Long-term Record Research Articles

Evaluating heart rate variability with 10 second multichannel electrocardiograms in a large population-based sample.

Heart rate variability (HRV), defined as the variability of consecutive heart beats, is an important biomarker for dysregulations of the autonomic nervous system (ANS) and is associated with the development, course, and outcome of a variety of mental and physical health problems. While guidelines recommend using 5 min electrocardiograms (ECG), recent studies showed that 10 s might be sufficient for deriving vagal-mediated HRV. However, the validity and applicability of this approach for risk prediction in epidemiological studies is currently unclear to be used. This study evaluates vagal-mediated HRV with ultra-short HRV (usHRV) based on 10 s multichannel ECG recordings of N = 4,245 and N = 2,392 participants of the Study of Health in Pomerania (SHIP) from two waves of the SHIP-TREND cohort, additionally divided into a healthy and health-impaired subgroup. Association of usHRV with HRV derived from long-term ECG recordings (polysomnography: 5 min before falling asleep [N = 1,041]; orthostatic testing: 5 min of rest before probing an orthostatic reaction [N = 1,676]) and their validity with respect to demographic variables and depressive symptoms were investigated. High correlations (r = .52-.75) were revealed between usHRV and HRV. While controlling for covariates, usHRV was the strongest predictor for HRV. Furthermore, the associations of usHRV and HRV with age, sex, obesity, and depressive symptoms were similar. This study provides evidence that usHRV derived from 10 s ECG might function as a proxy of vagal-mediated HRV with similar characteristics. This allows the investigation of ANS dysregulation with ECGs that are routinely performed in epidemiological studies to identify protective and risk factors for various mental and physical health problems.

Differences in Long-Term Heart Rate Variability between Subjects with and without Metabolic Syndrome: A Systematic Review and Meta-Analysis.

Our aim was to determine the impact that metabolic syndrome (MS) produces in long-term heart rate variability (HRV), quantitatively synthesizing the results of published studies to characterize the cardiac autonomic dysfunction in MS. We searched electronic databases for original research works with long-term HRV recordings (24 h) that compared people with MS (MS+) versus healthy people as a control group (MS-). This systematic review and meta-analysis (MA) was performed according to PRISMA guidelines and registered at PROSPERO (CRD42022358975). A total of 13 articles were included in the qualitative synthesis, and 7 of them met the required criteria to be included in the MA. SDNN (-0.33 [-0.57, 0.09], p = 0.008), LF (-0.32 [-0.41, -0.23], p < 0.00001), VLF (-0.21 [-0.31, -0.10], p = 0.0001) and TP (-0.20 [-0.33, -0.07], p = 0.002) decreased in patients with MS. The rMSSD (p = 0.41), HF (p = 0.06) and LF/HF ratio (p = 0.64) were not modified. In long-term recordings (24 h), SDNN, LF, VLF and TP were consistently decreased in patients with MS. Other parameters that could be included in the quantitative analysis were not modified in MS+ patients (rMSSD, HF, ratio LF/HF). Regarding non-linear analyses, the results are not conclusive due to the low number of datasets found, which prevented us from conducting an MA.

Postoperative Impedance-Based Estimation of Cochlear Implant Electrode Insertion Depth.

Reliable determination of cochlear implant electrode positions shows promise for clinical applications, including anatomy-based fitting of audio processors or monitoring of electrode migration during follow-up. Currently, electrode positioning is measured using radiography. The primary objective of this study is to extend and validate an impedance-based method for estimating electrode insertion depths, which could serve as a radiation-free and cost-effective alternative to radiography. The secondary objective is to evaluate the reliability of the estimation method in the postoperative follow-up over several months. The ground truth insertion depths were measured from postoperative computed tomography scans obtained from the records of 56 cases with an identical lateral wall electrode array. For each of these cases, impedance telemetry records were retrieved starting from the day of implantation up to a maximum observation period of 60 mo. Based on these recordings, the linear and angular electrode insertion depths were estimated using a phenomenological model. The estimates obtained were compared with the ground truth values to calculate the accuracy of the model. Analysis of the long-term recordings using a linear mixed-effects model showed that postoperative tissue resistances remained stable throughout the follow-up period, except for the two most basal electrodes, which increased significantly over time (electrode 11: ~10 Ω/year, electrode 12: ~30 Ω/year). Inferred phenomenological models from early and late impedance telemetry recordings were not different. The insertion depth of all electrodes was estimated with an absolute error of 0.9 mm ± 0.6 mm or 22° ± 18° angle (mean ± SD). Insertion depth estimations of the model were reliable over time when comparing two postoperative computed tomography scans of the same ear. Our results confirm that the impedance-based position estimation method can be applied to postoperative impedance telemetry recordings. Future work needs to address extracochlear electrode detection to increase the performance of the method.

