Topical Menthol Application Augments Cutaneous Microvascular Blood Flow

Please refer to the pdf version of the abstract located adjacent to the title

Effect of vasopressin 1b receptor blockade on the hypothalamic-pituitary-adrenal response of chronically stressed rats to a heterotypic stressor

Exposure to chronic restraint (CR) modifies the hypothalamic–pituitary–adrenal (HPA) axis response to subsequent acute stressors with adaptation of the response to a homotypic and sensitization of the response to a heterotypic stressor. Since vasopressin (AVP) activity has been reported to change during chronic stress, we investigated whether this was an important factor in HPA facilitation. We therefore tested whether vasopressin 1b receptor (AVPR1B) blockade altered the ACTH and corticosterone response to heterotypic stressors following CR stress. Adult male rats were exposed to CR, single restraint, or were left undisturbed in the home cage. Twenty-four hours after the last restraint, rats were injected with either a AVPR1B antagonist (Org, 30 mg/kg, s.c.) or vehicle (5% mulgofen in saline, 0.2/kg, s.c.) and then exposed to either restraint, lipopolysaccharide (LPS) or white noise. CR resulted in the adaptation of the ACTH and corticosterone response to restraint and this effect was not prevented by pretreatment with Org. Although we found no effect of CR on LPS-induced ACTH and corticosterone secretion, both repeated and single episodes of restraint induced the sensitization of the ACTH, but not corticosterone response to acute noise. Pretreatment with Org reduced the exaggerated ACTH response to noise after both single and repeated exposure to restraint

Ultranarrow conducting channels defined in GaAs-AlGaAs by low-energy ion damage

We have laterally patterned the narrowest conducting wires of two-dimensional electron gas (2DEG) material reported to date. The depletion induced by low-energy ion etching of GaAs-AlGaAs 2DEG structures was used to define narrow conducting channels. We employed high voltage electron beam lithography to create a range of channel geometries with widths as small as 75 nm. Using ion beam assisted etching by Cl2 gas and Ar ions with energies as low as 150 eV, conducting channels were defined by etching only through the thin GaAs cap layer. This slight etching is sufficient to entirely deplete the underlying material without necessitating exposure of the sidewalls that results in long lateral depletion lengths. At 4.2 K, without illumination, our narrowest wires retain a carrier density and mobility at least as high as that of the bulk 2DEG and exhibit quantized Hall effects. Aharonov–Bohm oscillations are seen in rings defined by this controlled etch-damage patterning. This patterning technique holds promise for creating one-dimensional conducting wires of even smaller sizes

Dissipation in nanocrystalline-diamond nanomechanical resonators

We have measured the dissipation and frequency of nanocrystalline-diamond nanomechanical resonators with resonant frequencies between 13.7 MHz and 157.3 MHz, over a temperature range of 1.4–274 K. Using both magnetomotive network analysis and a time-domain ring-down technique, we have found the dissipation in this material to have a temperature dependence roughly following T^(0.2), with Q^(–1) ≈ 10^(–4) at low temperatures. The frequency dependence of a large dissipation feature at ~35–55 K is consistent with thermal activation over a 0.02 eV barrier with an attempt frequency of 10 GHz

Effect of the glucocorticoid receptor antagonist Org 34850 on fast and delayed feedback of corticosterone release

We investigated the effect of the glucocorticoid receptor (GR) antagonist Org 34850 on fast and delayed inhibition of corticosterone secretion in response to the synthetic glucocorticoid methylprednisolone (MPL). Male rats were implanted with a catheter in the right jugular vein, for blood sampling and MPL administration, and with an s.c. cannula for Org 34850 administration. All experiments were conducted at the diurnal hormonal peak in the late afternoon. Rats were connected to an automated sampling system and blood samples were collected every 5 or 10 min. Org 34850 (10 mg/kg, s.c.) or vehicle (5% mulgofen in saline) was injected at 1630 h; 30 min later, rats received an injection of MPL (500 μg/rat, i.v.) or saline (0.1 ml/rat). We found that an acute administration of MPL rapidly decreased the basal corticosterone secretion and this effect was not prevented by acute pretreatment with Org 34850. However, blockade of GR with Org 34850 prevented delayed inhibition of MPL on corticosterone secretion measured between 4 and 12 h after MPL administration. Our data suggest an involvement of GR in modulating delayed, but not fast, inhibition induced by MPL on basal corticosterone secretion

Low-density Lipoprotiens, Body Mass Index, and the Female Sex Are Predictors of Reduced Cutaenous Reactive Hyperemia In Human Skin

