scholarly journals Neuropixels 2.0: A miniaturized high-density probe for stable, long-term brain recordings

Science ◽  
2021 ◽  
Vol 372 (6539) ◽  
pp. eabf4588
Author(s):  
Nicholas A. Steinmetz ◽  
Cagatay Aydin ◽  
Anna Lebedeva ◽  
Michael Okun ◽  
Marius Pachitariu ◽  
...  
Keyword(s):  
Time Scales ◽  
Small Animals ◽  
High Quality ◽  
Site Density ◽  
Long Time ◽  
Free Behavior ◽  
Post Hoc ◽  
Density Probe ◽  
Data Processing Methods

Measuring the dynamics of neural processing across time scales requires following the spiking of thousands of individual neurons over milliseconds and months. To address this need, we introduce the Neuropixels 2.0 probe together with newly designed analysis algorithms. The probe has more than 5000 sites and is miniaturized to facilitate chronic implants in small mammals and recording during unrestrained behavior. High-quality recordings over long time scales were reliably obtained in mice and rats in six laboratories. Improved site density and arrangement combined with newly created data processing methods enable automatic post hoc correction for brain movements, allowing recording from the same neurons for more than 2 months. These probes and algorithms enable stable recordings from thousands of sites during free behavior, even in small animals such as mice.

scholarly journals Neuropixels 2.0: A miniaturized high-density probe for stable, long-term brain recordings

2020 ◽  
Author(s):  
Nicholas A. Steinmetz ◽  
Cagatay Aydin ◽  
Anna Lebedeva ◽  
Michael Okun ◽  
Marius Pachitariu ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Small Animals ◽  
Site Density ◽  
Quality Signals ◽  
Free Behavior ◽  
Mouse Visual Cortex ◽  
Post Hoc ◽  
Density Probe ◽  
Data Processing Methods

AbstractTo study the dynamics of neural processing across timescales, we require the ability to follow the spiking of thousands of individually separable neurons over weeks and months, during unrestrained behavior. To address this need, we introduce the Neuropixels 2.0 probe together with novel analysis algorithms. The new probe has over 5,000 sites and is miniaturized such that two probes plus a headstage, recording 768 sites at once, weigh just over 1 g, suitable for implanting chronically in small mammals. Recordings with high quality signals persisting for at least two months were reliably obtained in two species and six different labs. Improved site density and arrangement combined with new data processing methods enable automatic post-hoc stabilization of data despite brain movements during behavior and across days, allowing recording from the same neurons in the mouse visual cortex for over 2 months. Additionally, an optional configuration allows for recording from multiple sites per available channel, with a penalty to signal-to-noise ratio. These probes and algorithms enable stable recordings from >10,000 sites during free behavior in small animals such as mice.

The Spread of Pollutants from Harbour Sludge Depots

1984 ◽  
Vol 16 (3-4) ◽  
pp. 623-633
Author(s):  
M Loxham ◽  
F Weststrate
Keyword(s):  
Time Scales ◽  
Molecular Diffusion ◽  
Near Field ◽  
Parameter Analysis ◽  
Migration Patterns ◽  
Long Time ◽  
Dilution Effects ◽  
Short Time ◽  
Harbour Sludge

It is generally agreed that both the landfill option, or the civil techniques option for the final disposal of contaminated harbour sludge involves the isolation of the sludge from the environment. For short time scales, engineered barriers such as a bentonite screen, plastic sheets, pumping strategies etc. can be used. However for long time scales the effectiveness of such measures cannot be counted upon. It is thus necessary to be able to predict the long term environmenttal spread of contaminants from a mature landfill. A model is presented that considers diffusion and adsorption in the landfill site and convection and adsorption in the underlaying aquifer. From a parameter analysis starting form practical values it is shown that the adsorption behaviour and the molecular diffusion coefficient of the sludge, are the key parameters involved in the near field. The dilution effects of the far field migration patterns are also illustrated.

Simulated Local and Remote Biophysical Effects of Afforestation over the Southeast United States in Boreal Summer*

2012 ◽  
Vol 25 (13) ◽  
pp. 4511-4522 ◽  
Author(s):  
Guang-Shan Chen ◽  
Michael Notaro ◽  
Zhengyu Liu ◽  
Yongqiang Liu
Keyword(s):  
United States ◽  
Carbon Sequestration ◽  
Time Scales ◽  
Boreal Summer ◽  
Surface Cooling ◽  
Local Cooling ◽  
Southeast United States ◽  
Long Time ◽  
Biophysical Effects