Multi-decade changes in the condition index of adult Pacific oysters (Crassostrea gigas) in response to climate in a US west coast estuary

Pacific oysters (Crassostrea gigas) were introduced to the US west coast in the early 1900's, but only regularly spawned in several discrete estuarine locations like Willapa Bay where conditions allowed for adult oyster gametogenesis as well as larval survival, retention, and settlement. Oyster industry participants have long recognized that the condition of marketable oysters was related to proximity of their growing areas to the ocean. This prompted resource managers to routinely collect data and identify trends in oyster condition index (CI) in this estuary. An analysis of this almost seven- decade long CI record revealed consistent trends across four sampling locations in Willapa Bay where 50–70% of the variability in CI was explained by a single component. This component of variability in CI was related most strongly to variability in the upwelling index (UI) which was positively correlated with CI during the summer upwelling season. A relationship with the Pacific Decadal Oscillation (PDO), a broader basin-scale index of temperature was also significant, but weaker and PDO was negatively correlated with CI. Shifts or breaks in the long-term CI record occurred in 1977/78 and 1999/2000 with another shift related to the second component of variation in CI that occurred in 1988/1989. The change in 1977/78 has previously been shown to correspond with a shift in the basin scale PDO, but more recent shifts appear to be correlated with local fluctuations in both temperature and upwelling intensity. Further investigation into shifts in the seasonal timing of temperature and phytoplankton as variables that control the oyster gametogenic cycle seem warranted.

First Clinical Experiences with the New DICOM Neurophysiology Standard.

Exchange of EEG data among institutions is complicated due to vendor-specific proprietary EEG file formats. The DICOM standard, which has long been used for storage and exchange of imaging studies, was expanded to store neurophysiology data in 2020. To implement DICOM as an interoperable and vendor-independent storage format for EEG recordings in the Clinic Hietzing. A pilot implementation for automated conversion of EEG data from a proprietary to standardized DICOM format was developed. Additionally, EEG review based on a central DICOM archive in a DICOM EEG viewer (encevis by AIT) was implemented. More than 200 long-term video EEG recordings and over 3000 routine EEGs were archived to the central DICOM archive of the WIGEV. Using DICOM as a storage format for EEG data is feasible and leads to a substantial improvement of interoperability and facilitates data exchange between institutions.

