Electrical measurements from large populations of animals would help reveal fundamental properties of the nervous system and neurological diseases. Small invertebrates are ideal for these large-scale studies; however, patch-clamp electrophysiology in microscopic animals typically requires low-throughput and invasive dissections. To overcome these limitations, we present nano-SPEARs: suspended electrodes integrated into a scalable microfluidic device. Using this technology, we have made the first extracellular recordings of body-wall muscle electrophysiology inside an intact roundworm, Caenorhabditis elegans. We can also use nano-SPEARs to record from multiple animals in parallel and even from other species, such as Hydra littoralis. Furthermore, we use nano-SPEARs to establish the first electrophysiological phenotypes for C. elegans models for Amyotrophic Lateral Sclerosis and Parkinson’s disease, and show a partial rescue of the Parkinson’s phenotype through drug treatment. These results demonstrate that nano-SPEARs provide the core technology for microchips that enable scalable, in vivo studies of neurobiology and neurological diseases.

Microfluidic devices allow scalable and customizable solutions for multi-modal interrogation of these soft, deformable Hydra.

An important feature of animal behavior is the ability to switch rapidly between activity states, however, how the brain regulates these spontaneous transitions based on the animal's perceived environment is not well understood. Here we show a C. elegans sleep-like state on a scalable platform that enables simultaneous control of multiple environmental factors including temperature, mechanical stress, and food availability. This brief quiescent state, which we refer to as microfluidic-induced sleep, occurs spontaneously in microfluidic chambers, which allows us to track animal movement and perform whole-brain imaging. With these capabilities, we establish that microfluidic-induced sleep meets the behavioral requirements of C. elegans sleep and depends on multiple factors, such as satiety and temperature. Additionally, we show that C. elegans sleep can be induced through mechanosensory pathways. Together, these results establish a model system for studying how animals process multiple sensory pathways to regulate behavioral states.

The cnidarian Hydra vulgaris provides an exciting opportunity to discover the relationship between animal behavior and the activity of every neuron in highly plastic, diffuse network of spiking cells. However, Hydra's deformable and contractile body makes it difficult to manipulate the local environment while recording neural activity. Here, we present a suite of microfluidic was not peer-reviewed) in the Public Domain. It is no longer restricted by copyright. Anyone can legally share, reuse, remix, or adapt thisThe copyright holder has placed this preprint (which . http://dx.doi.org/10.1101/257691 doi: bioRxiv preprint first posted online Jan. 31, 2018; 2 this technology may help reveal how highly plastic networks of neurons provide robust control of animal behavior.

A measurement of the absolute fluorescence yield of the 337 nm nitrogen band, relevant to ultra-high energy cosmic ray (UHECR) detectors, is reported. Two independent calibrations of the fluorescence emission induced by a 120 GeV proton beam were employed: Cherenkov light from the beam particle and calibrated light from a nitrogen laser. The fluorescence yield in air at a pressure of 1013 hPa and temperature of 293 K was found to be Y 337 = 5.61±0.06 stat ±0.21 syst photons/MeV. When compared to the fluorescence yield currently used by UHECR experiments, this measurement improves the uncertainty by a factor of three, and has a significant impact on the determination of the energy scale of the cosmic ray spectrum.Key words: Nitrogen Fluorescence Yield, Air Fluorescence Detection, Ultra-High Energy Cosmic Rays PACS: , 96.50. 96.50.sb, 96.50.sd, 32.50.+d, 34.50.Fa, 34.50.Gb IntroductionA well established technique for the detection of Ultra-High Energy ( 10 18 eV) Cosmic Rays (UHECRs) -first successfully employed by the Fly's Eye [1] and HiRes [2] experiments -is based on nitrogen fluorescence light emission induced by Extensive Air Showers (EAS). Excitation of atmospheric nitrogen by EAS charged particles results in fluorescence emission, mostly in the wavelength range between 300 and 430 nm. This UV light is measured as a function of time and incoming direction by photomultiplier cameras at the focus of large (few m 2 ) mirrors. Fluorescence telescopes measure the longitudinal EAS development in the atmosphere, which provides unique information on the primary cosmic ray's type and a calorimetric measurement of its energy.The fluorescence light yield along the EAS depends on the air pressure, temperature and humidity at the point of emission. In addition, wavelengthdependent atmospheric attenuation affects the light intensity reaching the telescope. Thus, the intensities of the fluorescence bands must be known for atmospheric conditions corresponding to the EAS development in the atmosphere, which ranges between about 2 km and 15 km above sea level. Early measurements of the fluorescence yield include those with low-energy stopped-particles in air by Bunner [3] and with electrons in air by Davidson and O'Neil [4]. A * corresponding author Email address: priviter@kicp.uchicago.edu (P. Privitera). The AIRFLY (AIR FLuorescence Yield) Collaboration has carried out an extensive program of measurements to significantly improve the precision on the fluorescence light yield. The fluorescence emission was studied as a function of the kinetic energy, ranging from keV to GeV, of particle beams at several accelerators [11]. The relative intensities of 34 fluorescence bands in the wavelength range from 284 to 429 nm, together with their pressure dependence, were reported in [12]. The temperature and humidity dependence of the main fluorescence bands was also measured [13]. These measurements have provided the most complete and consistent set of fluorescence yield data for UHECR calibration, establishing the relative ...

