A New Tribe of Saber-toothed Cats (\u3ci\u3eBarbourofelini\u3c/i\u3e) from the Pliocene of North America

A new genus of Pliocene Saber-toothed felid, Barbourofelis, is proposed and two new species B. fricki and B. morrisi are described. These two forms and other described material represent an unusual lineage of felids with long sabers, shortened crania, and massive postorbital bars. The tribal name Barbourofelini is proposed for this lineage which is presently known in North America from deposits ranging in age from Clarendonian through Kimballian. The Barbourofelini apparently migrated from Eurasia to North America in the Late Miocene or Early Pliocene. Sansanosmilus of the French Vindobonian appears to represent the ancestral stock of these cats. The following genera of other saber-toothed felids are discussed: Hoplophoneus, Eusmilus, Dinictis, Nimravus, Ekgmoiteptecela, Ma.chairodus, Ischyrosmilus, Homotherium, H. (Dinobastis), Megantereon, and Smilodon. The two generic names Albanosmilus and Grivasmilus also are considered. The continued usage of the provincial age terms Valentinian and Kimballian is recommended, and a faunal list for these units in Nebraska is provided

Bears (Ursidae) from the Late Cenozoic of Nebraska

A ramus and partial premaxilla establish the presence of a new subspecies of Indarctos in the upper Pliocene (Kimball Formation, Ogallala Group) of Frontier County, Nebraska. An extremely large species of Agriotherium is represented by fragmentary remains from the middle Pliocene (middle part of Ash Hollow Formation, Ogallala Group) of Sherman County, Nebraska. This study is part of a series of papers dealing primarily with the fauna of the Kimball formation in Nebraska (Barbour 1927, 1929; Barbour and Schultz, 1941; Schultz and Stout, 1948, 1961; Kent 1963, 1967; Tanner, 1967; Short, 1969; Martin and Tate, 1970; Schultz, Schultz, and Martin, 1970). The Kimballian fauna from Nebraska differs from the Hemphillian fauna in that most of the known forms are markedly more advanced, but definitely pre-Blancan (Early Pleistocene). A large bear, Indarctos oregonensis keithi, new subspecies, from U.N.S.M. Coli. Loc. Ft-40 is included in the Kimballian fauna from Nebraska. An edentulous ramus and a radius of Agriotherium brought in by Frank Garvel of Ashton, Nebraska, from near U.N.S.M. Coll. Loc. Sm-101 in Sherman County, Nebraska, is also reported. This latter locality is Hemphillian in age (Ash Hollow Formation) and has produced Machairodus as well as some rhinoceros material (personal communication from Lloyd Tanner)

Two Lynx-like Cats from the Pliocene and Pleistocene

A new species (Lynx stouti) of small felid is described from the lower Pliocene of Colorado. This form has several characters in common with the modern Lynx and may be ancestral to that genus. A new subspecies of Lynx issiodorensis Croizet and Jobert is described as L. i. kurteni from the Mullen Assemblage, Cherry County, Nebraska. The relationships of this form to other lynxes are discussed along with the paleo-distribution of the genus. The classification of the felinae has always been somewhat controversial, especially at the generic level. One fairly homogenous group of cats which has been separated from the genus Fe/is are the lynxes. The ancestors of the modern lynxes can be traced back at least to the Villafranchian although the early forms did not have the characteristic short body and long legs found in the living species (Kurten, 1968, p. 80). New material from the Early Pliocene of Colorado U.N.S.M.4 25490 suggests that the separation of these small felids from other lines of felid evolution may have occurred quite early. By the Early Pleistocene the lynxes had already achieved a holartic distribution and are found in the Villafranchian of Europe and China as well as in the Blancan of North America. The characteristic form of this period is Lynx issiodorensis Croizet and Jobert which is known primarily from the Villafranchian of Europe. This species, or very closely related forms, are also known from Early Pleistocene sediments in North America and add strength to the already considerable arguments (Schultz and Stout, 1945, 1948; Schultz and Martin, 1970) for the correlation of the Villafranchian with the Blancan

Reaction-Diffusion Processes as Physical Realizations of Hecke Algebras

We show that the master equation governing the dynamics of simple diffusion and certain chemical reaction processes in one dimension give time evolution operators (Hamiltonians) which are realizations of Hecke algebras. In the case of simple diffusion one obtains, after similarity transformations, reducible hermitian representations while in the other cases they are non-hermitian and correspond to supersymmetric quotients of Hecke algebras.Comment: Latex, 6 pages, BONN-HE-93.1

Adaptive Prediction Error Coding in the Human Midbrain and Striatum Facilitates Behavioral Adaptation and Learning Efficiency.