Abstract Afforestation has been proposed as a climate change mitigation strategy by sequestrating atmospheric carbon dioxide. With the goal of increasing carbon sequestration, a Congressional project has been planned to afforest about 18 million acres by 2020 in the Southeast United States (SEUS), the Great Lake states, and the Corn Belt states. However, biophysical feedbacks of afforestation have the potential to counter the beneficial climatic consequences of carbon sequestration. To assess the potential biophysical effects of afforestation over the SEUS, the authors designed a set of initial value ensemble experiments and long-term quasi-equilibrium experiments in a fully coupled Community Climate System Model, version 3.5 (CCSM3.5). Model results show that afforestation over the SEUS not only has a local cooling effect in boreal summer [June–August (JJA)] at short and long time scales but also induces remote warming over adjacent regions of the SEUS at long time scales. Precipitation, in response to afforestation, increases over the SEUS (local effect) and decreases over adjacent regions (remote effect) in JJA. The local surface cooling and increase in precipitation over SEUS in JJA are hydrologically driven by the changes in evapotranspiration and latent heat flux. The remote surface warming and decrease in precipitation over adjacent regions are adiabatically induced by anomalous subsidence. Our results suggest that the planned afforestation efforts should be developed carefully by taking account of short-term (local) and long-term (remote) biophysical effects of afforestation.

scholarly journals Long-Term Brightness Changes in Cool Pulsating Variables

1993 ◽  
Vol 139 ◽  
pp. 425-427
Author(s):  
John R. Percy
Keyword(s):  
Time Scales ◽  
Large Amplitude ◽  
Variable Star ◽  
American Association ◽  
Long Term Changes ◽  
Long Time ◽  
Red Giant

AbstractSeveral types of cool pulsating variables show unexplained long-term changes in brightness, typically on time scales of 10 to 20 times the basic (pulsational) period. The visual and photoelectric programs of the American Association of Variable Star Observers (AAVSO) are well-suited for detecting and studying these changes. Some examples are given here, including yellow hypergiants, RV Tauri stars, small- and large-amplitude red giant and super giant variables. The study of pulsating variables on long time scales provides “new perspectives” on their behavior.

scholarly journals X-ray variability in LINERs

2013 ◽  
Vol 9 (S304) ◽  
pp. 399-402
Author(s):  
Josefa Masegosa ◽  
Lorena Hernández-García ◽  
Isabel Márquez ◽  
Omaira González-Martín
Keyword(s):  
Active Galactic Nuclei ◽  
Time Scales ◽  
Galactic Nuclei ◽  
Spectral Variability ◽  
X Ray ◽  
Line Region ◽  
Variability Pattern ◽  
Long Time ◽  
Public Archives

AbstractOne of the most important features in active galactic nuclei (AGN) is the variability of their emission. Variability has been discovered at X-ray, UV, and radio frequencies on time scales from hours to years. Among the AGN family and according to theoretical studies, Low-Ionization Nuclear Emission Line Region (LINER) nuclei would be variable objects on long time scales. Our purpose is to investigate spectral X-ray variability in LINERs and to understand the nature of these kinds of objects, as well as their accretion mechanism. Chandra and XMM–Newton public archives were used to compile X-ray spectra of LINER nuclei at different epochs with time scales of years. To search for variability we fit all the spectra from the same object with a set of models, in order to identify the parameters responsible for the variability pattern. We found that long term spectral variability is very common, with variations mostly related to hard energies (2-10 keV). These variations are due to changes in the soft excess, and/or changes in the absorber, and/or intrinsic variations of the source.

scholarly journals Optical variability of quasars: a damped random walk

2013 ◽  
Vol 9 (S304) ◽  
pp. 395-398 ◽  
Author(s):  
Željko Ivezić ◽  
Chelsea MacLeod
Keyword(s):  
Random Walk ◽  
Time Scales ◽  
Model Parameters ◽  
Optical Wavelength ◽  
Long Time ◽  
Asymptotic Variability ◽  
Short Time ◽  
Quasar Variability ◽  
Best Fit

AbstractA damped random walk is a stochastic process, defined by an exponential covariance matrix that behaves as a random walk for short time scales and asymptotically achieves a finite variability amplitude at long time scales. Over the last few years, it has been demonstrated, mostly but not exclusively using SDSS data, that a damped random walk model provides a satisfactory statistical description of observed quasar variability in the optical wavelength range, for rest-frame timescales from 5 days to 2000 days. The best-fit characteristic timescale and asymptotic variability amplitude scale with the luminosity, black hole mass, and rest wavelength, and appear independent of redshift. In addition to providing insights into the physics of quasar variability, the best-fit model parameters can be used to efficiently separate quasars from stars in imaging surveys with adequate long-term multi-epoch data, such as expected from LSST.

scholarly journals Leadership for quality in long-term care

2021 ◽  
pp. 084047042110407
Author(s):  
Ivy L. Bourgeault ◽  
Tamara Daly ◽  
Catherine Aubrecht ◽  
Pat Armstrong ◽  
Hugh Armstrong ◽  
...  
Keyword(s):  
Long Term Care ◽  
Point Of Care ◽  
Methodological Approach ◽  
Care Staff ◽  
High Quality ◽  
Term Care ◽  
Leadership Standards ◽  
Non Profit ◽  
Post Hoc

Leadership in long-term care is a burgeoning field of research, particularly that which is focused on enabling point of care staff to provide high-quality and responsive healthcare. In this article, we focus on the relatively important role that leadership plays in enabling the conditions for high-quality long-term care. Our methodological approach involved a rapid in-depth ethnography undertaken by an interdisciplinary team across eight public and non-profit long-term care homes in Canada, where we conducted over 1,000 hours of observations and 275 formal and informal interviews with managers, staff, residents, family members and volunteers. Guiding our analysis post hoc is the LEADS in a Caring Environment framework. We mapped key promising leadership practices identified by our analysis and discuss how these can inform the development of leadership standards across staff and management in long-term care.