Forecasting imminent atrial fibrillation in long-term ECG recordings

Ultrathin films of model protein bovine serum albumin (BSA) are deposited at room temperature on hydrophilic and hydrophobic silicon surfaces in absence and presence of divalent ions and their hydrophobic, structural and morphological properties are investigated and compared. The hydrophobic property of the BSA films is evaluated using the water contact angle (CA) study. After adsorption on hydrophilic silicon surface (CA ≈ 20°), the hydrophobicity of pure and Ca2+ ions interacted BSA film is found to increase as CA values are obtained as ≈ 60° and 66.6° respectively, whereas on adsorption to hydrophobic silicon surface (CA ≈ 82°), the hydrophobicity decreases as CA changes to ≈ 72° and 77° respectively. The increment in CA or hydrophobicity of BSA films on both surfaces could be due to higher adsorption of BSA molecules in presence of divalent ions and due to more exposure of their hydrophobic residues towards the outer surface. Atomic force microscopy (AFM) images show deposition of smooth BSA films on both surfaces maintaining the globular structure. The structural properties obtained from X-ray reflectivity (XRR) studies show that a monolayer of tilted BSA molecules (≈ 45 Å) with its innate globular morphology is deposited on hydrophilic surface in absence of any ions but in the presence of divalent Ca2+ ions, bilayer of BSA molecules (≈ 70 Å) with tilted side-on orientation is deposited. Although, similar tilted monolayer is found to deposit on hydrophobic surface in absence of ions but the tilting is more with respect to surface as thicker (≈ 55 Å) and denser BSA layer is deposited. In presence of Ca2+ ions, tilted bilayer of BSA molecules (≈ 90 Å) is deposited on hydrophobic surface. Thus, in absence as well as in presence of divalent ions, higher adsorption of BSA molecules is confirmed on hydrophobic surface compared to hydrophilic surface.

Long-Term Continuous Computer Registration and Analysis of Motor Activity of a Group of Zebrafish Danio rerio.

A new algorithm for long-term continuous computer recording and analysis of motor activity of a group of zebrafish in the home tank has been developed. The movements of a group of Danio rerio during the entire light period and for several days are recorded at a frequency of 1 frame/sec in the form of short (15 min) files. Then these files are analyzed by the unique DanioStudo software, which, using a threshold algorithm and appropriate masks, calculates for each frame the sum of pixels associated with fish (the sum of fish silhouettes), and for two consecutive frames, the sum of altered pixels (the sum of altered fish silhouettes). The following indexes are calculated: the rate of sum of silhouettes alteration as the ratio of the sum of altered silhouettes to the sum of silhouettes (1) and the time spent in the selected area of the home tank as the ratio of the sum of silhouettes in this area to the sum of silhouettes in the entire tank (2). The mean rate of silhouette alteration correlates to the length of the path travelled by the fish and, therefore, serves as a correct measure of the motor activity of a group of fish. Using these algorithms, completely new data were obtained: it was shown that the motor activity of fish remains constant throughout the entire light period, but depends on the size of the home tank. The proposed approach, together with the DanioStudio software, can be effective in studying the dynamics of changes in the behavior of fish under long-term exposure to short daylight, drugs and toxic substances.

Auditory steady-state responses in the auditory cortex of mice during estrus cycle

Auditory-steady state responses (ASSRs) disclose the brain’s potency to oscillate and have been suggested to serve as biomarkers in various psychiatric disorders. GABAergic neurotransmission, a critical component of brain oscillations, is strongly influenced by sex hormones. In line, the severity of symptoms in psychiatric disorders has been linked to changes in sex hormones during the menstrual cycle. However, how these sex hormones affect ASSRs remain largely unknown. This was addressed by performing chronic recordings of ASSRs in mice while monitoring its estrus cycle. Here, the stability of ASSRs during long-term recordings was validated and showed good reliability. 40 Hz ASSRs showed changes throughout the estrus cycle where it decreased in the metestrus phase compared to the diestrus phase. In contrast, other frequency ASSRs did not show significant changes throughout the estrus cycle. Taken together, our findings illustrate that the estrus cycle may influence the generation of ASSRs and that the phase of the estrus cycle should be taken into consideration when ASSRs are recorded in females.

Geo-archaeology and Haíɫzaqv oral history: Long-term human investment and resource use at EkTb-9, Triquet Island, N̓úláw̓itxˇv Tribal Area, Central Coast, British Columbia, Canada