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Surface dissipation in nanoelectromechanical systems: Unified description with the standard tunneling model and effects of metallic electrodes

By modifying and extending recent ideas [C. Seoanez et al., Europhys. Lett. 78, 60002 (2007)], a theoretical framework to describe dissipation processes in the surfaces of vibrating micro- and nanoelectromechanical devices, thought to be the main source of friction at low temperatures, is presented. Quality factors as well as frequency shifts of flexural and torsional modes in doubly clamped beams and cantilevers are given, showing the scaling with dimensions, temperature, and other relevant parameters of these systems. Full agreement with experimental observations is not obtained, leading to a discussion of limitations and possible modifications of the scheme to reach a quantitative fitting to experiments. For nanoelectromechanical systems covered with metallic electrodes, the friction due to electrostatic interaction between the flowing electrons and static charges in the device and substrate is also studied.Comment: 17 pages, 7 figure

Frequency of Killer Whale (Orcinus Orca) Attacks and Ship Collisions Based on Scarring on Bowhead Whales (Balaena Mysticetus) of the Bering-Chukchi-Beaufort Seas Stock

Bowhead whales of the Bering-Chukchi-Beaufort Seas stock harvested by Alaskan Eskimos were examined for scars from killer whale and ship-collision injuries. We estimated that the frequency of scars from killer whale attacks ranged from 4.1% to 7.9% (depending on our confidence that the whale was properly examined) while about 1% exhibited scars from ship collisions. The frequency of killer whale scars was considerably lower than for bowhead whales of the Davis Strait stock and for other baleen whales where data are available, and was significantly lower (P<0.05) for whales <13 m. Patterns of both types of scars were quite similar to those reported for other cretacean species. Spaces between rake marks were within the range of interdental measurements from four killer whale skulls. The occurrence of attempted killer whale predation and ship strikes inferred from scars has not prevented the BCBS stock from increasing.Key words: bowhead whale, killer whale, Alaskan Eskimos, whaling, scarring, ship/whale collision, propeller injuryOn a examiné des baleines boréales provenant du stock des mers de Béring, des Tchouktches et de Beaufort, prises par les Esquimaux de l'Alaska afin de voir si elles portaient des cicatrices résultant de morsures d'épaulards ou de blessures provoquées par des collisions avec des navires. On a estimé la gamme de fréquence des cicatrices venant d'attaques d'épaulards comme allant de 4,1 à 7,9 p. cent (compte tenu de notre niveau de certitude quant à la qualité de l'examen de la baleine), tandis qu'environ 1 p. cent des animaux montraient des cicatrices résultant de collisions avec des navires. La fréquence des cicatrices dues aux épaulards était bien inférieure à celle observée sur les baleines provenant du stock du détroit de Davis et d'autres cétacés à fanons pour lesquels on possédait des données. Les schémas des deux types de cicatrices étaient assez semblables à ceux rapportés pour d'autres espèces de cétacés. La fréquence des cicatrices dues aux épaulards était de beaucoup inférieure (P<0,05) pour les baleines mesurant moins de 13 m. Les espaces entre les éraflures se situaient dans la gamme d'écartement interdentaire mesuré sur le crâne de quatre épaulards. Les tentatives de prédation par les épaulards et les coups portés par les navires - déduits des cicatrices - n'ont pas empêché le stock des mers de Béring, des Tchouktches et de Beaufort d'augmenter.Mot clés: baleine boréale, épaulard, Esquimaux de l’Alaska, pêche à la baleine, cicatrices, collision navire/baleine, blessure infligée par une hélic

Strong coupling between single-electron tunneling and nano-mechanical motion

Nanoscale resonators that oscillate at high frequencies are useful in many measurement applications. We studied a high-quality mechanical resonator made from a suspended carbon nanotube driven into motion by applying a periodic radio frequency potential using a nearby antenna. Single-electron charge fluctuations created periodic modulations of the mechanical resonance frequency. A quality factor exceeding 10^5 allows the detection of a shift in resonance frequency caused by the addition of a single-electron charge on the nanotube. Additional evidence for the strong coupling of mechanical motion and electron tunneling is provided by an energy transfer to the electrons causing mechanical damping and unusual nonlinear behavior. We also discovered that a direct current through the nanotube spontaneously drives the mechanical resonator, exerting a force that is coherent with the high-frequency resonant mechanical motion.Comment: Main text 12 pages, 4 Figures, Supplement 13 pages, 6 Figure