Half-space theorems for minimal surfaces in Nil_3 and Sol_3

We prove some half-space theorems for minimal surfaces in the Heisenberg group Nil_3 and the Lie group Sol_3 endowed with their left-invariant Riemannian metrics. If S is a properly immersed minimal surface in Nil_3 that lies on one side of some entire minimal graph G, then S is the image of G by a vertical translation. If S is a properly immersed minimal surface in Sol_3 that lies on one side of a special plane, then S is another special plane.Comment: 19 pages, 3 figure

Half-space theorems and the embedded Calabi-Yau problem in Lie groups

We study the embedded Calabi-Yau problem for complete embedded constant mean curvature surfaces of finite topology or of positive injectivity radius in a simply-connected three-dimensional Lie group X endowed with a left-invariant Riemannian metric. We first prove a half-space theorem for constant mean curvature surfaces. This half-space theorem applies to certain properly immersed constant mean curvature surfaces of X contained in the complements of normal R^2 subgroups F of X. In the case X is a unimodular Lie group, our results imply that every minimal surface in X-F that is properly immersed in X is a left translate of F and that every complete embedded minimal surface of finite topology or of positive injectivity radius in X-F is also a left translate of F.Comment: 17 page

Allosteric activation of the nitric oxide receptor soluble guanylate cyclase mapped by cryo-electron microscopy.

Soluble guanylate cyclase (sGC) is the primary receptor for nitric oxide (NO) in mammalian nitric oxide signaling. We determined structures of full-length Manduca sexta sGC in both inactive and active states using cryo-electron microscopy. NO and the sGC-specific stimulator YC-1 induce a 71° rotation of the heme-binding β H-NOX and PAS domains. Repositioning of the β H-NOX domain leads to a straightening of the coiled-coil domains, which, in turn, use the motion to move the catalytic domains into an active conformation. YC-1 binds directly between the β H-NOX domain and the two CC domains. The structural elongation of the particle observed in cryo-EM was corroborated in solution using small angle X-ray scattering (SAXS). These structures delineate the endpoints of the allosteric transition responsible for the major cyclic GMP-dependent physiological effects of NO

Association of Sex, Fledging Date, and Sibling Relationships with Post-Fledging Movements of Burrowing Owls in a Nonmigratory Population in the Imperial Valley, California

Natal dispersal is an important driver of population and colonization dynamics, yet factors that affect timing and distance of post-fledging movements are poorly understood. We studied post-fledging movements of 34 (12 male and 22 female) juvenile Burrowing Owls (Athene cunicularia) between June 2002 and April 2003, in a nonmigratory population in the Imperial Valley, California. We found high variation in movement patterns among individuals. Juvenile Burrowing Owls left their nest throughout the year, with two females (6%) remaining within 100 m of their natal burrow until the beginning of the following year’s breeding season. Juvenile Burrowing Owls moved up to 11.7 km (males: 397 ± 124 m; females 1762 ± 630 m) between emergence from the nest to the following breeding season. Those that fledged early in the season remained closer to their nests for a longer period than those that fledged later in the season. Female Burrowing Owls remained ≤ 100 m from their natal nests for a longer duration than males. Members of male–female, but not male–male, sibling pairs were more likely to be within 100 m of one another than members of female–female sibling pairs. After members of sibling pairs were > 100 m apart, distance between members of sibling pairs was related only to time since fledging. Our study, conducted in a highly simplified agricultural environment, provides evidence that sex, fledging date, and sibling relationships can be responsible for the high individual variation in post-fledging movements of Burrowing Owls that has often been attributed to environmental variation.Keywords: Post-fledging movements, Athene cunicularia, Burrowing Owl, California, Sibling behavior, Natal dispersal, Imperial Valle

Parabolic stable surfaces with constant mean curvature

We prove that if u is a bounded smooth function in the kernel of a nonnegative Schrodinger operator $-L=-(\Delta +q)$ on a parabolic Riemannian manifold M, then u is either identically zero or it has no zeros on M, and the linear space of such functions is 1-dimensional. We obtain consequences for orientable, complete stable surfaces with constant mean curvature $H\in\mathbb{R}$ in homogeneous spaces $\mathbb{E}(\kappa,\tau)$ with four dimensional isometry group. For instance, if M is an orientable, parabolic, complete immersed surface with constant mean curvature H in $\mathbb{H}^2\times\mathbb{R}$, then $|H|\leq 1/2$ and if equality holds, then M is either an entire graph or a vertical horocylinder.Comment: 15 pages, 1 figure. Minor changes have been incorporated (exchange finite capacity by parabolicity, and simplify the proof of Theorem 1)