Archaeological site EkTb-9 is located on Triquet Island in the N̓úláw̓itxˇv Tribal area of Haíɫzaqv (Heiltsuk) Nation territory, on the Central Coast of British Columbia, Canada. The results of radiometric dating and the analysis of palaeoenvironmental correlates indicate that the site was a persistent place of repeated human occupation spanning the early post-glacial period to the present day. This paper focuses on the paleogeographic and geomorphic setting of EkTb-9. Stratigraphic records show a complex array of site formation processes. Marine beach sediments are elevated above modern sea level, an extensive sand sheet consistent with a possible palaeotsunami event is present, as well as organic soils and peat deposits. Cultural strata are interbedded with these and include both shell-less and preserved shell accumulations. Results from our geo-archaeological and palaeoenvironmental assessments indicate that the outer coastal island changed from what was likely an open landscape during the early post-glacial period to the hypermaritime coastal temperate rainforest environs of the present day. Our interpretations are combined with Haíɫzaqv oral history and discussions are organized by Haíɫzaqv temporal phases identified for the N̓úláw̓itxˇv Tribal area. Combining Indigenous knowledge with our archaeological interpretations enhances our collective understanding of the long-term record of human occupation and investment at EkTb-9.

Semaphorin 4D induced inhibitory synaptogenesis decreases epileptiform activity and alters progression to Status Epilepticus in mice

Previously we demonstrated that intra-hippocampal infusion of purified, Semaphorin 4D (Sema4D) extracellular domain (ECD) into the mouse hippocampus rapidly promotes formation of GABAergic synapses and decreases seizure susceptibility in mice. Given the relatively fast action of Sema4D treatment revealed by these studies, we sought to determine the time course of Sema4D treatment on hippocampal network activity using an acute hippocampal slice preparation. We performed long-term extracellular recordings from area CA1 encompassing a 2-hour application of Sema4D and found that hippocampal excitation is suppressed for hours following treatment. We also asked if Sema4D treatment could ameliorate seizures in an acute seizure model: the kainic acid (KA) mouse model. We demonstrate that Sema4D treatment delays and suppresses ictal activity, delays the transition to Status Epilepticus (SE), and lessens the severity of SE. Lastly, we sought to explore alternative methods of Sema4D delivery to hippocampus and thus created an Adeno Associated Virus expressing the ECD of Sema4D. Our data reveal that virally delivered, chronically overexpressed Sema4D-ECD promotes GABAergic synapse formation and suppresses ictal activity and progression to SE. These results provide proof of concept that viral delivery of Sema4D is an efficacious and promising delivery method to abate epileptiform activity and progression to SE.

Investigation of the Mid-Age (65–34 ka) Period of Taranaki Volcano, New Zealand: Indications for the Effect of Volcano Growth

ABSTRACT Many stratovolcanoes are characterised by cycles of edifice growth interrupted by collapse events. The long-term record of the evolution of such magmatic systems is mainly preserved in the deposits of the volcanic apron surrounding the active cone. Taranaki Volcano in New Zealand provides an unusually detailed example of these processes due to excellent coastal ring-plain and young cone exposures. In this study, we investigate the magmatic system of this volcano through three consecutive growth phases by sampling a detailed, stratigraphically controlled selection of volcanic clasts from volcaniclastic mass-flow deposits in the medial ring-plain. The clasts from three growth phases (GP1, 65–55 ka; GP2, 55–40 ka; GP3, 40–34 ka) differ in bulk composition and form geochemically distinct trends on variation diagrams. These trends can be modelled by mainly dacitic melt mixing with gabbroic and ultramafic xenolith compositions representing the plutonic assemblages beneath the edifice. Within short-term growth cycles (104 years), the geochemical differences between lower and upper sequences of GP units indicate that closer to an edifice collapse, both whole-rock major and trace element compositions display more evolved and scattered trends compared to post-collapse stages. Considering the long-term magmatic evolution of Taranaki Volcano, it is apparent that the pre-collapse compositions are more evolved than bulk rock compositions of the growth phases, indicating active upper-crustal reservoir conditions in pre-collapse states. Furthermore, the volume losses caused by sector collapses prior to GP2 and GP3 could decrease the pressure in the upper-crustal reservoir. Overall, the data obtained from the mid-age Taranaki volcanic system elucidate the mid- to upper-crustal magmatic processes and reservoir conditions throughout growth cycles. Further, it demonstrates the top-down control of volcanic edifice load change on the magmatic plumbing system expressed by the evolvement of whole-rock compositions towards the end of a growth cycle.