scholarly journals On the differences between two semi-empirical sea-level models for the last two millennia

2012 ◽  
Vol 8 (4) ◽  
pp. 3551-3581 ◽  
Author(s):  
M. Vermeer ◽  
S. Rahmstorf ◽  
A. Kemp ◽  
B. Horton
Keyword(s):  
North Carolina ◽  
Sea Level Rise ◽  
Sea Level ◽  
Time Scales ◽  
Long Time ◽  
Global Mean Sea Level ◽  
Semi Empirical ◽  
The Last Two Millennia ◽  
Global Mean

Abstract. We compare hindcasts of global mean sea level over the past millennium obtained using two semi-empirical models linking temperature and sea-level rise. The models differ in that one of them includes a term for a very long-term sea-level rise component unfolding over many millennia. On short (century) time scales, both models give very similar results. Proxy sea-level reconstructions from the northern (North Carolina) and southern (New Zealand and Tasmania) hemispheres are used to test the ability of both models to reproduce the longer-term sea-level evolution. In both comparisons the model including the second term produces a markedly better fit from 1000 AD to the present. When both models are used for generating sea-level projections, they behave similarly out to 2100 AD. Further out, to 2300–2500 AD, the projections differ significantly, in no small part due to different values for the sea-level response time scale τ obtained. We conclude that careful model validation on long time scales is important before attempting multi-century projections.

scholarly journals Temporal dynamics of functional networks in long-term infant scalp EEG

2020 ◽  
Author(s):  
Rachel J. Smith ◽  
Ehsan Alipourjeddi ◽  
Cristal Garner ◽  
Amy L. Maser ◽  
Daniel W. Shrey ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Time Scales ◽  
Temporal Dynamics ◽  
Time Of Day ◽  
Term Infant ◽  
Clustering Coefficient ◽  
Functional Networks ◽  
Principle Components Analysis ◽  
Long Time

AbstractHuman functional connectivity networks are modulated on time scales ranging from milliseconds to days. Rapid changes in connectivity over short time scales are a feature of healthy cognitive function, and variability over long time scales can impact the likelihood of seizure occurrence. However, relatively little is known about modulation of healthy functional networks over long time scales. To address this, we analyzed functional connectivity networks calculated from long-term EEG recordings from 19 healthy infants. Networks were subject-specific, as inter-subject correlations between weighted adjacency matrices were low. However, within individual subjects, both sleep and wake networks were stable over time, with stronger functional connectivity during sleep than wakefulness. This enabled automatic separation of wakefulness and sleep states via principle components analysis of the functional network time series, with median classification accuracy of 91%. Lastly, we found that network strength, degree, clustering coefficient, and path length significantly varied with time of day, when measured in both wakefulness and sleep. Together, these results suggest that modulation of healthy functional networks occurs over long timescales and is robust and repeatable. Accounting for such temporal periodicities may improve the physiological interpretation and use of functional connectivity analysis to investigate brain function in health and disease.

scholarly journals Keeping salamanders off the streets: Evaluating one of the first US amphibian road tunnels 30 years later

2019 ◽  
Author(s):  
Brandon P. Hedrick ◽  
Abby Vander Linden ◽  
Samantha A. Cordero ◽  
Edward Watt ◽  
Patrick M. O’Roark ◽  
...  
Keyword(s):  
United States ◽  
Time Scales ◽  
The United States ◽  
Ambystoma Maculatum ◽  
Anecdotal Evidence ◽  
Road Tunnels ◽  
Long Time ◽  
One Year ◽  
Term Data

AbstractCulverts are often installed under busy roads to help a variety of animals, from small frogs to bears, safely cross roads that bisect their habitats. One of the first roadway culvert systems designed specifically for amphibian use in the United States was installed along Henry Street in Amherst, Massachusetts in 1987 to protect spotted salamanders (Ambystoma maculatum). These salamanders cross Henry Street during their annual migration to their breeding pools. In recent years, anecdotal evidence from volunteers monitoring the site suggested that salamanders were no longer using the tunnels. To evaluate this concern we conducted salamander counts in 2016, 2017, and 2018 to quantify tunnel use. In 2016, only 11% of observed salamanders used the tunnels– a substantial decrease from 68% in 1988, one year after their installation, when the tunnels were last evaluated. Subsequently, we implemented two tunnel modifications in an effort to increase tunnel usage above the established 2016 baseline. Unfortunately, neither retrofit was successful. Previous studies have demonstrated that salamanders prefer minimum tunnel apertures of >0.4 m, so it is likely that the 0.2 m apertures here are inadequate. This may create differential light and humidity inside and outside the tunnels that is recognized by the salamanders. While many studies have evaluated amphibian tunnel use in lab and field settings, ours is one of the first studies to have examined tunnel usage data long after initial installation. These long-term data are critical for evaluating what factors are necessary for maintaining tunnels over decades-long time scales.

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