coastal (Case 2) waters whose optical properties are mainly dominated by suspended sediment and colored dissolved organic material, the OOB effect can be neglected (<2%) for all three CZI visible bands. For the phytoplankton-dominated (Case 1) waters which are mainly distributed in the clear open ocean, a signi?cant (>2%) OOB effect was found in the green band over oligotrophic waters (chlorophyll a concentration ≤~0.1 mg/m3), and accordingly a model based on the CZI blue-green band ratio is proposed to correct this effect. The OOB in?uence on the CZI ocean color retrieval is discussed. This research highlights the importance of the comprehensive pre-launch radiometric characterization and the OOB effect correction for the broad band space-borne sensor, in order to achieve a high-quality quantitative ocean product.
关键词： out-of-band response,HY-1,Coastal Zone Imager (CZI)
更新于2025-09-04 15:30:14