Myelin Formation and Remodeling

Myelin is a multilayer wrapping of insulation formed by glial cells around axons that is essential for rapid impulse transmission, but how glial cells accomplish this cellular choreography has long intrigued researchers. In this issue of Cell, Snaidero et al., provide new insights into how myelin forms and is remodeled

Imaging Single Photons and Intrinsic Optical Signals for Studies of Vesicular and Non-Vesicular ATP Release from Axons

The temporal and spatial dynamics of neurotransmitter release are fundamental to understanding activity-dependent signaling between axons and other cells, including neurons, glia, and vascular cells. A microscopic imaging technique is described that enables studying release of the neurotransmitter ATP from axons in response to action potentials. The method combines imaging single-photons, intrinsic optical signal imaging, and high magnification time-lapse microcopy to enable investigations of action potential-induced ATP release together with cell morphology and activity-dependent axon swelling. ATP released from axons catalyzes a chemiluminescent reaction between luciferin and luciferase that generates single photons that can be imaged individually. In addition to vesicular release, ATP release through membrane channels activated by axon swelling was monitored simultaneously with intrinsic optical signals. Repeated emissions of photons were observed from localized 15 μm regions of axons, with a frequency distribution that differed from a normal distribution and from the frequency of emissions outside these localized regions

Faculty Senate Structure: A Proposal Including Budgets

It has become increasingly difficult for the Faculty Senate, the FS President and the Operations Committee (OPS) to adequately meet all the legitimate needs and time demands of their respective roles. It is also increasingly difficult for the Faculty Senate to respond to new initiatives and weigh in proactively on strategic directives coming from the Administration, the Regents, and our wider organizational environment. If shared governance within the University is to really work well, and lead UNM in the best strategic pursuit of its academic mission in the future, we believe we simply have to havea structure that both embodies democratic practice andis capable of responding in an efficient way which is less centralized in the person of the FS President

Large Woody Debris on the Carmel River From Camp Steffani To Carmel Lagoon Fall 2015

The following report documents the Fall 2015 locations and characteristics of large woody debris (LWD) along the lower reach of the Carmel River in California, from Camp Steffani Road to the Carmel Lagoon. The report includes an ArcMap GIS project and electronic spreadsheets containing the data

Regulation of Myelin Genes Implicated in Psychiatric Disorders by Functional Activity in Axons

Myelination is a highly dynamic process that continues well into adulthood in humans. Several recent gene expression studies have found abnormal expression of genes involved in myelination in the prefrontal cortex of brains from patients with schizophrenia and other psychiatric illnesses. Defects in myelination could contribute to the pathophysiology of psychiatric illness by impairing information processing as a consequence of altered impulse conduction velocity and synchrony between cortical regions carrying out higher level cognitive functions. Myelination can be altered by impulse activity in axons and by environmental experience. Psychiatric illness is treated by psychotherapy, behavioral modification, and drugs affecting neurotransmission, raising the possibility that myelinating glia may not only contribute to such disorders, but that activity-dependent effects on myelinating glia could provide one of the cellular mechanisms contributing to the therapeutic effects of these treatments. This review examines evidence showing that genes and gene networks important for myelination can be regulated by functional activity in axons

Suppression of Back-to-Back Hadron Pairs at Forward Rapidity in d+ Au Collisions at sqrt [s_ {NN}]= 200 GeV

Back-to-back hadron pair yields in d+Au and p+p collisions at √sNN=200  GeV were measured with the PHENIX detector at the Relativistic Heavy Ion Collider. Rapidity separated hadron pairs were detected with the trigger hadron at pseudorapidity |η|\u3c0.35 and the associated hadron at forward rapidity (deuteron direction, 3.0\u3cη\u3c3.8). Pairs were also detected with both hadrons measured at forward rapidity; in this case, the yield of back-to-back hadron pairs in d+Au collisions with small impact parameters is observed to be suppressed by a factor of 10 relative to p+p collisions. The kinematics of these pairs is expected to probe partons in the Au nucleus with a low fraction x of the nucleon momenta, where the gluon densities rise sharply. The observed suppression as a function of nuclear thickness, pT, and η points to cold nuclear matter effects arising at high parton densities

Transverse-Momentum Dependence of the J/psi Nuclear Modification in d+ Au Collisions at sqrt (s_NN)= 200 GeV

We present measured J/ψ production rates in d+Au collisions at √sNN = 200 GeV over a broad range of transverse momentum (pT = 0–14 GeV/c) and rapidity (−2.2 \u3c y \u3c 2.2). We construct the nuclear-modification factor RdAu for these kinematics and as a function of collision centrality (related to impact parameter for the RdAu collision). We find that the modification is largest for collisions with small impact parameters, and observe a suppression (RdAu \u3c 1) for pT \u3c 4 GeV/c at positive rapidities. At negative rapidity we observe a suppression for pT \u3c 2 GeV/c then an enhancement (RdAu \u3e 1) for pT \u3e 2 GeV/c. The observed enhancement at negative rapidity has implications for the observed modification in heavy-ion collisions at high pT

J/ψ suppression at forward rapidity in Au+ Au collisions at sqrt [s_ {NN}]= 200 GeV

Heavy quarkonia are observed to be suppressed in relativistic heavy-ion collisions relative to their production in p + p collisions scaled by the number of binary collisions. In order to determine if this suppression is related to color screening of these states in the produced medium, one needs to account for other nuclear modifications including those in cold nuclear matter. In this paper, we present new measurements from the PHENIX 2007 data set of J/ψ yields at forward rapidity (1.2 \u3c |y| \u3c 2.2) in Au + Au collisions at √sNN = 200 GeV. The data confirm the earlier finding that the suppression of J/ψ at forward rapidity is stronger than at midrapidity, while also extending the measurement to finer bins in collision centrality and higher transverse momentum (pT ). We compare the experimental data to the most recent theoretical calculations that incorporate a variety of physics mechanisms including gluon saturation, gluon shadowing, initial-state parton energy loss, cold nuclear matter breakup, color screening, and charm recombination.We find J/ψ suppression beyond cold-nuclear-matter effects. However, the current level of disagreement between models and d + Au data precludes using these models to quantify the hot-nuclear-matter suppression

Deviation from quark-number scaling of the anisotropy parameter v_2 of pions, kaons, and protons in Au+ Au collisions at sqrt (s_NN)= 200 GeV

Measurements of the anisotropy parameter v2 of identified hadrons (pions, kaons, and protons) as a function of centrality, transverse momentum pT , and transverse kinetic energy KET at midrapidity (|_| \u3c 0.35) in Au+Au collisions at psNN = 200 GeV are presented. Pions and protons are identified up to pT = 6 GeV/c, and kaons up to pT = 4 GeV/c, by combining information from time-of-flight and aerogel ˇ Cerenkov detectors in the PHENIX Experiment. The scaling of v2 with the number of valence quarks (nq) has been studied in different centrality bins as a function of transverse momentum and transverse kinetic energy. A deviation from previously observed quark-number scaling is observed at large values of KET /nq in noncentral Au+Au collisions (20–60%), but this scaling remains valid in central collisions (0–10%)

Cold Nuclear Matter Effects on J/ψ Yields as a Function of Rapidity and Nuclear Geometry in d+ A Collisions at sqrt [s_ {NN}]= 200 GeV

We present measurements of J/ψ yields in d+Au collisions at √sNN=200  GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/ψ rapidity (-2.