Effective error-driven learning benefits from scaling of prediction errors to reward variability. Such behavioral adaptation may be facilitated by neurons coding prediction errors relative to the standard deviation (SD) of reward distributions. To investigate this hypothesis, we required participants to predict the magnitude of upcoming reward drawn from distributions with different SDs. After each prediction, participants received a reward, yielding trial-by-trial prediction errors. In line with the notion of adaptive coding, BOLD response slopes in the Substantia Nigra/Ventral Tegmental Area (SN/VTA) and ventral striatum were steeper for prediction errors occurring in distributions with smaller SDs. SN/VTA adaptation was not instantaneous but developed across trials. Adaptive prediction error coding was paralleled by behavioral adaptation, as reflected by SD-dependent changes in learning rate. Crucially, increased SN/VTA and ventral striatal adaptation was related to improved task performance. These results suggest that adaptive coding facilitates behavioral adaptation and supports efficient learning.This study was supported by the Wellcome Trust (W.S., P.C.F.), Bernard Wolfe Health Neuroscience Fund (P.C.F.) and the Niels Stensen Foundation (K.M.J.D.). We thank William Stauffer, Armin Lak and Joost Haarsma for useful discussions.This is the final version of the article. It first appeared from Cell Press via http://dx.doi.org/10.1016/j.neuron.2016.04.01

Dopamine modulates the neural representation of subjective value of food in hungry subjects.

Although there is a rich literature on the role of dopamine in value learning, much less is known about its role in using established value estimations to shape decision-making. Here we investigated the effect of dopaminergic modulation on value-based decision-making for food items in fasted healthy human participants. The Becker-deGroot-Marschak auction, which assesses subjective value, was examined in conjunction with pharmacological fMRI using a dopaminergic agonist and an antagonist. We found that dopamine enhanced the neural response to value in the inferior parietal gyrus/intraparietal sulcus, and that this effect predominated toward the end of the valuation process when an action was needed to record the value. Our results suggest that dopamine is involved in acting upon the decision, providing additional insight to the mechanisms underlying impaired decision-making in healthy individuals and clinical populations with reduced dopamine levels.This is the author's accepted manuscript. The final version is available from the Society for Neuroscience in the Journal of Neuroscience at http://www.jneurosci.org/content/34/50/16856.abstract

Close-coupling calculations of low-energy inelastic and elastic processes in 4^4He collisions with H2_2: A comparative study of two potential energy surfaces

The two most recently published potential energy surfaces (PESs) for the HeH$_2$ complex, the so-called MR (Muchnick and Russek) and BMP (Boothroyd, Martin, and Peterson) surfaces, are quantitatively evaluated and compared through the investigation of atom-diatom collision processes. The BMP surface is expected to be an improvement, approaching chemical accuracy, over all conformations of the PES compared to that of the MR surface. We found significant differences in inelastic rovibrational cross sections computed on the two surfaces for processes dominated by large changes in target rotational angular momentum. In particular, the H$_2$($\nu=1, j=0$) total quenching cross section computed using the BMP potential was found to be a factor of $~$1000 larger than that obtained with the MR surface.Comment: 26 pages, 11 figure

Generalized field propagator for arbitrary finite-size photonic band gap structures

We investigate the properties of photonic band gap structures of finite size and arbitrary geometry using the density of states deduced from scattering calculations. We first demonstrate this procedure on a finite 2D array of cylinders and then study at optical frequencies a system formed by a finite array of finite height cylinders positioned on a substrate and illuminated with an evanescent field

HIFI spectroscopy of low-level water transitions in M82

We present observations of the rotational ortho-water ground transition, the two lowest para-water transitions, and the ground transition of ionised ortho-water in the archetypal starburst galaxy M82, performed with the HIFI instrument on the Herschel Space Observatory. These observations are the first detections of the para-H2O(111-000) (1113\,GHz) and ortho-H2O+(111-000) (1115\,GHz) lines in an extragalactic source. All three water lines show different spectral line profiles, underlining the need for high spectral resolution in interpreting line formation processes. Using the line shape of the para-H2O(111-000) and ortho-H2O+(111-000) absorption profile in conjunction with high spatial resolution CO observations, we show that the (ionised) water absorption arises from a ~2000 pc^2 region within the HIFI beam located about ~50 pc east of the dynamical centre of the galaxy. This region does not coincide with any of the known line emission peaks that have been identified in other molecular tracers, with the exception of HCO. Our data suggest that water and ionised water within this region have high (up to 75%) area-covering factors of the underlying continuum. This indicates that water is not associated with small, dense cores within the ISM of M82 but arises from a more widespread diffuse gas component.Comment: 5 pages, 4 figures. Accepted for publication in A&