Effect of Biomass Water Dynamics in Cosmic-Ray Neutron Sensor Observations: A Long-Term Analysis of Maize-Soybean Rotation in Nebraska.

Precise soil water content (SWC) measurement is crucial for effective water resource management. This study utilizes the Cosmic-Ray Neutron Sensor (CRNS) for area-averaged SWC measurements, emphasizing the need to consider all hydrogen sources, including time-variable plant biomass and water content. Near Mead, Nebraska, three field sites (CSP1, CSP2, and CSP3) growing a maize-soybean rotation were monitored for 5 (CSP1 and CSP2) and 13 (CSP3) years. Data collection included destructive biomass water equivalent (BWE) biweekly sampling, epithermal neutron counts, atmospheric meteorological variables, and point-scale SWC from a sparse time domain reflectometry (TDR) network (four locations and five depths). In 2023, dense gravimetric SWC surveys were collected eight (CSP1 and CSP2) and nine (CSP3) times over the growing season (April to October). The N0 parameter exhibited a linear relationship with BWE, suggesting that a straightforward vegetation correction factor may be suitable (fb). Results from the 2023 gravimetric surveys and long-term TDR data indicated a neutron count rate reduction of about 1% for every 1 kg m-2 (or mm of water) increase in BWE. This reduction factor aligns with existing shorter-term row crop studies but nearly doubles the value previously reported for forests. This long-term study contributes insights into the vegetation correction factor for CRNS, helping resolve a long-standing issue within the CRNS community.

Computational models of intrinsic motivation for curiosity and creativity.

We link Ivancovsky et al.'s novelty-seeking model (NSM) to computational models of intrinsically motivated behavior and learning. We argue that dissociating different forms of curiosity, creativity, and memory based on the involvement of distinct intrinsic motivations (e.g., surprise and novelty) is essential to empirically test the conceptual claims of the NSM.

Field Testing of Gamma-Spectroscopy Method for Soil Water Content Estimation in an Agricultural Field.

Gamma-ray spectroscopy (GRS) enables continuous estimation of soil water content (SWC) at the subfield scale with a noninvasive sensor. Hydrological applications, including hyper-resolution land surface models and precision agricultural decision making, could benefit greatly from such SWC information, but a gap exists between established theory and accurate estimation of SWC from GRS in the field. In response, we conducted a robust three-year field validation study at a well-instrumented agricultural site in Nebraska, United States. The study involved 27 gravimetric water content sampling campaigns in maize and soybean and 40K specific activity (Bq kg-1) measurements from a stationary GRS sensor. Our analysis showed that the current method for biomass water content correction is appropriate for our maize and soybean field but that the ratio of soil mass attenuation to water mass attenuation used in the theoretical equation must be adjusted to satisfactorily describe the field data. We propose a calibration equation with two free parameters: the theoretical 40K intensity in dry soil and a, which creates an "effective" mass attenuation ratio. Based on statistical analyses of our data set, we recommend calibrating the GRS sensor for SWC estimation using 10 profiles within the footprint and 5 calibration sampling campaigns to achieve a cross-validation root mean square error below 0.035 g g-1.

Surprise and novelty in the brain.

Notions of surprise and novelty have been used in various experimental and theoretical studies across multiple brain areas and species. However, 'surprise' and 'novelty' refer to different quantities in different studies, which raises concerns about whether these studies indeed relate to the same functionalities and mechanisms in the brain. Here, we address these concerns through a systematic investigation of how different aspects of surprise and novelty relate to different brain functions and physiological signals. We review recent classifications of definitions proposed for surprise and novelty along with links to experimental observations. We show that computational modeling and quantifiable definitions enable novel interpretations of previous findings and form a foundation for future theoretical and experimental studies.

Modulation of working memory duration by synaptic and astrocytic mechanisms.

