Cellular Contraction and Polarization Drive Collective Cellular Motion

Notbohm, J.,Banerjee, S.,Utuje, Kazage J.C.,Gweon, B.,Jang, H.,Park, Y.,Shin, J.,Butler, James P.,Fredberg, Jeffrey J.,Marchetti, M. Biophysical Society ; Published for the Biophysica 2016 Biophysical journal Vol.110 No.12

<P>Coordinated motions of close-packed multicellular systems typically generate cooperative packs, swirls, and clusters. These cooperative motions are driven by active cellular forces, but the physical nature of these forces and how they generate collective cellular motion remain poorly understood. Here, we study forces and motions in a confined epithelial monolayer and make two experimental observations: 1) the direction of local cellular motion deviates systematically from the direction of the local traction exerted by each cell upon its substrate; and 2) oscillating waves of cellular motion arise spontaneously. Based on these observations, we propose a theory that connects forces and motions using two internal state variables, one of which generates an effective cellular polarization, and the other, through contractile forces, an effective cellular inertia. In agreement with theoretical predictions, drugs that inhibit contractility reduce both the cellular effective elastic modulus and the frequency of oscillations. Together, theory and experiment provide evidence suggesting that collective cellular motion is driven by at least two internal variables that serve to sustain waves and to polarize local cellular traction in a direction that deviates systematically from local cellular velocity.</P>

Final report on APMP.RI(I)-K1: APMP/TCRI key comparison report of measurement of air kerma for ⁶⁰Co gamma-rays

Chun, K J,Butler, D J,Webb, D,Mahant, A K,Meghzifene, A,Lee, J H,Hah, S H,Kadni, T B,Zhang, Y,Kurosawa, T,Msimang, Z L M,Caseria, E S Springer-Verlag 2013 METROLOGIA -BERLIN- Vol.50 No.-

<P>The APMP.RI(I)-K1 key comparison of the measurement standards of air kerma for <SUP>60</SUP>Co gamma-rays was undertaken by the APMP/TCRI Dosimetry Working Group between 2004 and 2006, coordinated by the Korean Research Institute of Standards and Science (KRISS). In total, 10 institutes took part in the comparison, among which 7 were APMP member laboratories. Three Farmer-type commercial cavity chambers were used as transfer chambers and circulated among the participants. All the participants carried out their measurements according to the guidelines for the comparison established by the KRISS with the cooperation of the ARPANSA. For each transfer chamber, an NMI calibration coefficient was obtained and a ratio derived by dividing by the average result from the linking laboratories, ARPANSA and NMIJ. The APMP comparison reference value for each chamber was calculated as the mean of the NMI-determined calibration coefficients divided by the average result from the linking laboratories. The results showed that the maximum difference between the APMP linked ratio of a participating NMI and the APMP reference value was 1.76%.</P><P>The measured ratios of the calibration coefficient R<SUB>NMI, BIPM</SUB> between the participating NMI and the BIPM via the link laboratories for the transfer chambers were obtained. The maximum expanded uncertainty of R<SUB>NMI, BIPM</SUB> for any participating laboratory was 2.0%.</P><P>The degree of equivalence of each participating laboratory with respect to the key comparison reference value was also evaluated. The expanded uncertainty of the difference between the results ranged from 0.5% to 1.2%. The pair-wise degree of equivalence between each pair of laboratories was also obtained and the largest difference of the expanded uncertainty of the difference for any pair-wise degree of equivalence was within the expanded uncertainty of the measurement for the pair of laboratories.</P><P>Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.</P><P>The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>

A MACHINE-LEARNING METHOD TO INFER FUNDAMENTAL STELLAR PARAMETERS FROM PHOTOMETRIC LIGHT CURVES

Miller, A. A.,Bloom, J. S.,Richards, J. W.,Lee, Y. S.,Starr, D. L.,Butler, N. R.,Tokarz, S.,Smith, N.,Eisner, J. A. IOP Publishing 2015 The Astrophysical journal Vol.798 No.2