Local field potentials in major depressive and obsessive-compulsive disorder: a frequency-based review.

The purpose of this paper is to provide a mini-review covering the recent progress in human and animal studies on local field potentials (LFPs) of major depressive disorder (MDD) and obsessive-compulsive disorder (OCD). PubMed and EMBASE were searched to identify related studies. Inclusion criteria were (1) reported the LFPs on OCD or MDD, (2) published in English, and (3) human or animal studies. Exclusion criteria were (1) review or meta-analysis or other literature types without original data and (2) conference abstract without full text. Descriptive synthesis of data was performed. Eight studies on LFPs of OCD containing 22 patients and 32 rats were included: seven were observational studies with no controls, and one animal study included a randomized and controlled phase. Ten studies on LFPs of MDD containing 71 patients and 52 rats were included: seven were observational studies with no controls, one study with control, and two animal studies included a randomized and controlled phase. The available studies revealed that different frequency bands were associated with specific symptoms. Low frequency activity seemed to be closely related to OCD symptoms, whereas LFPs findings in patients with MDD were more complicated. However, limitations of recent studies restrict the drawing of definite conclusions. Combined with other measures such as Electroencephalogram, Electrocorticography, or Magnetoencephalography and long-term recordings in various physiological states (rest state, sleep state, task state) could help to improve the understanding of potential mechanisms.

The influence of stimulus history on directional coding in the monarch butterfly brain.

The central complex is a brain region in the insect brain that houses a neural network specialized to encode directional information. Directional coding has traditionally been investigated with compass cues that revolve in full rotations and at constant angular velocities around the insect's head. However, these stimulus conditions do not fully simulate an insect's sensory perception of compass cues during navigation. In nature, an insect flight is characterized by abrupt changes in moving direction as well as constant changes in velocity. The influence of such varying cue dynamics on compass coding remains unclear. We performed long-term tetrode recordings from the brain of monarch butterflies to study how central complex neurons respond to different stimulus velocities and directions. As these butterflies derive directional information from the sun during migration, we measured the neural response to a virtual sun. The virtual sun was either presented as a spot that appeared at random angular positions or was rotated around the butterfly at different angular velocities and directions. By specifically manipulating the stimulus velocity and trajectory, we dissociated the influence of angular velocity and direction on compass coding. While the angular velocity substantially affected the tuning directedness, the stimulus trajectory influenced the shape of the angular tuning curve. Taken together, our results suggest that the central complex flexibly adjusts its directional coding to the current stimulus dynamics ensuring a precise compass even under highly demanding conditions such as during rapid flight maneuvers.

Temporally variable recurrence regimes of mega-tsunamis in the 6500 years prior to the 2004 Indian Ocean event

The analyses of cores retrieved from three sites near Port Blair (South Andaman) revealed out-of-sequence deposits at various depths. They are identified as previous episodes of tsunami by their sediment characteristics and microfossil content, using the 2004 event deposition as a template. These deposits have median ages of 601 cal. yr BP, 837 cal. yr BP, 1440 cal. yr BP, 3018 cal. yr BP, 3591 cal. yr BP, 4712 cal. yr BP, 5607 cal. yr BP, and 6357 cal. yr BP and are chronologically equivalent of those from the far-field locations in the Indian Ocean region. The distant deposits that are correlated with the South Andaman sites most likely owe their origin to the 2004-type events, as indicated by tsunami simulations in the study region. The long-term record presented here is characterized by an early phase of a quasiperiodic recurrence regime that transitions into a distinct interval of temporally clustered events. The quasiperiodic regime that appears around the mid-Holocene with an inter-event interval of 980 ± 385 years is followed by a sizable quiescent period of 1605 ± 245 years, before being succeeded by a regime of temporally clustered events. The chronology of nine tsunami events in the last 6500 years from the Indian Ocean region, thus implies a nonlinear pattern for the causative earthquakes. As demonstrated in the subduction zones elsewhere, the temporal variability of tsunamigenic great earthquakes is supported by the theoretical models espousing the characteristics of long-term stress recycling processes active within the subduction zones and transfer processes between the lower viscoelastic layer and the upper seismogenic crust.