Seasonal Movements and Distribution of Steller’s Eiders (Polysticta stelleri) Wintering at Kodiak Island, Alaska

We used satellite telemetry in 2004–06 to describe the annual movements and habitat use of a segment of the Pacific population of Steller’s Eiders (Polysticta stelleri) that winters at Kodiak Island, Alaska. Information about broad-scale patterns of seasonal distribution and links among annual cycle stages is critical for interpreting population trends and developing conservation strategies. We captured birds in Chiniak Bay at Kodiak Island in late February and early March and monitored the movements after departure from Kodiak Island of 24 satellite-tagged birds: 16 after-second-year (ASY) age class females, one second-year age class female, and seven ASY males. All birds used the same intercontinental migration corridor during spring, but routes and chronology of spring migration appeared to vary by year and among individuals. Sixteen of the 24 birds that were tracked migrated to breeding areas along the Arctic coast of Russia from the Chukotka Peninsula to the Taymyr Peninsula; five birds, assumed to be non-breeding, spent the summer in nearshore waters of Russia and Alaska; and the remaining three birds either died during spring migration or had failed transmitters. Thirteen birds were tracked to molt sites that were broadly distributed along the coast of Alaska. Molt sites included St. Lawrence Island, the Kuskokwim Shoals, Kamishak Bay, and three sites along the Alaska Peninsula. Twelve of these 13 birds returned to Kodiak Island to winter, and a single male wintered on the Alaska Peninsula. Steller’s Eiders marked during winter at Kodiak Island were widely distributed during the breeding season, but a large proportion of marked birds returned to molting and wintering areas in two years of the study.De 2004 à 2006, nous avons recouru à la télémétrie satellitaire pour décrire l’utilisation de l’habitat et les mouvements annuels d’un segment de la population d’eiders de Steller (Polysticta stelleri) dans la région du Pacifique, eiders qui hivernent sur l’île Kodiak, en Alaska. Il est essentiel d’obtenir des données sur les tendances à grande échelle de la répartition saisonnière et des liens entre les divers stades du cycle annuel de ces oiseaux afin d’être en mesure d’interpréter leurs tendances démographiques et d’élaborer des stratégies de conservation. Nous avons capturé des oiseaux dans la baie Chiniak de l’île Kodiak vers la fin février et le début mars. Après notre départ de l’île Kodiak, nous avons surveillé les mouvements de 24 oiseaux pistés par satellite : 16 femelles de plus de deux ans, une femelle de deux ans et sept mâles de plus de deux ans. Tous les oiseaux ont emprunté le même couloir de migration intercontinental au printemps, mais les routes et la chronologie de la migration printanière semblaient varier d’une année à l’autre et d’un individu à l’autre. Seize des24 oiseaux pistés ont migré vers des aires de reproduction situées le long de la côte arctique de la Russie, depuis la presqu’île de Tchoukotkae jusqu’à la presqu’île de Taïmyr; cinq oiseaux, probablement non reproducteurs, ont passé l’été dans les eaux côtières de la Russie et de l’Alaska, tandis que les trois autres oiseaux sont morts pendant la migration printanière ou étaient dotés de transmetteurs défectueux. Treize oiseaux ont été repérés à des sites de mue largement répartis le long de la côte de l’Alaska. Parmi ces sites, notons ceux de l’île Saint-Laurent, du haut-fond de Kuskokwim, de la baie de Kamishak et de trois autres sites le long de la péninsule de l’Alaska. Douze de ces 13 oiseaux sont retournés à l’île Kodiak pour passer l’hiver, et un seul mâle a hiverné dans la péninsule de l’Alaska. Les eiders de Steller qui ont été marqués à l’île Kodiak pendant l’hiver étaient largement répartis pendant la saison de reproduction, mais une grande proportion d’oiseaux pistés sont retournés aux aires de mue et d’hivernage au cours des deux années visées par l’étude