Zinc dialkyldithiophosphates (ZDDPs) are one of the most common anti-wear additives present in commercially-available motor oils. The ZDDP concentrations of motor oils are most commonly determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES). As part of an undergraduate research project, we have determined the Zn concentrations of eight commercially-available motor oils and one oil additive using neutron activation analysis (NAA), which has potential for greater accuracy and less sensitivity to matrix effects as compared to ICP-AES. The 31 P nuclear magnetic resonance ( 31 P-NMR) spectra were also obtained for several oil additive samples which have been heated to various temperatures in order to study the thermal decomposition of ZDDPs.

Experimental results are presented comparing the intensity of the bremsstrahlung produced by electrons with initial energies ranging from 10 to 20-keV incident on a thick Ag target, measured at forward angles in the range 0˚ to 55˚. When the data are corrected for attenuation due to photon absorption within the target, the results indicate that the detected radiation is distributed anisotropically only at photon energies, k, that are approximately equal to the initial energy of the incident electrons, E o . The results of our experiments suggest that as k /E o → 0, the detected radiation becomes essentially isotropic due primarily to the scattering of electrons within the target. A comparison to the theoretical work of Kissel et al. [6] suggests that the angular distribution of bremsstrahlung emitted by electrons incident on thick targets is similar to the angular distribution of bremsstrahlung emitted by electrons incident on free-atom targets only when k /E o ≈1. The experimental data are also in approximate agreement with the angular distribution predictions of the Monte Carlo program, PENELOPE.

Advances in microfabrication technologies and biomaterials have enabled a growing class of electronic devices that can stimulate and record bioelectronic signals. Many of these devices have been developed for humans or vertebrate animals, where miniaturization allows for implantation within the body. There are, however, another class of bioelectronic interfaces that exploit microfabrication and nanoelectronics to record signals from tiny, millimeter-sized organisms. In these cases, rather than implanting a device inside an animal, animals themselves are loaded in large numbers into bioelectronic devices for neural circuit and behavioral interrogation. These scalable interfaces provide platforms to develop new therapeutics as well as better understand basic principles of bioelectronic communication, neuroscience, and behavior. Here we review recent progress in these bioelectronic technologies and describe how they can complement on-chip optical, mechanical, and chemical interrogation methods to achieve high-throughput, multimodal studies of millimeter-sized small animals. ADVANTAGES OF MILLIMETER-SIZED ORGANISMS Small model organisms such as Caenorhabditis elegans, Drosophila, and zebrafish have been a cornerstone for understanding principles of neurobiology, behavior, genetics, and development (Davis, 2004; Sattelle and Buckingham, 2006; Stewart et al., 2014). Despite their small nervous systems and less anatomical complexity compared with that of mammalian models, there are significant advantages in using millimeter-sized animals to answer fundamental questions in neurobiology (Figure 1).