Review and assessment of the donor safety among plasma donors.

Review and assessment of the donor safety among plasma donors.

Deciphering the Africa-Arabia breakup: Insights from U-Pb dating along the Carmel-Gilboa fault system and its triple junction with the Dead Sea transform

The Carmel–Gilboa fault system (CGFS) runs sub-parallel to the Azraq–Sirhan Garben (ASG) and the Red Sea Rift. Although the system currently forms a triple junction with the Dead Sea transform (DST), its initiation is considered to be associated with NE–SW extensional regime during the Africa-Arabia breakup in the late Oligocene to early Miocene. The role of the CGFS in the breakup process is not fully understood. In addition, the exact timing of initiation and potential reactivation during the onset of the DST plate boundary is not well constrained. This work sheds light on these events by establishing a long-term record of deformation along the CGFS and its intersection with the DST. This study presents 17 U-Pb ages of syn-tectonic calcite (n=14, ∼33.2 to 2.3 Ma) collected along the CGFS. These ages suggest that the earliest faulting phase along the CGFS took place between ∼25 to ∼21 Ma - coinciding with the initiation of the Red Sea Rift. The second phase of activity along the CGFS commenced at ∼16 Ma. This phase supports northward propagation of the DST from the Gulf of Elat to the southern tip of the Lebanese restraining bend from ∼18 to ∼14 Ma. The new U-Pb ages along the CGFS together with ages from the DST constrain the propagation rate of the DST to ∼105 mm/year, roughly 20 times faster than the current left-lateral offset along this active plate boundary (∼5 mm/year). The trigger for two simultaneous rifts, located 500 km apart and the distributed extension along the northern Red Sea is most probably related to the relative mechanical strength of oceanic vs. continental lithosphere, which also controls the eventual establishment of the DST and the failure of the rifting process along the CGFS-Azraq-Sirhan rift system.

The Salinity of the Great Salt Lake and Its Deep Brine Layer

The Great Salt Lake is a highly saline terminal lake with considerable fluctuations in water surface elevation and salinity. The lake is divided into two arms by a railroad causeway. River inflows enter the larger south arm, while the north arm only receives minimal surface runoff. Evaporation from both arms and limited exchange of water and salt through causeway openings result in complex water and salinity processes in the lake. The north arm is typically homogeneous and close to saturation. The south arm is typically stratified with periodic occurrences of a deep brine layer. This paper analyzes the lake’s long-term historical salinity and water surface elevation data record. Its purpose is to better document the movement of salt and changes to salinity in time and space within the lake and the occurrence and extent of its deep brine layer. This work is important because of the lake’s salinity-dependent ecosystem and industries as well as the role played by the deep brine layer in the concentration of salt and contaminants. We documented that the deep brine layer in the south arm is intermittent, occurring only when causeway exchange supports flow from the north to the south arms. We found that the overall mass of salt in the lake is declining and quantified this in terms of mineral extraction records and historical density measurements.

Water availability and seasonality shape elemental stoichiometry across space and time.

The interaction of climate change and increasing anthropogenic water withdrawals is anticipated to alter surface water availability and the transport of carbon (C), nitrogen (N), and phosphorus (P) in river networks. But how changes to river flow will alter the balance, or stoichiometry, of these fluxes is unknown. The Lower Flint River Basin (LFRB) is part of an interstate watershed relied upon by several million people for diverse ecosystem services, including seasonal crop irrigation, municipal drinking water access, and public recreation. Recently, increased water demand compounded with intensified droughts have caused historically perennial streams in the LFRB to cease flowing, increasing ecosystem vulnerability. Our objectives were to quantify how riverine dissolved C: N: P varies spatially and seasonally and determine how monthly stoichiometric fluxes varied with overall water availability in a major tributary of LFRB. We used a long-term record (21-29 years) of solute water chemistry (dissolved organic carbon, nitrate/nitrite, ammonia, and soluble reactive phosphorus) paired with long-term stream discharge data across six sites within a single LFRB watershed. We found spatial and seasonal differences in soluble nutrient concentrations and stoichiometry attributable to groundwater connections, the presence of a major floodplain wetland, and flow conditions. Further, we showed that water availability, as indicated by the Palmer Drought Severity Index (PDSI), strongly predicted stoichiometry with generally lower C:N and C:P and higher N:P fluxes during periods of low water availability (PDSI < -4). These patterns suggest there may be long term and significant changes to stream ecosystem function as water availability is being dramatically altered by human demand with consequential impacts to solute transport, in-stream processing, and stoichiometric ratios. This article is protected by copyright. All rights reserved.