Short-term synaptic plasticity and modulations of the presynaptic vesicle release rate are key components of many working memory models. At the same time, an increasing number of studies suggests a potential role of astrocytes in modulating higher cognitive function such as WM through their influence on synaptic transmission. Which influence astrocytic signaling could have on the stability and duration of WM representations, however, is still unclear. Here, we introduce a slow, activity-dependent astrocytic regulation of the presynaptic release probability in a synaptic attractor model of WM. We compare and analyze simulations of a simple WM protocol in firing rate and spiking networks with and without astrocytic regulation, and underpin our observations with analyses of the phase space dynamics in the rate network. We find that the duration and stability of working memory representations are altered by astrocytic signaling and by noise. We show that astrocytic signaling modulates the mean duration of WM representations. Moreover, if the astrocytic regulation is strong, a slow presynaptic timescale introduces a 'window of vulnerability', during which WM representations are easily disruptable by noise before being stabilized. We identify two mechanisms through which noise from different sources in the network can either stabilize or destabilize WM representations. Our findings suggest that (i) astrocytic regulation can act as a crucial determinant for the duration of WM representations in synaptic attractor models of WM, and (ii) that astrocytic signaling could facilitate different mechanisms for volitional top-down control of WM representations and their duration.

Methods for determining the reduction potentials of flavin enzymes.

A key factor for flavoenzyme activity is the reduction potential of the bound flavin. The reduction potentials of protein-bound flavins span approximately a 500-mV range consistent with flavoenzymes having critical roles in metabolism and a variety of biological processes. Redox potentials of flavoenzymes have traditionally been determined using an electrode-based system with either direct or indirect electrochemical coupling between the protein and the working electrode. An electrode independent method, however, is also now commonly used and involves calculating the unknown flavin reduction potential of the protein from the known reduction potential of a reference or indicator dye. Here, the "classic" potentiometric method and the xanthine/xanthine oxidase methods are described. Both methods rely on equilibrium between protein-bound flavin and redox dyes. The potentiometric method measures the equilibrated redox potential of the protein-dye mixture whereas the xanthine/xanthine oxidase technique relies on slow continuous enzymatic reduction to maintain a constant equilibrium between the protein and the dyes. Because electrochemical equipment is not required, the xanthine/xanthine oxidase method is more accessible and convenient for researchers seeking to determine reduction potentials of flavoproteins or other biological redox centers such as hemes. The xanthine/xanthine oxidase method has been used to determine flavin reduction potentials from +132 to -417mV, demonstrating it is suitable for characterizing the redox properties of most flavoproteins.

Postoperative Opioid Use in Sinonasal Surgery.

OBJECTIVE: To survey patients following sinonasal surgery regarding postoperative pain and opioid use. STUDY DESIGN: Patients were surveyed for 4 days following sinus and/or nasal surgery regarding their pain level and use of prescribed opioids. SETTING: Four academic medical centers and 1 private practice institution. SUBJECTS: Consecutive adult patients undergoing sinonasal surgery. RESULTS: A total of 219 subjects met criteria and were included for analysis; 134 patients (61%) took 5 or fewer combination oxycodone (5-mg) and acetaminophen (325-mg) tablets in the first 3 postoperative days, and 196 patients (89.5%) took fewer than 15. Fifty-one patients (23%) consumed no opioid pain medication. Opioid consumption was positively correlated with postoperative pain ( R2 = 0.2, P < .01) but was not correlated with the use of acetaminophen ( R2 = 0.002, P = .48). No significant difference in postoperative pain or opioid consumption was seen with respect to age, sex, specific procedures performed, postoperative steroids, or smoking history. Current smokers reported higher average pain than nonsmokers ( P < .001) and also required more postoperative opioids ( P = .02). CONCLUSIONS: An evidence-based approach to postoperative pain control following sinonasal surgery that reduces the number of unused and potentially diverted opioids is needed. The current study suggests that 15 combination oxycodone (5-mg) and acetaminophen (325-mg) tablets provide sufficient pain control for 90% of patients in the immediate postoperative period following sinonasal surgery, irrespective of the specific procedures performed, use of acetaminophen, or use of systemic steroids. Smoking status may help surgeons predict which patients will require larger opioid prescriptions.

Review and update on postoperative opioid use after nasal and sinus surgery.

PURPOSE OF REVIEW: We examine the current literature on pain management after sinus and nasal surgery. The goal after surgery is to provide effective pain management without having too many 'leftovers', as leftover medications are an important source of opioids that are fueling the current prescription narcotic epidemic in the United States. There are more than 250 000 sinus operations and 260 000 septoplasties performed annually, and surgeons commonly prescribe a narcotic pain medication for postoperative pain management. RECENT FINDINGS: The literature suggests that an evidence-based approach may lead surgeons to prescribe significantly less narcotic pain medication for these procedures without affecting pain management. SUMMARY: An evidence-based approach to pain management can result in unchanged pain control and a significant positive impact on the narcotic abuse epidemic.