High-resolution computed tomography reconstructions of invertebrate burrow systems

The architecture of biogenic structures can be highly influential in determining species contributions to major soil and sediment processes, but detailed 3-D characterisations are rare and descriptors of form and complexity are lacking. Here we provide replicate high-resolution micro-focus computed tomography (μ-CT) data for the complete burrow systems of three co-occurring, but functionally contrasting, sediment-dwelling inter-tidal invertebrates assembled alone, and in combination, in representative model aquaria. These data (≤2,000 raw image slices aquarium−1, isotropic voxel resolution, 81 μm) provide reference models that can be used for the development of novel structural analysis routines that will be of value within the fields of ecology, pedology, geomorphology, palaeobiology, ichnology and mechanical engineering. We also envisage opportunity for those investigating transport networks, vascular systems, plant rooting systems, neuron connectivity patterns, or those developing image analysis or statistics related to pattern or shape recognition. The dataset will allow investigators to develop or test novel methodology and ideas without the need to generate a complete three-dimensional computation of exemplar architecture

Parental bonding and identity style as correlates of self-esteem among adult adoptees and nonadoptees

Adult adoptees (n equals 100) and non-adoptees (n equals 100) were compared with regard to selfesteem, identity processing style, and parental bonding. While some differences were found with regard to self-esteem, maternal care, and maternal overprotection, these differences were qualified by reunion status such that only reunited adoptees differed significantly from nonadoptees. Moreover, hierarchical regression analyses indicated that parental bonding and identity processing style were more important than adoptive status per se in predicting self esteem. Implications for practitioners who work with adoptees are discussed

Activation of lactate receptor HCAR1 down-modulates neuronal activity in rodent and human brain tissue.

Lactate can be used by neurons as an energy substrate to support their activity. Evidence suggests that lactate also acts on a metabotropic receptor called HCAR1, first described in the adipose tissue. Whether HCAR1 also modulates neuronal circuits remains unclear. In this study, using qRT-PCR, we show that HCAR1 is present in the human brain of epileptic patients who underwent resective surgery. In brain slices from these patients, pharmacological HCAR1 activation using a non-metabolized agonist decreased the frequency of both spontaneous neuronal Ca <sup>2+</sup> spiking and excitatory post-synaptic currents (sEPSCs). In mouse brains, we found HCAR1 expression in different regions using a fluorescent reporter mouse line and in situ hybridization. In the dentate gyrus, HCAR1 is mainly present in mossy cells, key players in the hippocampal excitatory circuitry and known to be involved in temporal lobe epilepsy. By using whole-cell patch clamp recordings in mouse and rat slices, we found that HCAR1 activation causes a decrease in excitability, sEPSCs, and miniature EPSCs frequency of granule cells, the main output of mossy cells. Overall, we propose that lactate can be considered a neuromodulator decreasing synaptic activity in human and rodent brains, which makes HCAR1 an attractive target for the treatment of epilepsy

Anomalous Workfunction Anisotropy in Ternary Acetylides

Anomalous anisotropy of workfunction values in ternary alkali metal transition metal acetylides is reported. Workfunction values of some characteristic surfaces in these emerging semiconducting materials may differ by more than $\approx$ 2 eV as predicted by Density Functional Theory calculations. This large anisotropy is a consequence of the relative orientation of rod-like [MC$_{2}$]$_{\infty}$ negatively charged polymeric subunits and the surfaces, with M being a transition metal or metalloid element and C$_{2}$ refers to the acetylide ion C$_{2}^{2-}$, with the rods embedded into an alkali cation matrix. It is shown that the conversion of the seasoned Cs$_{2}$Te photo-emissive material to ternary acetylide Cs$_{2}$TeC$_{2}$ results in substantial reduction of its $\approx$ 3 eV workfunction down to 1.71-2.44 eV on the Cs$_{2}$TeC$_{2}$(010) surface while its high quantum yield is preserved. Similar low workfunction values are predicted for other ternary acetylides as well, allowing for a broad range of applications from improved electron- and light-sources to solar cells, field emission displays, detectors and scanners.Comment: Accepted for publication in Phys. Rev.