154 Comparison of Chronic and Intraoperative LFP and ECoG Recordings in Humans With Parkinson’s Disease

INTRODUCTION: Advances in implantable neurotechnologies have enabled chronic invasive long-term recordings of field potentials from depth leads or paddle-type electrocorticography (ECoG) leads. The relationship between these long-term recordings and those obtained acutely in the operating room has not been studied. METHODS: Human subjects (n=6) with movement disorders (Parkinson’s disease, dystonia) were permanently implanted with quadripolar DBS leads, and quadripolar ECoG leads over primary motor and sensory cortices, attached to a Medtronic Summit RC+S investigational device in the chest. Recordings were acquired intraoperatively using a NeuroOmega (Alpha Omega, Inc) recording system customized for research use. RC+S recordings were acquired between 1 and 345 days post implantation. The same processing pipeline was applied to both data sets, and average power spectra in canonical frequency bands (delta, theta, alpha, beta, gamma) were compared using rank sum tests within each subject. RESULTS: Power spectra show similar power law scaling phenomena between intraoperative and chronic recordings. Disease specific frequency band characteristics such as beta peaks could be seen in both chronic and intraoperative recordings, however, within subjects these were not always consistently seen. CONCLUSIONS: We present within-patient comparisons of signal characteristics (power spectra) of intraoperative recordings from a research grade recording system, with wirelessly streamed data from a chronic implantable device, using the same brain leads. Power spectra have similar characteristics between the intraoperative and long term recordings, however, there are distinct differences between the intraoperative and longer term clinic recordings, reinforcing the utility of tracking neural signals over time after the effects of lead insertion on the motor circuit have diminished.

The Isotopic Composition of Rainfall on a Subtropical Mountainous Island

Abstract Tropical islands are simultaneously some of the most biodiverse and vulnerable places on Earth. Water resources help maintain the delicate balance on which the ecosystems and the population of tropical islands rely. Hydrogen and oxygen isotope analyses are a powerful tool in the study of the water cycle on tropical islands, although the scarcity of long-term and high-frequency data makes interpretation challenging. Here, a new dataset is presented based on weekly collection of rainfall H and O isotopic composition on the island of O‘ahu, Hawai‘i, beginning from July 2019 and still ongoing. The data show considerable differences in isotopic ratios produced by different weather systems, with Kona lows and upper-level lows having the lowest δ2H and δ18O values, and trade-wind showers the highest. The data also show significant spatial variability, with some sites being characterized by higher isotope ratios than others. The amount effect is not observed consistently at all sites. Deuterium excess shows a marked seasonal cycle, which is attributed to the different origin and history of the air masses that are responsible for rainfall in the winter and summer months. The local meteoric water line and a comparison of this dataset with a long-term historical record illustrate strong interannual variability and the need to establish a long-term precipitation isotope monitoring network for Hawai‘i. Significance Statement The isotopic composition of water is often used in the study of island water resources, but the scarcity of high-frequency datasets makes the interpretation of data difficult. The purpose of this study is to investigate the isotopic composition of rainfall on a mountainous island in the subtropics. Based on weekly data collection on O‘ahu, Hawai‘i, the results improve our understanding of the isotopic composition of rainfall due to different weather systems, like trade-wind showers or cold fronts, as well as its spatial and temporal variability. These results could inform the interpretation of data from other mountainous islands in similar climate zones.