<P>A fundamental challenge for wide-field imaging surveys is obtaining follow-up spectroscopic observations: there are >10(9) photometrically cataloged sources, yet modern spectroscopic surveys are limited to similar to fewx10(6) targets. As we approach the Large Synoptic Survey Telescope era, new algorithmic solutions are required to cope with the data deluge. Here we report the development of a machine-learning framework capable of inferring fundamental stellar parameters (T-eff, log g, and [Fe/H]) using photometric-brightness variations and color alone. A training set is constructed from a systematic spectroscopic survey of variables with Hectospec/ Multi-Mirror Telescope. In sum, the training set includes similar to 9000 spectra, for which stellar parameters are measured using the SEGUE Stellar Parameters Pipeline (SSPP). We employed the random forest algorithm to perform a non-parametric regression that predicts Teff, log g, and [Fe/H] from photometric time-domain observations. Our final optimized model produces a cross-validated rms error (RMSE) of 165 K, 0.39 dex, and 0.33 dex for T-eff, log g, and [Fe/H], respectively. Examining the subset of sources for which the SSPP measurements are most reliable, the RMSE reduces to 125 K, 0.37 dex, and 0.27 dex, respectively, comparable to what is achievable via low-resolution spectroscopy. For variable stars this represents a approximate to 12%-20% improvement in RMSE relative to models trained with single-epoch photometric colors. As an application of our method, we estimate stellar parameters for similar to 54,000 known variables. We argue that this method may convert photometric time-domain surveys into pseudo-spectrographic engines, enabling the construction of extremely detailed maps of the Milky Way, its structure, and history.</P>

The EFFECTS of STATE and LOCAL TAX-BASED INCENTIVES on U.S. LABOR MARKETS, 1990–2015: BOON or BOONDOGGLE?

이학연,J.S. Butler 서울대학교행정대학원 2022 The Korean Journal of Policy Studies Vol.37 No.4

Clear evidence about the effectiveness of economic development incentives is limited. To bridge this research gap, this study uses the Upjohn Institute Panel Database on Incentives and Taxes (PDIT). Unemployment and employment rates are used to analyze the effectiveness of tax-based incentives. Statistical results indicate that tax incentives have a marginal impact on employment status and limited benefits to states. Only the R&D tax credit statistically significantly increases employment rates. This result supports the interpretation of economic development policies as a zero-sum game.

Neural correlates of oddball detection in self-motion heading: a high-density event-related potential study of vestibular integration.

Nolan, H,Butler, J S,Whelan, R,Foxe, J J,B?lthoff, H H,Reilly, R B Springer-Verlag 2012 Experimental brain research Vol.219 No.1

<P>The perception of self-motion is a product of the integration of information from both visual and non-visual cues, to which the vestibular system is a central contributor. It is well documented that vestibular dysfunction leads to impaired movement and balance, dizziness and falls, and yet our knowledge of the neuronal processing of vestibular signals remains relatively sparse. In this study, high-density electroencephalographic recordings were deployed to investigate the neural processes associated with vestibular detection of changes in heading. To this end, a self-motion oddball paradigm was designed. Participants were translated linearly 7.8 cm on a motion platform using a one second motion profile, at a 45 angle leftward or rightward of straight ahead. These headings were presented with a stimulus probability of 80-20 %. Participants responded when they detected the infrequent direction change via button-press. Event-related potentials (ERPs) were calculated in response to the standard (80 %) and target (20 %) movement directions. Statistical parametric mapping showed that ERPs to standard and target movements differed significantly from 490 to 950 ms post-stimulus. Topographic analysis showed that this difference had a typical P3 topography. Individual participant bootstrap analysis revealed that 93.3 % of participants exhibited a clear P3 component. These results indicate that a perceived change in vestibular heading can readily elicit a P3 response, wholly similar to that evoked by oddball stimuli presented in other sensory modalities. This vestibular-evoked P3 response may provide a readily and robustly detectable objective measure for the evaluation of vestibular integrity in various disease models.</P>

The X-ray counterpart to the gravitational-wave event GW170817

Troja, E.,Piro, L.,van Eerten, H.,Wollaeger, R. T.,Im, M.,Fox, O. D.,Butler, N. R.,Cenko, S. B.,Sakamoto, T.,Fryer, C. L.,Ricci, R.,Lien, A.,Ryan Jr, R. E.,Korobkin, O.,Lee, S.-K.,Burgess, J. M.,Lee, Nature Publishing Group 2017 Nature Vol. No.

A long-standing paradigm in astrophysics is that collisions—or mergers—of two neutron stars form highly relativistic and collimated outflows (jets) that power γ-ray bursts of short (less than two seconds) duration. The observational support for this model, however, is only indirect. A hitherto outstanding prediction is that gravitational-wave events from such mergers should be associated with γ-ray bursts, and that a majority of these bursts should be seen off-axis, that is, they should point away from Earth. Here we report the discovery observations of the X-ray counterpart associated with the gravitational-wave event GW170817. Although the electromagnetic counterpart at optical and infrared frequencies is dominated by the radioactive glow (known as a ‘kilonova’) from freshly synthesized rapid neutron capture (r-process) material in the merger ejecta, observations at X-ray and, later, radio frequencies are consistent with a short γ-ray burst viewed off-axis. Our detection of X-ray emission at a location coincident with the kilonova transient provides the missing observational link between short γ-ray bursts and gravitational waves from neutron-star mergers, and gives independent confirmation of the collimated nature of the γ-ray-burst emission.